Skip to main content
NCBI home page
ACS Omega logoLink to ACS Omega
. 2020 Sep 28;5(39):25326–25333. doi: 10.1021/acsomega.0c03657

Low-Cost Efficient Magnetic Adsorbent for Phosphorus Removal from Water

Liting Zhang †, Hongbing Dan ‡, Orphe T Bukasa †, Linlin Song †, Yin Liu †, Liang Wang §, Jianjun Li †,*
PMCID: PMC7542858  PMID: 33043212

Abstract

graphic file with name ao0c03657_0011.jpg

Adsorption using magnetic adsorbents makes the phosphorus removal from water simple and efficient. However, most of the reported magnetic adsorbents use chemically synthesized nanoparticles as magnetic cores, which are expensive and environmentally unfriendly. Replacing the nanomagnetic cores by cheap and green magnetic materials is essential for the wide application of this technique. In this paper, coal-fly-ash magnetic spheres (MSs) were processed to produce a cheap and eco-friendly magnetic core. A magnetic adsorbent, ZrO2 coated ball-milled MS (BMS@ZrO2), was prepared through a simple chemical precipitation method. Careful structural investigations indicate that a multipore structural amorphous ZrO2 layer has grown on the MS core. The specific surface area of BMS@ZrO2 is 48 times larger than that of the MS core. The highest phosphorus adsorption is tested as 16.47 mg g–1 at pH = 2. The BMS@ZrO2 adsorbent has a saturation magnetization as high as 33.56 emu g–1, enabling efficient magnetic separation. Zeta potential measurements and X-ray photoelectron spectroscopy analysis reveal that the phosphorus adsorption of BMS@ZrO2 is triggered by the electrostatic attraction and the ligand exchange mechanism. The BMS@ZrO2 adsorbent could be reused several times after proper chemical treatment.

1. Introduction

Excessive phosphorus content is one of the main causes of eutrophication, which leads to short- and long-term environmental problems in various confined water bodies.1,2 On the other hand, phosphorus is an important industrial raw material, so it is important to recycle the phosphorus resource. Removing phosphorus from water remains an urgent task for environmental protection and phosphorus recycling. Many technologies have been explored to remove phosphorus from water.3,4 Chemical precipitation and biological phosphorus removal are the two most common methods for phosphate removal. Application of the chemical precipitation method is hindered by high cost, low efficiency, sludge handling problems, and possible secondary pollution. Meanwhile, the biological phosphorus removal method requires a large operation area and complex processes. Furthermore, the removal efficiency for trace concentrations of phosphorus is low in both methods. In contrast, adsorption is an economical and efficient approach for phosphorus removal, particularly from low concentrations in water.5 In addition, the adsorbed phosphorus can be easily retrieved. As a result, the adsorption method has attracted significant interest in the past two decades. As the key factor in adsorption, various P adsorbents have been fabricated and studied, including aluminum-based compounds,6 iron-based compounds,7 calcium-based compounds,8 lanthanum-based compounds,9,10 layered double hydroxides or oxides,11 ion exchange resins,12 mesoporous silicates,13 surface-modified natural minerals,14 and industrial solid wastes.15 Recently, zirconium-based compounds, such as mesoporous ZrO2, have been reported as being capable of removing phosphate ions from wastewater.16 Considering its tremendous affinity to phosphate ions, excellent biocompatibility, and high chemical inertness toward acids and alkalis, ZrO2 could serve as an effective and green P adsorbent.17,18

The other prominent difficulty for adsorption technology is the low solid–liquid separation efficiency due to the tiny diameter and high suspendability of the adsorbents. To address this problem, the magnetic separation technique was introduced. Various magnetic adsorbents have been explored and used in P adsorption.19 Most of these magnetic adsorbents have been core–shell-structured, however, and used magnetic nanoparticles, e.g., nanomagnetite, as a core. Given that nanomagnetic cores need to be chemically synthesized, the application of these magnetic adsorbents has been limited by their high cost, agglomeration, and significant environmental impact. In addition, possible oxidation of the Fe2+ in nanosized magnetite requires a hypercritical preservation condition. Finding green and cheap magnetic cores is necessary for the wide application of magnetic adsorbents.

Coal fly ash (CFA) is a bulk industrial waste product with tremendous output and widespread distribution, especially in developing countries where coal acts as major energy source. Coal-fly-ash magnetic spheres (MSs) are one of the major components of CFA, with a percentage of 2–23 wt %, depending on the mining environment.20 MS has strong magnetism, so it can be separated easily from CFA by magnetic separation. Since MS is a recycled resource extracted from industrial waste, it is cheap, in ample supply, and eco-friendly.21,22 MS particles are mainly porous ceramic balls with typical diameters of 1–100 μm and average densities of 3.1–3.9 g cm–1.23 Considering all the above features, MS is regarded as one of the most promising candidates for magnetic adsorbent cores, although raw MS cannot be used directly since the original diameter of MS is too large for water-treatment application. MS also contains some nonmagnetic impurities, which reduce the magnetism. Therefore, careful processing is required before magnetic core application.

