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. 2023 Oct 18;8(43):40128–40139. doi: 10.1021/acsomega.3c02986

Biosorption Potential of Arachis hypogaea-Derived Biochar for Cd and Ni, as Evidenced through Kinetic, Isothermal, and Thermodynamics Modeling

Fozia Batool †,*, Rahman Qadir †, Fatima Adeeb †, Samia Kanwal †, Ehab A Abdelrahman ‡,§, Sobia Noreen †, Bedur Faleh A Albalawi ∥, Muhammad Mustaqeem †, Muhammad Imtiaz ⊥, Allah Ditta #,○,*, Humaira Yasmeen Gondal †
PMCID: PMC10620876  PMID: 37929083

Abstract

graphic file with name ao3c02986_0012.jpg

Biochar derived from plant biomass has great potential for the decontamination of aqueous media. It is the need of the hour to test biochar derived from economical, easily available, and novel materials. In this regard, the present study provides insight into the sorption of two heavy metals, i.e., cadmium (Cd) and nickel (Ni), using native Arachis hypogaea and its biochar prepared through pyrolysis. The effect of different factors, including interaction time, initial concentration of adsorbate, and temperature, as well as sorbent dosage, was studied on the sorption of Cd and Ni through a batch experiment. Characterization of the native biowaste and prepared biochar for its surface morphology and functional group identification was executed using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Results revealed the presence of different functional groups such as −OH on the surface of the adsorbent, which plays an important role in metal attachment. SEM reveals the irregular surface morphology of the adsorbent, which makes it easy for metal attachment. Thermogravimetric analysis shows the stability of A. hypogaea biochar up to 380 °C as compared with native adsorbent. The adsorption efficacy of A. hypogaea was found to be higher than that of native A. hypogaea for both metals. The best adsorption of Cd (94.5%) on biochar was observed at a concentration of 40 ppm, an adsorbent dosage of 2 g, a contact time of 100 min, and a temperature of 50 °C. While the optimum conditions for adsorption of Ni on biochar (97.2% adsorption) were reported at a contact time of 100 min, adsorbent dosage of 2.5 g, initial concentration of 60 ppm, and temperature of 50 °C. Results revealed that biochar offers better adsorption of metal ions as compared with raw samples at low concentrations. Isothermal studies show the adsorption mechanism as physical adsorption, and the negative value of Gibb’s free energy confirms the spontaneous nature of the adsorption reaction. An increase in entropy value favors the adsorption process. Results revealed that the sorbent was a decent alternative to eliminate metal ions from the solution instead of costly adsorbents.

Introduction

Since the beginning of the modern era, environmental pollution is posing adverse effects on the globe and has now turned into a major ecological problem.1,2 Several factors including global warming, depletion of the ozone layer, desertification, discharge of industrial effluents, and toxic compounds have increased the intensity of this issue.3 We are living in an era where tons of waste, especially industrial effluents, are produced every day and get dissolved in the drinking water and groundwater.4 These wastes carry heavy metals (HMs) that might be dangerous even in small quantities. Our soil, air, and water mediums are severely contaminated by HMs like magnesium (Mg), nickel (Ni), mercury (Hg), cadmium (Cd), chromium (Cr), lead (Pb), and arsenic (As) and therefore there is a dire need to protect the aquatic environment from such HMs due to their nonbiodegradable and toxic nature.5,6 HMs are persistently present in our environment, as they cannot be degraded by biological or any other organism.7 Their presence in water in an ionic form can affect aquatic life and sometimes endanger aquatic life.8

HMs, such as Cd and Ni, although present in low concentrations, adversely affect human beings and cause respiratory problems, immunological weakness, kidney and liver disorders, hypertension, genetic and neurological changes, cancer, and even lead to death.9−11 HMs have a toxic nature that links to protein-containing compounds and thus affects their efficiency as well as their structures.12,13 Several methodologies, such as precipitation, sorption, electrochemical techniques, filtration, sublimation, and floatation, have been employed and amended to eliminate the toxic HMs from wastewater.12,14−16 Among these methods, adsorption is the most economical and easy approach for the removal of unwanted metals from wastewater.17,18

One of the most critical points in the use of adsorbents is the suitability of their porous structures, adsorption velocity, and total adsorption capacity. A wide variety of solid materials can be used as organic carbon and adsorbents, but biochar (BC) is the most economical and cost-effective carbonaceous product.19−21 Major biomass materials used to prepare biochar are peanut shells, ryes, grass, rice husks, garlic stalk, straw, metropolitan solid waste, and wood waste products. An increase in the carbon content improves the biochar resistance to microbial decomposition. Presently, researchers are trying to investigate its usage as a soil conditioner.22 Favorable as well as encouraging use of this material in waste administration has been found. Nowadays, groundwater is continuously being deteriorated due to HMs and other pollutants. Recent studies have shown that biochar can adsorb harmful metals such as Cd, Hg, Cr, Pb, Zn, Cu, and Ni from wastewater.23,24

However, it is pertinent to observe the behavior of sorbent by correlating the sorbent equilibrium with selected parameters under specified conditions.25 Such correlations can be studied by employing the equilibrium isotherms that in turn sort out the monolayer/multilayer sorption processes based on the interaction between the sorbent and its surface.26−28 Similarly, the spontaneity of the adsorption process can be explained based on thermodynamic studies. Other factors, such as suitable temperature range and the nature of both sorbent and sorbate at equilibrium, can also be explained using these studies.29,30

In the present study, the adsorptive removal of Cd and Ni from the aqueous medium was tested using the raw biomass of Arachis hypogaea peels and its biochar. To our knowledge, no study has been conducted that involved the use of the raw biomass of Arachis hypogaea peels and its biochar as adsorbents. The synthesis of biochar was carried out from locally available waste biomass, i.e., peels of Arachis hypogaea (commonly known as peanut). The waste biomass could be easily obtained from house dustbins and from factories that use peanuts in their products such as biscuits and bakeries. The prepared biochar was further employed in the adsorption of Cd and Ni from the aquatic medium under selected parameters such as pH, initial concentration of sorbate, contact time, and concentration of sorbent. Moreover, isothermal, kinetic, and thermodynamic studies were conducted to observe the nature of the reaction.