In this study, MS was processed by ball milling and multilevel magnetic separation to prepare ball-milled MS magnetic cores (BMS). Then, BMS@ZrO2 magnetic P adsorbent was fabricated by a simple chemical precipitation method. The obtained samples were characterized in terms of morphology, composition, structure, magnetism, and specific surface area. The P adsorption performance of BMS@ZrO2 under different operation conditions was carefully investigated. The adsorption mechanism is discussed in detail.

2. Results and Discussion

2.1. Characterizations of BMS@ZrO2

The diameters of the BMS particles decreased to less than 5 μm after ball milling, with a D50 of 1.41 μm, as indicated in the particle diameter distribution curve (Figure S1). The composition, morphology, magnetism, and surface properties also changed dramatically.24 The scanning electron microscopy (SEM) images (Figure 1a,c) show that the BMS particles have a relatively smooth surface. In contrast, the surface of BMS@ZrO2 is rough with bumps and pores on the surface, showing that the BMS core has been well covered by the grown complex. As shown in the energy-dispersive spectroscopy (EDS) spectra (Figure 1b), there are Fe, O, Al, Si, and Ca peaks in the BMS EDS spectrum, but the Cu peak is owing to the copper sample holder used in the SEM observations and the unmarked peak is from the sputtering platinum. The presence of the distinct zirconium peak in the BMS@ZrO2 EDS spectrum (Figure 1 d) suggests that the coating material is a zirconium compound. The element contents of the BMS and BMS@ZrO2 are listed in Table 1. The presence of ZrO2 was further proven by the X-ray diffraction (XRD) spectra (Figure 2a) and X-ray photoelectron spectroscopy (XPS) analysis.

Figure 1.

Figure 1

Open in a new tab

(a, b) SEM image and EDS spectrum of BMS. (c, d) SEM image and EDS spectrum of BMS@ZrO2.

Table 1. Partial Element Content in BMS and BMS@ZrO2.

samples O (%) Fe (%) Si (%) Al (%) Ca (%) Zr (%)
BMS 21.79 55.80 12.73 5.36 0.93  
BMS@ZrO2 23.36 30.91 6.20 2.51 0.44 23.31
Open in a new tab

Figure 2.

Figure 2

Open in a new tab

(a) XRD spectra and (b) room-temperature magnetic hysteresis loops of BMS, BMS@ZrO2 (I) (synthesis condition: Zr4+ concentration was 0.02 M), and BMS@ZrO2 (II) (synthesis condition: Zr4+ concentration was 0.05 M). The inset of (b) shows that BMS@ZrO2 could be magnetically separated from treated water by a commercial magnet.

As shown in Figure 2a, the XRD spectra of BMS@ZrO2 (I) and BMS@ZrO2 (II) retained all the BMS diffraction peaks, including for quartz, magnetite, magnesioferrite, hematite, maghemite, and other trace compositions, although most of the diffraction intensity decreased with the increasing thickness of the ZrO2 coating. This suggests that the BMS structure did not change during the chemical reaction. A new wide diffraction peak appeared at around 2θ = 30°, indicating the formation of amorphous ZrO2.25 Since the processing ruled out most of the nonmagnetic components in MS, the BMS has stronger magnetism.22,24 As shown in Figure 2b, the saturation magnetization of BMS was found to be 37.89 emu g–1. The saturation magnetizations of BMS@ZrO2 (I) and BMS@ZrO2 (II) decreased to 33.56 and 25.91 emu g–1, respectively, due to the coating of nonmagnetic ZrO2. Even so, the magnetism of BMS@ZrO2 is strong enough for effective magnetic separation. As shown in the inset of Figure 2b, the BMS@ZrO2 adsorbents could be separated by a permanent magnet placed 2 cm away.

N2 adsorption/desorption isotherm measurements were performed to characterize the Brunauer–Emmett–Teller (BET) specific surface areas (SBET) of BMS and BMS@ZrO2. As shown in Table 2 and Figure 3, the SBET of BMS@ZrO2 (146.57 m2 g–1) is more than 48 times larger than that of the BMS (3.15 m2 g–1), and the total pore volume increased from 0.01 cm3 g–1 in BMS to 0.11 cm3 g–1. BMS@ZrO2 exhibits typical IV isotherms with an obvious hysteresis loop, indicating the presence of abundant mesopores in BMS@ZrO2.26 Considering the SEM result and the layer structure of BMS@ZrO2, the porous structure is most likely to have appeared with the growth of ZrO2.27 The high specific surface area would promote P adsorption.28

Table 2. BET Surface Properties of BMS and BMS@ZrO2.

samples BET surface area (m2 g–1) total pore volume (cm3 g–1) average pore diameter (nm)
BMS 3.15 0.01 15.63
BMS@ZrO2 146.57 0.11 3.55
Open in a new tab

Figure 3.

Figure 3

Open in a new tab

Pore size distributions and N2 adsorption/desorption isotherms (inset) of BMS and BMS@ZrO2.

2.2. Phosphorus Adsorption

2.2.1. Equilibrium P Adsorption Capacity

BMS powder and prepared BMS@ZrO2 adsorbents were used to treat two types of P-containing water, with concentrations of 10 and 20 mg L–1. As presented in Figure 4a, the equilibrium adsorption capacity of BMS@ZrO2 (16.47 mg g–1) was much higher than that of the BMS (2.42 mg g–1). BMS@ZrO2 exhibited better affinity toward the phosphorus ions due to the ZrO2 coating and its higher specific surface area. This was in good agreement with the BET result. According to the adsorption curves, the detailed P adsorption could be divided into two stages. Stage I occurred in the first 15 min followed by the long Stage II. In Stage I, P adsorption was very fast. A 12.54 mg P g–1 adsorption was reached at the end of 15 min. In contrast, P adsorption in Stage II was much slower, and the adsorption rate decreased gradually with the adsorption time. The adsorption process extended to approximately 3 h until the saturation adsorption was reached. The P adsorption capacity of BMS@ZrO2 was slightly lower than that of some reported amorphous nano-ZrO2 but higher than that of other zirconium adsorbents, as summarized in Table 3. Most of these ZrO2 based adsorbents also worked best under acidic conditions as BMS@ZrO2. Some other magnetic adsorbents, e.g., NaLa(CO3)2/Fe3O4, have even higher P adsorption. However, the core–shell structural BMS@ZrO2 has a large BMS core. If considering that the mass ratio of magnetic core in the material is more than 60%, the specific adsorption performance of ZrO2 should be much higher. In addition to the adsorption performance, the BMS@ZrO2 sample has other advantages. First, its magnetic core comes from a ready-made material, CMS. As a result, the synthetic process is simple and of low cost and produces less chemical waste liquid and other pollutants. Second, the CMS is originated from industrial waste coal fly ash; thus, the consumption of CMS has positive environmental effects. Third, the diameter of BMS@ZrO2 is in micron size and has strong magnetism; thus, it has a higher magnetic separation efficiency and is easier to operate in practical applications. Considering the low cost and efficient magnetic separation, high dosage addition can be used in actual P adsorption application.

Figure 4.

Figure 4

Open in a new tab

(a) Time-dependent P adsorption. (b) Effects of pH value on P absorption capacity and zeta potential of BMS@ZrO2.

Table 3. Comparison of P Adsorption Capacities for Reported Metal Oxide Adsorbents.
adsorbents pH adsorption capacity (mg g–1) ref.
mesoporous ZrO2 6.70–6.90 29.71 (29)
amorphous nano-ZrO2 6.20 32.31 (30)
NaLa(CO3)2/Fe3O4 4–11 77.85 (31)
Zr-La-shaddock peels 3 23.50 (32)
calcium silicate hydrate 8.50 14.79 (33)
crosslinked-chitosan-Fe(III) 3 10.20 (34)
La-modified rice husk biochar 3–10 25.04 (35)
ACF-LaOH 2 15.30 (36)
La-zeolite 3–7 17.20 (37)
graphene/La(OH)3 4 13.70 (38)
Fe-Zr binary oxide 4 13.65 (39)
Zr-loaded fibers 2–6.95 1.26–1.73 (40)
Ca-zeolite 4–9 7.57 (41)
BMS@ZrO2 2–3 16.47 present study
Open in a new tab

The P adsorption capacities of BMS@ZrO2 at different pH values are shown in Figure 4b. It is found that the solution pH value has a significant effect on P adsorption.42 P adsorption was high under low pH conditions. The highest adsorption of 16.47 mg g–1 was obtained at pH = 2. P adsorption declined sharply with increasing pH for pH > 3. In an alkaline environment, P adsorption became very weak. At pH = 10, the absorption capacity was only 1.82 mg g–1.