Results and Discussion

The adsorption potential of biochar synthesized from synthetic A. hypogaea and native A. hypogaea was used to eliminate Cd and Ni from the aqueous solution.

Characterization of Sorbent

Characterization of the sorbent is a crucial factor of measurement. Surface morphology and functional groups present in the sorbent can be characterized by employing scanning electron microscopy and Fourier transform infrared spectroscopy, respectively.

Fourier Transform Infrared (FTIR) Spectroscopy

Results obtained from FTIR analysis of AH and AHB before and after the adsorption of Cd and Ni are listed in Figure 1. The hydroxyl group peak appears in the range of 3501–3009 cm–1, while the hydroxyl group (O–H) adsorption band appears at 3346 cm–1 and also on 3319.49 cm–1 before the sorption for biochar as well as native A. hypogaea. Inter- and intramolecular hydrogen bonding is accountable for stretching along with the broadening of the band of −OH in the FTIR spectrum. For the C–H bond, the range was 2920–2900 cm–1. A peak observed at 2341.58 cm–1 might be linked with C=N. Peaks in the range of 2001–1550 cm–1 are due to the C=C stretching vibrations in both adsorbents. For adsorption purposes, a significant role is played by the −OH group and heteroatoms to attach sorbate on the surface.31,32

Figure 1.

Figure 1

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FTIR spectra of native A. hypogaea and A. hypogaea biochar before and after adsorptionA clear shift in the band position of – OH is observed before and after the adsorption of metal ions from 3319 to 3325 and 3373 cm–1 for Ni and Cd ions attachment on native A. hypogaea, respectively. Similarly, for biochar, the −OH peak was obtained at 3340 cm–1, which shifted to 3486 and 3317 after Ni and Cd attachment with the surface of the adsorbent. A similar trend is reported by other researchers.33,34

Scanning Electron Microscopy (SEM)

The surface morphology of A. hypogaea is determined by scanning electron microscopy. Images of SEM of biochar and native A. hypogaea are shown in Figure 2. It is indicated from the images that the surface of the sorbent is rough and irregular, which enhances the speed of HM adsorption on the sorbent surface.33,35

Figure 2.

Figure 2

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SEM image of A. hypogaea (a, b) Native A. hypogaea, (c) A. hypogaea Biochar.

Thermogravimetric Analysis

Thermogravimetric analysis was performed to analyze the thermal stability of native A. hypogaea and its biochar. Results given in Figure S1 show that a loss of 5.5% of the weight was observed for native A. hypogaea from room temperature up to 150 °C due to moisture content present in the native adsorbent. This kind of weight loss is not observed for biochar samples, as it is already treated at high temperatures and contains no moisture content. A significant weight change was observed from 250 to 320 °C due to the decomposition of major constituents of native A. hypogaea. These components are cellulose, hemicellulose, and lignin, which contribute a major part in the mass of A. hypogaea. Cellulose starts decomposing at 275 °C and hemicellulose above 150 °C, while lignin shows degradation at 250 to 500 °C.36,37 So change in weight represented by arrow 1 may be due to cellulose and hemicellulose, while arrow 2 shows weight loss due to lignin decomposition. In A. hypogaea biochar a major weight change was observed at 350 °C due to lignin loss. Research outputs are in good agreement with the reported data.38

Absorption Study and Optimization of Parameters

The absorption study was based on the batch absorption method, and the surface parameters such as initial concentration of sorbate, interaction time, and concentration of sorbent were optimized to verify the best adsorption conditions for the sorbent (Figures S2 and S3). The stirring speed of the orbital shaker was kept at 150 rpm to observe the adsorption of Cd and Ni on raw and biochar A. hypogaea.

Effect of pH

Adsorption of metal ions is highly dependent on the pH factor as surface charge and metal ion attachment on the surface are decided by this factor. To optimize the factor of pH for the removal of Cd and Ni ions on AH and AHB, the experiment was performed in the pH range 1–7, as shown in Figure S2. As metal ions start precipitation in the basic pH range, the adsorption experiment was not extended above pH range 7. Adsorption efficiency was found to be small at low pH, as the oxygen of the adsorbent surface is protonated by an acidic pH range. However, a positive trend in the adsorption rate was observed by increasing the pH of the adsorption solution, and maximum adsorption potential was achieved at pH 6 for both metal ions. The optimization of other parameters (concentration of sorbate, contact time, amount of adsorbent, and temperature) discussed below was conducted at pH 6.

Concentration of Sorbate

To estimate the effect of changes in the concentration of HMs, solutions of varying concentrations such as 20, 40, 60, 80, and 100 ppm were prepared by adding 1 g of sorbent and stirring at a speed of 150 rpm for biochar and native A. hypogaea. These solutions were placed in an orbital shaker for 90 min and filtered. Atomic absorption spectroscopy was further employed to analyze the adsorption of Cd and Ni.