2.2.2. Adsorption Mechanism

To study the P adsorption mechanism of BMS@ZrO2, pseudo-first-order and pseudo-second-order kinetic models were used to fit the time-dependent experimental data, and the Freundlich and Langmuir models were chosen to fit the P adsorption isotherm equilibrium. As discussed in Sections 1 and 2 in the Supporting Information and illustrated in Figures S2 and S3 and Tables S1 and S2, the adsorption isotherm and kinetic fittings were better described by the Langmuir and pseudo-second-order models, indicating that the nature of the P adsorption was monolayer chemical adsorption. It is well known that surface hydroxyl groups play an important role in the adsorption process.42 According to the FTIR investigation (Figure S4), there are a large number of hydroxyl and deformed hydroxyl groups on the surface of BMS@ZrO2. The properties of the surface hydroxyl groups changed with the chemical environment. When the solution pH was lower than the point of zero charge (PZC) of the material, the surface hydroxyl groups were protonated and positively charged. Otherwise, the surface hydroxyl groups were negatively charged. The zeta potential results for BMS@ZrO2 are presented in Figure 4b. It shows that the PZC of BMS@ZrO2 is at pH = 6.76 and that the highest zeta potential are observed when the solution pH = 2. The BMS@ZrO2 surface was positively charged at pH < 6.76 and negatively charged below pH > 6.76. In the P adsorption process, the pH value ranged from 2 to 10, where the dominant phosphate species were negatively charged H2PO4– and HPO42– anions.43 Therefore, the phosphate anions tended to be adsorbed on the BMS@ZrO2 surface by electrostatic attraction when pH < 6.76. The specific reaction processes are expressed by eqs 1–3. Under lower pH conditions, the zeta potential of BMS@ZrO2 was more positive, and thus the adsorption of phosphate anions was stronger.42 This was in good agreement with the P adsorption results.

2.2.2. 1
2.2.2. 2
2.2.2. 3

The surface properties of BMS@ZrO2 before and after P adsorption were characterized by XPS. As shown in Figure 5a, there is a new peak at approximately 133.84 eV in the XPS curve of the P-adsorbed BMS@ZrO2. This peak corresponds to the phosphate group, indicating the adsorption of phosphate anions on the BMS@ZrO2 surface.44 The Zr 3d spectra of BMS@ZrO2, before and after P adsorption, are shown in Figure 5b. An obvious binding energy change in the 3d electrons can be observed. The Zr 3d5/2 binding energies of the original and P adsorbed BMS@ZrO2 are 182.22 and 182.82 eV, respectively, while the corresponding Zr 3d3/2 binding energies are 184.44 and 185.28 eV, respectively. The increase in binding energy indicates the chemical bonding between the zirconium oxide and the phosphate groups.45 Since the P ion has a higher electronegativity than the H ion, the Zr ion loses electron density after P adsorption, leading to the increase in the Zr 3d5/2 and 3d3/2 binding energies. An obvious increase in the solution pH was observed with the P adsorption when pH < 8.9, as shown in Figure 6a. As discussed above, the P adsorption is dominated by the monolayer chemical adsorption and is closely related to the surface hydroxyl groups. Therefore, we could assume that the ligand exchange mechanism played an important role in the P adsorption of BMS@ZrO2.27,46 In this mechanism, an exchange between hydroxyl groups and phosphate ions occurred in the adsorption process, and the pH increased for the sustained release of OH– ions. The ligand exchange mechanism could be expressed as follows:

2.2.2. 4
2.2.2. 5
Figure 5.

Figure 5

Open in a new tab

(a) XPS patterns of BMS and BMS@ZrO2 before and after P adsorption. (b) Zr 3d binding energy of BMS@ZrO2 before and after P adsorption over a wide region.

Figure 6.

Figure 6

Open in a new tab

(a) Solution pH changes before and after P adsorption on BMS@ZrO2. (b) Comparison of the pH changes with the presence of BMS@ZrO2 between the P-containing solution and the solution without P.

Interestingly, the solution pH decreased slightly with the P adsorption under high-pH conditions. This pH decrease could be attributed to the deprotonation of the surface hydroxyl groups from the release of H+.47 According to the ligand exchange mechanism, OH– was released into the solution during the P adsorption process. Under strong alkaline conditions, however, the P adsorption was very slow, so the release of OH– became very weak. The OH– production was even slower than the H+ release. This finding was further proven by an adsorption experiment comparing the pH changes in the solutions containing P and without P, as shown in Figure 6b. Above all, a mechanism combining electrostatic attraction with ligand exchange is likely to dominate the P adsorption process of BMS@ZrO2. Electrostatic attraction and ligand exchange work simultaneously but depend on the solution pH. The whole P adsorption mechanism is presented in Figure 7. From the discussion above, it is found that the phosphorus adsorption of BMS@ZrO2 is a two-stage complex process and the adsorption mechanism is different from most of the previous reports.

Figure 7.