It was observed that the amount of Ni adsorption was found gradually increased with an increase in Ni ion concentration, and the maximum amount of Ni was adsorbed at 80 ppm initial concentration for both biochar and native A. hypogaea. By increasing Ni ion concentration more ions are available to attach on the surface of the adsorbent, so a positive trend in adsorption was observed but further raise in concentration have no prominent effect on the rate of adsorption as the surface of the adsorbent is completely saturated by metal ions and no more spaces are available to attach metal ions.36,39 The removal of the Cd ion concentration increased because of the positive effect of both biochar and native A. hypogaea; however, adsorption on biochar was found higher for both metal ions. Biochar provides an increase in surface area and hence more active sites for the attachment of these metal ions (Figure S3). These findings are in line with Tong et al.40 and Tungala et al.41

Contact Time

Contact time has been found to increase the ratio of metal adsorption for both metal ions on biochar and native A. hypogaea. Contact time was varied from 20 to 100 min and metal attachment enhanced as contact time was increased. Adsorption was found to reach 94% at 100 min of contact time for Ni on biochar and 81% on native A. hypogaea. Similarly, the Cd adsorption rate was found to be promising (93.5%) for biochar and 82% for native A. hypogaea. Initially, a sharp increase in adsorption rate was observed when contact time was increased from 20 to 40 min, but then adsorption increased slowly as active sites are gradually occupied by metal ions and less number of spaces are available. A similar trend is observed for the adsorption of other metal ions in reported data.42

Amount of Adsorbent

The amount of adsorbent is also considered to have a promising effect on the adsorption of metal ions. The amount of adsorbent was varied from 0.5 to 2.5 g and the adsorption experiment was repeated with 150 rpm shaking speed and 80 min contact time. Initially, a sharp increase in adsorption rate was observed for all the metal ions, as the amount of adsorbent provides attachment points to these metal ions and adsorption potential was found significant.

Temperature

The adsorption process is greatly affected by the temperature of the adsorption media, as an increase in temperature mostly causes an upshift in the adsorption rate due to an increase in the random movement of the metal ions. A similar trend was shown by Cd and Ni in the present study, as the temperature was raised, adsorption was found to increase up to 40 °C. However, further increases in temperature to 50 °C have found no significant addition to the adsorption rate; even for Cd on native A. hypogaea, a decrease in adsorption was observed. Due to an increase in temperature, the entropy of the system increased and this random movement of agro-waste particles enhanced their adsorption efficiency. The results are in line with Wu et al.30

Isothermal Study

Adsorption isotherms are generally proposed to properly correlate the interaction between the sorbate concentration and its accumulation on the surface of the sorbent at a maintained temperature. In this regard, a particular design may be optimized to remove the effluents from the aqueous system and different adsorption systems such as Langmuir, Freundlich, Redlich–Peterson, Temkin, and Elovich can also be utilized.37,42,43

Freundlich Isotherm of Adsorption

Freundlich adsorption isotherm is based on the concept of multilayer adsorption on sorbent and is developed for the heterogeneous system. This is completely explained by the linearized formula.

graphic file with name ao3c02986_m001.jpg

where Cads (mol g–1) and Ce (mol g–1) be there for equilibrium concentrations of sorbate, whereas Cm (mmol g–1) depicts the multilayer adsorption and 1/n stands for the constant degree of concentration of adsorption.38,44Figure 3 presents the Freundlich isotherm for the adsorption of Ni and Cd on biochar A. hypogaea and native A. hypogaea, respectively.

Figure 3.

Figure 3

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Freundlich isotherm for the adsorption of Cd and Ni on A. hypogaea (AH) and A. hypogaea biochar (AHB).

Freundlich adsorption capacity (KF) indicates the feasibility of the system, if its value is ranging from 1 to 20, then the adsorption process is considered favorable, and here in the current work, KF was 8.5 and 15.7, for Cd and Ni adsorption on A. hypogaea Biochar, respectively. Similarly, other parameters such as adsorption intensity (n) at 1.9 and 2.85 and the values of R2 (0.685 and 0.72) for Cd and Ni, respectively, were found to be significant and might be linked to the fitness of the model applied.

Langmuir Adsorption Isotherm

In this model, the relationship of adsorption concentration is studied and is usually applied to monolayer adsorbents that have homogeneous and smooth surfaces. Each site is held by one molecule at a constant energy level of the adsorption system. However, practically it is not possible hence all particles have equal surfaces and there is no interaction of adsorbate with molecules.45,46

Adsorption of sorbate on saturated sorbent at specific homogeneous places is considered by the Langmuir isotherm. To calculate the Langmuir model, the distribution of metal ions between liquid and solid surfaces was calculated by the equation given below, which shows the relationship of linearity.

graphic file with name ao3c02986_m002.jpg

Here, Q stands for the adsorption capacity of the sorbent and b (L mol–1) for perpetual energy for sorption. This process is not temperature-dependent. Figure 4 shows the Langmuir isotherm for the adsorption of Ni and Cd on biochar and native biomass.

Figure 4.

Figure 4

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Langmuir adsorption isotherm of Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

The initial concentration of RL (a dimensionless value) offers the applicability of the model for a system and if it ranges between 0 and 1, the system is more suitable for the adsorption and the results given in Table 1 lie within this range. Furthermore, the value of R2 was also near 1, which authenticates the validity of the model used for the present work.