Figure 7

Open in a new tab

Schematic illustration of the BMS@ZrO2 P adsorption mechanism at different pH values.

2.2.3. Desorption of P and Reuse of BMS@ZrO2

Phosphate ions adsorbed on BMS@ZrO2 could be separated magnetically and desorbed in NaOH solution. The desorbed phosphorus had a relatively high concentration, and thus, it could be retrieved easily for recycling. The used BMS@ZrO2 could be reused as a P adsorbent after proper chemical treatment, as described in Section 3. The P adsorption of the recycled BMS@ZrO2 is demonstrated in Figure 8. The P adsorption capacity decreased slowly with increasing cycle time. After four cycles, the P adsorption remained at over 60% of the original adsorption capacity.

Figure 8.

Figure 8

Open in a new tab

P adsorption performance of the regenerated BMS@ZrO2.

3. Methods

3.1. Materials and Reagents

The CFA used in this study was obtained from Luohe power plant in Huainan, China. Zirconyl chloride (ZrOCl2·8H2O), anhydrous potassium dihydrogen orthophosphate (KH2PO4), ascorbic acid (C6H8O6), ammonium molybdate ((NH4)6Mo7O24·4H2O), antimony potassium tartrate (KSbC4H4O7·1/2H2O), concentrated hydrochloric acid (HCl, 32–38%), and sodium hydroxide (NaOH, 98%) were all purchased from Shanghai Nanoport Company (Shanghai, China). All the reagents were of analytical reagent grade.

The P-containing waste water was prepared by dissolving KH2PO4 in an appropriate amount of deionized water. The pH of the solution was adjusted by 0.1 M NaOH and/or HCl.

3.2. Preparation of BMS

The preparation of BMS particles included multilevel magnetic separation of CFA and the ball-milling treatment of MS.24 Briefly, crude MS was obtained by using a magnetic separation tube to process 100 mesh CFA under the strong magnetic field of 300 mT followed by weak magnetic separation (100 mT) to obtain the refined MS. The refined MS was ball-milled for 10 h at a rotation speed of 400 rpm followed by weak magnetic separation (100 mT) to obtain the BMS.

The BMS@ZrO2 magnetic adsorbent was synthesized via a chemical precipitation method. A certain amount of BMS particles was dispersed into 100 mL of 0.05 M ZrOCl2·8H2O solution and sonicated for 10 min. Then, 6 M NaOH solution was added dropwise until the pH value reached 8.5. A stirring rate of 400 rpm was maintained throughout the titration process. The suspension was stirred continuously for 6 h. Subsequently, the precipitates were collected by an external magnetic field and washed with deionized water and ethanol. Finally, the product was dried at 60 °C in a vacuum drier for 24 h and sealed for later P adsorption experiments. The synthesis of BMS@ZrO2 is schematically illustrated in Figure 9.

Figure 9.

Figure 9

Open in a new tab

Synthetic procedure for BMS@ZrO2.

3.3. Characterization and Measurements

The prepared adsorbents were characterized by various techniques as follows. The distribution of MS particle diameters before and after ball milling was measured by a SALD-7101 LDPAZ (Japan). The crystalline structure was characterized using a Bruker D8-Focus X-ray diffractometer by applying monochromated Cu Kα radiation (λ = 0.15418 nm) in the 2θ range of 20–80 ° at 2°·min–1. The morphology and elemental composition were analyzed by a JSM-7001F SEM (JEOL, Japan) equipped with and EDS (Oxford, Britain) operating at 20 kV. XPS (ESCALAB 250Xi, Thermo Fisher Scientific, USA) was used to measure the chemical composition and the binding energy of Zr 3d before and after P adsorption. A VSM (Lake Shore 7400, USA) was used to measure the room-temperature magnetism of the magnetic adsorbents. BET surface areas and pore size distributions were determined through N2 adsorption/desorption over a Micromeritics ASAP 2010 system (Micromeritics, USA) at 77 K. A ZetaProbe 7020 Zeta-Potential meter was used to analyze the zeta potential. A FTIR (Thermo Scientific Nicolet iS50, USA) was used to analyze functional groups on the adsorbents in the region of 4000–400 cm–1.

3.4. P Adsorption Experiment

All P adsorption experiments were performed at room temperature in 250 mL glass beakers. A 150 mL home-made phosphate solution was used in each experiment, with a fixed dose of BMS@ZrO2 at 0.5 g L–1. The mixture was stirred electrically at 200 rpm for a certain time. After the adsorption, 10 mL of supernatant solution was extracted, centrifuged, and subjected to residual phosphate concentration analysis. The concentration of phosphate was determined using ultraviolet–visible (UV–Vis) spectrometry. The phosphate adsorption capacity was calculated according to the following equation:

3.4. 6

where qe is the equilibrium adsorption capacity (mg g–1), C0 is the initial phosphate concentration (mg L–1), Ce is the equilibrium phosphate concentration (mg L–1), V is the volume of phosphate solution (L), and m is the mass of the adsorbent (g).