Table 1. Linear Parameters of Isothermal Models for the Sorption of Cd and Ni.

  adsorption parameters for Cd removal
 adsorption parameters for Ni removal
models raw A. hypogaea A. hypogaea biochar raw A. hypogaea A. hypogaea biochar
Freundlich        
KF (mg/g) 0.35 8.53 0.14 15.80
n 0.55 1.92 0.50 2.86
R2 0.85 0.68 0.90 0.72
Langmuir        
Qo (mg/g) 1.26 6.02 0.64 23.26
KL/b –30.42 356.67 –8.31 1057.08
RL –0.00033 2.80 × 10–05 –0.0012 9.46 × 10–06
R2 0.54 0.93 0.73 0.96
Dubinin–Radushkevich        
kad (mol2/kJ2) 9.59 × 10–06 1.15 × 10–06 1.40 × 10–05 3.22 × 10–07
qs (mg/g) 40.45 32.69 37.34 39.25
R2 0.84 0.52 0.82 0.96
Temkin        
Β (J/mol) 36 11.70 29 8.30
KT 0.24 1.37 0.17 7.94
R2 0.79 0.84 0.79 0.84
Elovich        
Qm (mg/g) –31.75 –1.79 –28.74 20
KE 0.22 0.22 –0.26 0.22
R2 0.74 0.83 0.92 0.41
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Dubinin–Radushkevich Isotherm

Dubinin–Radushkevich isotherm is based on the empirical model that is much more generalized than Langmuir due to the exclusion of a homogeneous surface and constant sorption potential (Figure 5).

Figure 5.

Figure 5

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Dubinin–Radushkevich isotherm for adsorption of Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

This isotherm generally deals with the adsorption of vapors on heterogeneous systems (solid/liquid), and the results are presented in Table 1. Here the slope of the plot gives the value kad, and the intercept is qs. The model offered good feasibility of the adsorption system with a high value of R2 (0.959) near 1. This isotherm has found very promising applications in determining the nature (physical and chemical) of adsorption. The relationship used to determine the Dubinin isotherm was

graphic file with name ao3c02986_m003.jpg

Temkin Isotherm

As the contact between the sorbent and sorbate weakens, the value of the model or isotherm also decreases by keeping the heat of the adsorption variable (Figure 6). To determine Temkin isotherm, the following relationship is used.

graphic file with name ao3c02986_m004.jpg

In this equation, “R” is the universal gas constant (8.314 J mol–1 K–1), T is the temperature (30 °C or 303 K), and ΔQ gives the value of heat transferred in J mol–1, while KT is constant in the Tempkin model.

Figure 6.

Figure 6

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Temkin adsorption isotherm for Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

The information on binding energy is given by the equilibrium constant of binding KT, as given in Table 1. The model expresses the exothermic nature of the adsorption reaction as the value of B is greater than zero because heat is released in the process.37,47,48

Elovich Isotherm

As per Elovich’s model, the mechanism of adsorption was based on the chemical reactions, which are responsible for adsorption (Figure 7). The following relationship was used for the Elovich isotherm model:

graphic file with name ao3c02986_m005.jpg

Figure 7.

Figure 7

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Elovich isotherm for adsorption of Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

The plot of ln qe/Ce versus qe gives an R2 value that is close to unity, whereas the value of KE (intercept) and Qm (slope of the plot) represent the initial adsorption rate and adsorption constant, respectively. Furthermore, the value of R2 was also close to unity, which authenticates the applicability of the model.

Thermodynamic Studies

Literature shows that temperature has a promising effect on the adsorption capacity of the adsorbent.38 Adsorption of both metal ions was measured at variable temperature ranges by employing native A. hypogaea and A. hypogaea biochar as given in Table 2. Temperature was found to have a positive impact on the adsorption rate; as the temperature increases, diffusion of particles becomes high and adsorption is increased.

Table 2. Thermodynamic Parameters for Adsorption of Cd and Ni.

  thermodynamic parameters measured based on experimental results
metals adsorbed temp (K) ΔG° (kJ mol–1) ΔH° (kJ mol–1) ΔS° (J mol–1 K–1) R2
Cd adsorption on raw AH 293 –3.099 36.074 111.91 0.92
303 –2.621
313 –0.751
323 –0.023
Cd adsorption on AH biochar 293 –3.307 25.614 92.12 0.94
303 –3.817
313 –5.134
323 –6.161
Ni adsorption on raw AH 293 –2.217 8.073 20.20 0.90
303 –1.877
313 –1.657
323 –1.629
Ni adsorption on AH biochar 293 –1.932 38.211 124.71 0.92
303 –0.375
313 –1.262
323 –1.668
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A plot of ln Kl vs 1/T was obtained for metal ions adsorption on both adsorbents, as given in Figure 8. The value of enthalpy (ΔHo) and entropy (ΔSo) was obtained from slope and intercept, respectively. Gibb’s free energy was calculated by employing the equation.

Figure 8.

Figure 8

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Thermodynamic plot for the adsorption of Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

A negative value of Gibb’s free energy reflects the spontaneous nature of the adsorption process and positive results for Entropy and Enthalpy show the endothermic nature of the reaction as well as an increase in randomness during the adsorption process.45

Kinetic Studies

The time required for the adsorption process to attain equilibrium is determined by kinetic studies. For this purpose, pseudo first order (PFO) and pseudo second order (PSO) kinetic models were applied to the results to determine the mechanism of adsorption (Figure 9). For PFO kinetics, contact time was plotted against ln(qe – qt), and for PSO kinetics contact time was plotted against t/qt.

Figure 9.

Figure 9

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Pseudo-first-order kinetic plot for the adsorption of Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

Results show that adsorption of Cd on native A. hypogaea follows PSO kinetics with a R2 value of 0.91, and for A. hypogaea biochar, better results were obtained with the PFO model, giving a R2 value of 0.929 (Figure 10). Similarly, for the adsorption of Ni on native and A. hypogaea biochar, PSO order kinetics fit better with R2 0.9 and 0.97, respectively. According to the PFO kinetic model, physisorption is the rate-limiting step in the adsorption mechanism, and the PSO model describes the adsorption capacity of the system. The results are in line with Kochar et al.49 and Ke et al.50

Figure 10.

Figure 10

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Pseudo-second-order kinetic plot for the adsorption of Cd and Ni on raw A. hypogaea (AH) and A. hypogaea biochar (AHB).

Adsorbent Reuse/Regeneration

Adsorbents used in the present work can be regenerated and reused for the removal of pollutants with a satisfactory removal percentage, as shown in Figure 11. A. hypogaea (AH) and A. hypogaea biochar (AHB) were regenerated by treating with 0.1 M HCl for 1 h. The adsorbent was thoroughly washed with HCl to remove adsorbed metal ions from the surface and again utilized for metal uptake. Adsorbents were found to be stable, and regenerated adsorbents perform satisfactory uptake of metal ions. Regeneration adds value to the adsorption mechanism in terms of reduction in cost and waste management.

Figure 11.

Figure 11

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Regeneration and reuse of adsorbents [A. hypogaea (AH) and A. hypogaea biochar (AHB)] for adsorption purposes.

Conclusions

The present work utilized a seed waste material for the decontamination of Cd and Ni from wastewater. A comparison of the metal removal efficiency of native A. hypogaea and its biochar was made to remove Cd and Ni from the aqueous media. The adsorption efficiency of native A. hypogaea was 82.5 and 84.8%, while that of A. hypogaea biochar was 94.5 and 97.2% for Cd and Ni, respectively. Isothermal and kinetic studies reveal that the adsorption system follows multilayer adsorption with a physisorption mechanism. Thermodynamic studies revealed the spontaneous nature of adsorption with an increase in the system entropy. This study adds a significant contribution in terms of plant waste material reuse for environmental decontamination.

Materials and Methods

Preparation of Biochar from A. hypogaea L

Arachis hypogaea (AH) seed cover was washed with deionized water to remove any surface impurities. After proper drying of AH, it was crushed into a powder, and then the powder was changed into biochar by the process of pyrolysis. For pyrolysis, it was kept in a furnace under an anaerobic environment at 450 °C for 1.5–2 h. This treatment changes it into a dark brown color biochar called A. hypogaea biochar (AHB), which is harmless and easy to use for sorption. Dried AH and AHB were ground and passed through a 100-mesh sieve to obtain uniform particle sizes (2 mm) of adsorbents. Fine particle size offers more surface area for adsorption. Prepared adsorbents were stored in airtight bags for further use. Two HMs, i.e., Ni and Cd were selected as sorbents to evaluate the adsorption potential of native A. hypogaea and A. hypogaea biochar.

Characteristics of Biochar Adsorbent

Functional group and surface analysis methods were applied to determine the characteristics of biochar. Functional group analysis was performed by Fourier transform infrared spectroscopy (FTIR; Model No: Shimadzu FTIR 8400S, Kyoto, Japan) by employing a diffused reflectance infrared technique (DRIFT). In this technique, the adsorbent was mixed with potassium bromide (KBr) to obtain a FTIR spectra. The surface morphology was analyzed by SEM (FEI Nova, Nano-SEM 450, Lausanne, Switzerland). In brief, the electron beam was skimmed through a raster-scan design, and the image was made through the positioning of the beam, which responded with a concentration of the recognized signal. The resolution of the SEM was approximately 1 nm. The thermal stability of native A. hypogaea and A. hypogaea biochar was determined to evaluate the effective use of adsorbent under different temperature conditions by employing a thermal analyzer (Model No: Mettler Toledo Star SW 9.01, Greifensee, Switzerland).

Adsorption Experiment

Sorption was performed by batch adsorption methods to estimate the effect of different factors such as the concentration of sorbate, the time needed for sorption, and the initial concentration of sorbent.49,50 For evaluation of adsorption parameters, the contact time (10–70 min), initial concentration (20–100 ppm), and amount of adsorbent (0.5–2.5 g) were varied, and the adsorbed amount of metals was studied at equilibrium conditions by an atomic absorption spectrophotometer (AAS 65000 Shimadzu).

Equilibrium Isotherms

Adsorption isotherms were designed to study the adsorption pathway as well as the equilibrium relationship of sorbent with sorbate.51 These isotherms assist in predicting the behavior of the sorbent and different parameters such as thermodynamic and kinetic investigations toward sorption systems.

Isothermal Studies

For thermodynamic studies, the adsorption experiment was carried out at different temperature conditions, and the calculated parameters included enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG).

Kinetic Parameters

To study the adsorption kinetics, a linear and nonlinear form of pseudo-first and pseudo-second order kinetics was applied to the adsorption data.52 Adsorption of both metals was obtained at variable time intervals, and kinetic parameters were calculated.

Acknowledgments

The authors highly acknowledge the Institute of Chemistry, University of Sargodha, Sargodha 40100, Pakistan for the provision of research facilities for the present research work.

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.3c02986.

  • Figures S1: Thermogravimetric analysis of A. hypogaea (AH) and A. hypogaea biochar (AHB); Figure S2: Effect of pH on adsorption of Cd and Ni on A. hypogaea biochar (AHB) and A. hypogaea (AH); Figure S3: Factors affecting the adsorption of A. hypogaea (AH) and A. hypogaea biochar (AHB) at pH = 6 (PDF)

Author Contributions

Conceptualization: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G.; Data curation: F.B.; Formal analysis: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G.; Funding acquisition: B.F.A.A. and A.D.; Investigation: A.A.; Methodology: F.B. and R.Q.; Project administration: F.B. and A.D.; Resources: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G.; Software: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G.; Supervision: R.Q.; Validation: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G.; Visualization: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G.; Writing–original draft: A.A.; Writing–review and editing: F.B., R.Q., F.A., S.K., E.A.A., S.N., B.F.A.A., M.M., M.I., A.D., and H.Y.G. All authors have read and agreed to the published version of the manuscript.

The authors declare no competing financial interest.