Two initial phosphate concentrations of 10 and 20 mg L–1 were used in the P adsorption experiments. The initial solution pH was adjusted from 2 to 10, and the adsorption time was 0–3 h. Pseudo-first-order and pseudo-second-order kinetic models were used to fit the time-dependent experimental data. The effect of the solution pH on P adsorption was studied using the 20 mg L–1 concentration phosphate solution. The adsorption time was 3 h. The effects of coexisting anions on phosphate adsorption were evaluated by adding NaNO3, Na2SO4, and Na2CO3 at concentrations of 0, 0.05, 0.1, 0.15, and 0.20 M; the initial solution pH was 2, and the adsorption time was 3 h. For the equilibrium adsorption isotherm study, the initial phosphate concentration ranged from 1 to 20 mg L–1, and the adsorption time was 3 h. The adsorption equilibrium was investigated through Freundlich and Langmuir model isotherm adsorption fitting.

P desorption experiments under alkaline conditions were performed in five consecutive cycles to test the reusability of BMS@ZrO2. In each cycle, the BMS@ZrO2 adsorbent after adsorption was treated in 0.2 M NaOH solution under mechanical stirring at 500 rpm for 12 h. The adsorbent was then separated magnetically and washed thoroughly with deionized water until neutral pH was achieved. The regenerated adsorbent was dried at 60 °C for 12 h in a vacuum drier. In the re-adsorption experiments, the initial phosphate concentration was 20 mg L–1, the pH was 2, and the adsorption time was 3 h.

Acknowledgments

This work was financially supported by the Natural Science Foundation of Anhui Province, China (grant no. 1908085ME127), National Natural Science Foundation of China (grant no. 51374015), and the Higher Education Natural Science Project of Anhui Province (grant no. KJ2016A189).

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.0c03657.

  • Adsorption kinetic model and fitting, adsorption isotherm model and fitting, FTIR investigation, partial element content in BMS and BMS@ZrO2, and particle diameter distributions of MS before and after ball milling (PDF)

The authors declare no competing financial interest.

Supplementary Material

ao0c03657_si_001.pdf (294.6KB, pdf)