Supplementary Material

ao3c02986_si_001.pdf (266.8KB, pdf)

References

  1. Dunlap R. E.; Catton W. R. J. Struggling with human exemptionalism: the rise, decline, and revitalization for environmental sociology. Am. Sociol. 1994, 25, 5–30. 10.1007/BF02691936. [DOI] [Google Scholar]
  2. Liang X.; Su Y.; Wang X.; Liang C.; Tang C.; Wei J.; Liu K.; Ma J.; Yu F.; Li Y. Insights into the heavy metal adsorption and immobilization mechanisms of CaFe-layered double hydroxide corn straw biochar: Synthesis and application in a combined heavy metal-contaminated environment. Chemosphere 2023, 313, 137467. 10.1016/j.chemosphere.2022.137467. [DOI] [PubMed] [Google Scholar]
  3. Singh R. L.; Singh P. K.. Global environmental problems. In Principles and Applications of Environmental Biotechnology for a Sustainable Future; Springer: Singapore, 2017; pp 13–41. [Google Scholar]
  4. Thassitou P. K.; Arvanitoyannis I. S. Bioremediation: A novel approach to food waste management. Trends Food Sci. Technol. 2001, 12, 185–196. 10.1016/S0924-2244(01)00081-4. [DOI] [Google Scholar]
  5. Nagajyoti P.; Lee K.; Sreekanth T. Heavy metals, occurrence and toxicity for plants: A review. Environ. Chem. Lett. 2010, 8, 199–216. 10.1007/s10311-010-0297-8. [DOI] [Google Scholar]
  6. Shi M.; Xie Q.; Li Z. L.; Pan Y. F.; Yuan Z.; Lin L.; Xu X. R.; Li H. X. Adsorption of heavy metals on biodegradable and conventional microplastics in the Pearl River Estuary, China. Environ. Pollut. 2023, 322, 121158. 10.1016/j.envpol.2023.121158. [DOI] [PubMed] [Google Scholar]
  7. Pathy A.; Pokharel P.; Chen X.; Balasubramanian P.; Chang S. X. Activation methods increase biochar’s potential for heavy-metal adsorption and environmental remediation: A global meta-analysis. Sci. Total Environ. 2023, 865, 161252. 10.1016/j.scitotenv.2022.161252. [DOI] [PubMed] [Google Scholar]
  8. Jitar O.; Teodosiu C.; Oros A.; Plavan G.; Nicoara M. Bioaccumulation of heavy metals in marine organisms from the Romanian sector of the Black Sea. New Biotechnol. 2015, 32, 369–378. 10.1016/j.nbt.2014.11.004. [DOI] [PubMed] [Google Scholar]
  9. Jaishankar M.; Tseten T.; Anbalagan N.; Mathew B. B.; Beeregowda K. N. Toxicity, mechanism and health effects of some heavy metals. Interdiscip. Toxicol. 2014, 7, 60–72. 10.2478/intox-2014-0009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Briffa J.; Sinagra E.; Blundell R. Heavy metal pollution in the environment and their toxicological effects on humans. Heliyon 2020, 6 (9), e04691. 10.1016/j.heliyon.2020.e04691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Rehman A. U.; Nazir S.; Irshad R.; Tahir K.; ur Rehman K.; Islam R. U.; Wahab Z. Toxicity of heavy metals in plants and animals and their uptake by magnetic iron oxide nanoparticles. J. Mol. Liq. 2021, 321, 114455. 10.1016/j.molliq.2020.114455. [DOI] [Google Scholar]
  12. Velusamy S.; Roy A.; Sundaram S.; Kumar Mallick T. A Review on Heavy Metal Ions and Containing Dyes Removal Through Graphene Oxide-Based Adsorption Strategies for Textile Wastewater Treatment. Chem. Rec. 2021, 21, 1570. 10.1002/tcr.202000153. [DOI] [PubMed] [Google Scholar]
  13. Vardhan K. H.; Kumar P. S.; Panda R. C. A review on heavy metal pollution, toxicity, and remedial measures: Current trends and future perspectives. J. Mol. Liq. 2019, 290, 111197. 10.1016/j.molliq.2019.111197. [DOI] [Google Scholar]
  14. Jiménez S.; Micó M. M.; Arnaldos M.; Medina F.; Contreras S. State of the art of produced water treatment. Chemosphere 2018, 192, 186–208. 10.1016/j.chemosphere.2017.10.139. [DOI] [PubMed] [Google Scholar]
  15. Natarajan S.; Boricha A. B.; Bajaj H. C. Recovery of value-added products from cathode and anode material of spent lithium-ion batteries. Waste Manage. 2018, 77, 455–65. 10.1016/j.wasman.2018.04.032. [DOI] [PubMed] [Google Scholar]
  16. Igunnu E. T.Treatment of produced water by simultaneous removal of heavy metals and dissolved polycyclic aromatic hydrocarbons in a photoelectrochemical cell; University of Nottingham, 2014. [Google Scholar]
  17. Shukla A.; Zhang Y.-H.; Dubey P.; Margrave J. L.; Shukla S. S. The role of sawdust in the removal of unwanted materials from water. J. Hazard. Mater. 2002, 95, 137–152. 10.1016/S0304-3894(02)00089-4. [DOI] [PubMed] [Google Scholar]
  18. Katheresan V.; Kansedo J.; Lau S. Y. Efficiency of various recent wastewater dye removal methods: A review. J. Environ. Chem. Eng. 2018, 6, 4676–4697. 10.1016/j.jece.2018.06.060. [DOI] [Google Scholar]
  19. Li J.; Yu Y.; Chen X.; Yu S.; Cui M.; Wang S.; Song F. Effects of biochar on the phytotoxicity of polyvinyl chloride microplastics. Plant Physiol. Biochem. 2023, 195, 228–237. 10.1016/j.plaphy.2023.01.022. [DOI] [PubMed] [Google Scholar]
  20. Mamun S. A.; Saha S.; Ferdush J.; Tusher T. R.; Islam M. S. Organic amendments for crop production, phosphorus bioavailability, and heavy metal immobilization: a review. Crop Pasture Sci. 2022, 73, 896. 10.1071/CP21726. [DOI] [Google Scholar]
  21. Alghamdi A. G.; Alasmary Z. Efficient Remediation of Cadmium- and Lead-Contaminated Water by Using Fe-Modified Date Palm Waste Biochar-Based Adsorbents. Int. J. Environ. Res. Public Health 2023, 20, 802. 10.3390/ijerph20010802. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Yang X.; Ikehata K.; Lerner R.; Hu Y.; Josyula K.; Chang S. X.; Liu Y. Agricultural Wastes. Water Environ. Res. 2010, 82, 1396–1425. 10.2175/106143010X12756668801338. [DOI] [Google Scholar]
  23. Patra J. M.; Panda S. S.; Dhal N. K. Biochar as a low-cost adsorbent for heavy metal removal: A review. Int. J. Res. Biosci. 2017, 6 (1), 1–7. [Google Scholar]
  24. Shrestha R.; Ban S.; Devkota S.; Sharma S.; Joshi R.; Tiwari A. P.; Kim H. Y.; Joshi M. K. Technological trends in heavy metals removal from industrial wastewater: A review. J. Environ. Chem. Eng. 2021, 9, 105688. 10.1016/j.jece.2021.105688. [DOI] [Google Scholar]
  25. Shao F.; Xu J.; Chen F.; Liu D.; Zhao C.; Cheng X.; Zhang J. Insights into olation reaction-driven coagulation and adsorption: A pathway for exploiting the surface properties of biochar. Sci. Total Environ. 2023, 854, 158595. 10.1016/j.scitotenv.2022.158595. [DOI] [PubMed] [Google Scholar]
  26. Foo K. Y.; Hameed B. Insights into the modeling of adsorption isotherm systems. Chem. Eng. J. 2010, 156, 2–10. 10.1016/j.cej.2009.09.013. [DOI] [Google Scholar]
  27. Batool F.; Akbar J.; Iqbal S.; Noreen S.; Bukhari S. N. A. Study of Isothermal, Kinetic, and Thermodynamic Parameters for Adsorption of Cadmium: An Overview of Linear and Nonlinear Approach and Error Analysis. Bioinorg. Chem. Appl. 2018, 2018, 1–11. 10.1155/2018/3463724. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Awang N. A.; Wan Salleh W. N.; Aziz F.; Yusof N.; Ismail A. F. A Review on Preparation, Surface Enhancement and Adsorption Mechanism of Biochar-Supported Nano Zero-Valent Iron Adsorbent for Hazardous Heavy Metals. J. Chem. Technol. Biotechnol. 2023, 98, 22–44. 10.1002/jctb.7182. [DOI] [Google Scholar]
  29. Al-Ghouti M. A.; Da’ana D. A. Guidelines for the Use and Interpretation of Adsorption Isotherm Models: A Review. J. Hazard. Mater. 2020, 393, 122383. 10.1016/j.jhazmat.2020.122383. [DOI] [PubMed] [Google Scholar]
  30. Wu M.; Liu B.; Li J.; Su X.; Liu W.; Li X. Influence of pyrolysis temperature on sludge biochar: the ecological risk assessment of heavy metals and the adsorption of Cd (II). Environ. Sci. Pollut. Res. 2023, 30 (5), 12608–12617. 10.1007/s11356-022-22827-x. [DOI] [PubMed] [Google Scholar]
  31. Mrad R.; Chehab G. Mechanical and Microstructure Properties of Biochar-Based Mortar: An Internal Curing Agent for PCC. Sustainability 2019, 11, 2491. 10.3390/su11092491. [DOI] [Google Scholar]
  32. Akpomie K. G.; Dawodu F. A. Potential of low-cost bentonite for heavy metal abstraction from the binary component system. Beni-Suef Univ. J. Basic Appl. Sci. 2015, 4, 1–13. 10.1016/j.bjbas.2015.02.002. [DOI] [Google Scholar]
  33. Limousin G.; Gaudet J.-P.; Charlet L.; Szenknect S.; Barthès V.; Krimissa M. Sorption isotherms: A review on physical bases, modeling, and measurement. Appl. Geochem. 2007, 22, 249–275. 10.1016/j.apgeochem.2006.09.010. [DOI] [Google Scholar]
  34. Zhou Y.; Zou Z.; Wang M.; Wang Y.; Li J.; Qiu L.; Cheng Y.; Dai Z. Biochar and nano-ferric oxide synergistically alleviate cadmium toxicity of muskmelon. Environ. Sci. Pollut. Res. 2023, 30, 57945–57959. 10.1007/s11356-023-26369-8. [DOI] [PubMed] [Google Scholar]
  35. Ye H.; Yu K.; Li B.; Guo J. Study on adsorption properties and mechanism of sodium hydroxide-modified ball-milled biochar to dislodge lead(II) and MB from water. Biomass Conv. Bioref. 2023, 1–15. 10.1007/s13399-023-03740-w. [DOI] [Google Scholar]
  36. Basu S.; Shivhare U. S.; Mujumdar A. S. Models for sorption isotherms for foods: A review. Dry. Technol. 2006, 24, 917–930. 10.1080/07373930600775979. [DOI] [Google Scholar]