References

  1. Diaz R. J.; Rosenberg R. Spreading dead zones and consequences for marine ecosystems. Science 2008, 321, 926–929. 10.1126/science.1156401. [DOI] [PubMed] [Google Scholar]
  2. Mayer B. K.; Baker L. A.; Boyer T. H.; Drechsel P.; Gifford M.; Hanjra M. A.; Parameswaran P.; Stoltzfus J.; Westerhoff P.; Rittmann B. E. Total Value of Phosphorus Recovery. Environ. Sci. Technol. 2016, 50, 6606. 10.1021/acs.est.6b01239. [DOI] [PubMed] [Google Scholar]
  3. Loganathan P.; Vigneswaran S.; Kandasamy J.; Bolan N. S. Removal and Recovery of Phosphate From Water Using Sorption. Crit. Rev. Environ. Sci. Technol. 2014, 44, 847–907. 10.1080/10643389.2012.741311. [DOI] [Google Scholar]
  4. Morse G. K.; Brett S. W.; Guy J. A.; Lester J. N. Review: Phosphorus removal and recovery technologies. Sci. Total Environ. 1998, 212, 69–81. 10.1016/S0048-9697(97)00332-X. [DOI] [Google Scholar]
  5. Zhang Y.; Huang S.; Guo D.; Zhang S.; Song X.; Yue K.; Zhang K.; Bao D. Phosphorus adsorption and desorption characteristics of different textural fluvo-aquic soils under long-term fertilization. J. Soils Sediments 2019, 19, 1306–1318. 10.1007/s11368-018-2122-0. [DOI] [Google Scholar]
  6. Yin Q.; Ren H.; Wang R.; Zhao Z. Evaluation of nitrate and phosphate adsorption on Al-modified biochar: Influence of Al content. Sci. Total Environ. 2018, 631-632, 895–903. 10.1016/j.scitotenv.2018.03.091. [DOI] [PubMed] [Google Scholar]
  7. Wilfert P.; Kumar P. S.; Korving L.; Witkamp G.-J.; van Loosdrecht M. C. M. The Relevance of Phosphorus and Iron Chemistry to the Recovery of Phosphorus from Wastewater: A Review. Environ. Sci. Technol. 2015, 49, 9400–9414. 10.1021/acs.est.5b00150. [DOI] [PubMed] [Google Scholar]
  8. Han C.; Lalley J.; Iyanna N.; Nadagouda M. N. Removal of phosphate using calcium and magnesium-modified iron-based adsorbents. Mater. Chem. Phys. 2017, 198, 115–124. 10.1016/j.matchemphys.2017.05.038. [DOI] [Google Scholar]
  9. Chen M.; Huo C.; Li Y.; Wang J. Selective Adsorption and Efficient Removal of Phosphate from Aqueous Medium with Graphene–Lanthanum Composite. ACS Sustainable Chem. Eng. 2015, 4, 1296–1302. 10.1021/acssuschemeng.5b01324. [DOI] [Google Scholar]
  10. Khan M.; Lo I. M. C. A holistic review of hydrogel applications in the adsorptive removal of aqueous pollutants: Recent progress, challenges, and perspectives. Water Res. 2016, 106, 259–271. 10.1016/j.watres.2016.10.008. [DOI] [PubMed] [Google Scholar]
  11. Lundehøj L.; Jensen H. C.; Wybrandt L.; Nielsen U. G.; Christensen M. L.; Quist-Jensen C. A. Layered double hydroxides for phosphorus recovery from acidified and non-acidified dewatered sludge. Water Res. 2019, 153, 208–216. 10.1016/j.watres.2019.01.004. [DOI] [PubMed] [Google Scholar]
  12. Gungor M. A.; Ozalp Ö.; Arar Ö. Removal of tripolyphospate from water by ion exchange resins. Desalin. Water Treat. 2017, 88, 279–285. 10.5004/dwt.2017.21450. [DOI] [Google Scholar]
  13. Choi J.-W.; Hong S.-W.; Kim D.-J.; Lee S.-H. Investigation of phosphate removal using sulphate-coated zeolite for ion exchange. Environ. Technol. 2012, 33, 2329–2335. 10.1080/09593330.2012.666569. [DOI] [PubMed] [Google Scholar]
  14. Krishnan K. A.; Haridas A. Removal of phosphate from aqueous solutions and sewage using natural and surface modified coir pith. J. Hazard. Mater. 2008, 152, 527–535. 10.1016/j.jhazmat.2007.07.015. [DOI] [PubMed] [Google Scholar]
  15. Chen J.; Kong H.; Wu D.; Chen X.; Zhang D.; Sun Z. Phosphate immobilization from aqueous solution by fly ashes in relation to their composition. J. Hazard. Mater. 2007, 139, 293–300. 10.1016/j.jhazmat.2006.06.034. [DOI] [PubMed] [Google Scholar]
  16. Liu T.; Feng J.; Wan Y.; Zheng S.; Yang L. ZrO2 nanoparticles confined in metal organic frameworks for highly effective adsorption of phosphate. Chemosphere 2018, 210, 907–916. 10.1016/j.chemosphere.2018.07.085. [DOI] [PubMed] [Google Scholar]
  17. Ju X.; Hou J.; Tang Y.; Sun Y.; Zheng S.; Xu Z. ZrO2 nanoparticles confined in CMK-3 as highly effective sorbent for phosphate adsorption. Microporous Mesoporous Mater. 2016, 230, 188–195. 10.1016/j.micromeso.2016.05.002. [DOI] [Google Scholar]
  18. Wang W.; Zhou J.; Wei D.; Wan H.; Zheng S.; Xu Z.; Zhu D. ZrO2-functionalized magnetic mesoporous SiO2 as effective phosphate adsorbent. J. Colloid Interface Sci. 2013, 407, 442–449. 10.1016/j.jcis.2013.06.053. [DOI] [PubMed] [Google Scholar]