  37. Khaled A.; Nemr A. E.; El-Sikaily A.; Abdelwahab O. Removal of Direct N Blue-106 from artificial textile dye effluent using activated carbon from orange peel: Adsorption isotherm and kinetic studies. J. Hazard. Mater. 2009, 165, 100–110. 10.1016/j.jhazmat.2008.09.122. [DOI] [PubMed] [Google Scholar]
  38. Hu X.; Chen C.; Zhang D.; Xue Y. Kinetics, isotherm and chemical speciation analysis of Hg(II) adsorption over oxygen-containing MXene adsorbent. Chemosphere 2021, 278, 130206. 10.1016/j.chemosphere.2021.130206. [DOI] [PubMed] [Google Scholar]
  39. Bayuo J.; Rwiza M.; Mtei K. Response surface optimization and modeling in heavy metal removal from wastewater - A critical review. Environ. Monit. Assess. 2022, 194 (5), 351. 10.1007/s10661-022-09994-7. [DOI] [PubMed] [Google Scholar]
  40. Tong X.; Song Q.; Wang L.; Hong Z.; Dong Y.; Jiang J. Effects of biochars derived from four crop straws on a Cd-polluted cinnamon soil. Environ. Sci. Pollut. Res. 2023, 30 (9), 24764–24770. 10.1007/s11356-023-25440-8. [DOI] [PubMed] [Google Scholar]
  41. Tungala L. S.; Mekala S.; Pala S. L.; Biftu W. K.; Ravindhranath K. Stem powder and its active carbon of Arachis hypogaea plant for lead (II) removal: application to treat battery-based industrial effluents. Int. J. Phytoremediation 2023, 25 (5), 598–608. 10.1080/15226514.2022.2095975. [DOI] [PubMed] [Google Scholar]
  42. Lin H.; Yang D.; Zhang C.; Liu W.; Zhang L.; Dong Y. Selective removal behavior of lead and cadmium from calcium-rich solution by MgO loaded soybean straw biochars and mechanism analysis. Chemosphere 2023, 319, 138010. 10.1016/j.chemosphere.2023.138010. [DOI] [PubMed] [Google Scholar]
  43. Murtaza G.; Ahmed Z.; Dai D.-Q.; Iqbal R.; Bawazeer S.; Usman M.; Rizwan M.; Iqbal J.; Akram M. I.; Althubiani A. S.; Tariq A.; Ali I. A review of mechanism and adsorption capacities of biochar-based engineered composites for removing aquatic pollutants from contaminated water. Front. Environ. Sci. 2022, 10, 2155. 10.3389/fenvs.2022.1035865. [DOI] [Google Scholar]
  44. Pathirana C.; Ziyath A. M.; Egodawatta P.; Bandara N. J.; Jinadasa K. B. S. N.; Bandala E. R.; Wijesiri B.; Goonetilleke A. Biosorption of heavy metals: Transferability between batch and column studies. Chemosphere 2022, 294, 133659. 10.1016/j.chemosphere.2022.133659. [DOI] [PubMed] [Google Scholar]
  45. Argun M. E.; Dursun S.; Ozdemir C.; Karatas M. Heavy metal adsorption by modified oak sawdust: Thermodynamics and kinetics. J. Hazard. Mater. 2007, 141, 77–85. 10.1016/j.jhazmat.2006.06.095. [DOI] [PubMed] [Google Scholar]
  46. Manikandan S. K.; Pallavi P.; Shetty K.; Bhattacharjee D.; Giannakoudakis D. A.; Katsoyiannis I. A.; Nair V. Effective Usage of Biochar and Microorganisms for the Removal of Heavy Metal Ions and Pesticides. Molecules 2023, 28 (2), 719. 10.3390/molecules28020719. [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Li J.; Dong X.; Liu X.; Xu X.; Duan W.; Park J.; Gao L.; Lu Y. Comparative Study on the Adsorption Characteristics of Heavy Metal Ions by Activated Carbon and Selected Natural Adsorbents. Sustainability 2022, 14 (23), 15579. 10.3390/su142315579. [DOI] [Google Scholar]
  48. Li Y.; Yin H.; Cai Y.; Luo H.; Yan C.; Dang Z. Regulating the exposed crystal facets of α-Fe2O3 to promote Fe2O3-modified biochar performance in heavy metals adsorption. Chemosphere 2023, 311, 136976. 10.1016/j.chemosphere.2022.136976. [DOI] [PubMed] [Google Scholar]
  49. Ke Y.; Zhang F.; Zhang Z.; Hough R.; Fu Q.; Li Y. F.; Cui S. Effect of combined aging treatment on biochar adsorption and speciation distribution for Cd (II). Sci. Total Environ. 2023, 867, 161593. 10.1016/j.scitotenv.2023.161593. [DOI] [PubMed] [Google Scholar]
  50. Kochar C.; Taneja L.; Yadav P. K.; Tripathy S. S. RSM-CCD approach for optimization study on effective remediation of lead and cadmium from water using surface-modified water caltrop peel biochar. Biomass Conv. Bioref. 2023, 10.1007/s13399-023-04013-2. [DOI] [Google Scholar]
  51. Wang Q.; Wen J.; Yang L.; Cui H.; Zeng T.; Huang J. Exploration of the role of different iron species in the remediation of As and Cd co-contamination by sewage sludge biochar. Environ. Sci. Pollut. Res. 2023, 30, 39154–39168. 10.1007/s11356-022-24952-z. [DOI] [PubMed] [Google Scholar]
  52. Zhou P. F.; Adeel M.; Guo M. L.; Ge L.; Shakoor N.; Li M. S.; Li Y. B.; Wang G. Y.; Rui Y. K. Characterisation of biochar produced from two types of chestnut shells for use in remediation of cadmium- and lead-contaminated soil. Crop Pasture Sci. 2022, 74, 147. 10.1071/CP21297. [DOI] [Google Scholar]

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