  19. Lai L.; Xie Q.; Chi L.; Gu W.; Wu D. Adsorption of phosphate from water by easily separable Fe3O4@SiO2 core/shell magnetic nanoparticles functionalized with hydrous lanthanum oxide. J. Colloid Interface Sci. 2016, 465, 76–82. 10.1016/j.jcis.2015.11.043. [DOI] [PubMed] [Google Scholar]
  20. Blissett R. S.; Rowson N. A. A review of the multi-component utilisation of coal fly ash. Fuel 2012, 97, 1–23. 10.1016/j.fuel.2012.03.024. [DOI] [Google Scholar]
  21. Yao Z. T.; Ji X. S.; Sarker P. K.; Tang J. H.; Ge L. Q.; Xia M. S.; Xi Y. Q. A comprehensive review on the applications of coal fly ash. Earth-Sci. Rev. 2015, 141, 105–121. 10.1016/j.earscirev.2014.11.016. [DOI] [Google Scholar]
  22. Zyryanov V. V.; Petrov S. A.; Matvienko A. A. Characterization of spinel and magnetospheres of coal fly ashes collected in power plants in the former USSR. Fuel 2011, 90, 486–492. 10.1016/j.fuel.2010.10.006. [DOI] [Google Scholar]
  23. Bajukov O. A.; Anshits N. N.; Petrov M. I.; Balaev A. D.; Anshits A. G. Composition of ferrospinel phase and magnetic properties of microspheres and cenospheres from fly ashes. Mater. Chem. Phys. 2009, 114, 495–503. 10.1016/j.matchemphys.2008.09.061. [DOI] [Google Scholar]
  24. Li J.; Zhu J.; Qiao S.; Yu Z.; Wang X.; Liu Y.; Meng X. Processing of coal fly ash magnetic spheres for clay water flocculation. Int. J. Miner. Process. 2017, 169, 162–167. 10.1016/j.minpro.2017.11.006. [DOI] [Google Scholar]
  25. Chitrakar R.; Tezuka S.; Sonoda A.; Sakane K.; Ooi K.; Hirotsu T. Synthesis and phosphate uptake behavior of Zr4+ incorporated MgAl-layered double hydroxides. J. Colloid Interface Sci. 2007, 313, 53–63. 10.1016/j.jcis.2007.04.004. [DOI] [PubMed] [Google Scholar]
  26. Wang P.; Zhang Y.; Yin Y.; Fan L.; Zhang N.; Sun K. Anchoring hollow MoO2 spheres on graphene for superior lithium storage. Chem. Eng. J. 2018, 334, 257–263. 10.1016/j.cej.2017.10.009. [DOI] [Google Scholar]
  27. Zong E.; Liu X.; Jiang J.; Fu S.; Chu F. Preparation and characterization of zirconia-loaded lignocellulosic butanol residue as a biosorbent for phosphate removal from aqueous solution. Appl. Surf. Sci. 2016, 387, 419–430. 10.1016/j.apsusc.2016.06.107. [DOI] [Google Scholar]
  28. Peng X.; Hu F.; Zhang T.; Qiu F.; Dai H. Amine-functionalized magnetic bamboo-based activated carbon adsorptive removal of ciprofloxacin and norfloxacin: A batch and fixed-bed column study. Bioresour. Technol. 2018, 924–934. 10.1016/j.biortech.2017.10.095. [DOI] [PubMed] [Google Scholar]
  29. Liu H.; Sun X.; Yin C.; Hu C. Removal of phosphate by mesoporous ZrO2. J. Hazard. Mater. 2008, 151, 616–622. 10.1016/j.jhazmat.2007.06.033. [DOI] [PubMed] [Google Scholar]
  30. Su Y.; Cui H.; Li Q.; Gao S.; Shang J. K. Strong adsorption of phosphate by amorphous zirconium oxide nanoparticles. Water Res. 2013, 47, 5018–5026. 10.1016/j.watres.2013.05.044. [DOI] [PubMed] [Google Scholar]
  31. Hao H.; Wang Y.; Shi B. NaLa(CO3)2 hybridized with Fe3O4 for efficient phosphate removal: Synthesis and adsorption mechanistic study. Water Res. 2019, 155, 1–11. 10.1016/j.watres.2019.01.049. [DOI] [PubMed] [Google Scholar]
  32. Du W.; Li Y.; Xu X.; Shang Y.; Gao B.; Yue Q. Selective removal of phosphate by dual Zr and La hydroxide/cellulose-based bio-composites. J. Colloid Interface Sci. 2019, 533, 692–699. 10.1016/j.jcis.2018.09.002. [DOI] [PubMed] [Google Scholar]
  33. Fang D.; Huang L.; Fang Z.; Zhang Q.; Shen Q.; Li Y.; Xu X.; Ji F. Evaluation of porous calcium silicate hydrate derived from carbide slag for removing phosphate from wastewater. Chem. Eng. J. 2018, 354, 1–11. 10.1016/j.cej.2018.08.001. [DOI] [Google Scholar]
  34. Zhang B.; Chen N.; Feng C.; Zhang Z. Adsorption for phosphate by crosslinked/non-crosslinked-chitosan-Fe(III) complex sorbents: Characteristic and mechanism. Chem. Eng. J. 2018, 353, 361–372. 10.1016/j.cej.2018.07.092. [DOI] [Google Scholar]
  35. Tang Q.; Shi C.; Shi W.; Huang X.; Ye Y.; Jiang W.; Kang J.; Liu D.; Ren Y.; Li D. Preferable phosphate removal by nano-La(III) hydroxides modified mesoporous rice husk biochars: Role of the host pore structure and point of zero charge. Sci. Total Environ. 2019, 662, 511–520. 10.1016/j.scitotenv.2019.01.159. [DOI] [PubMed] [Google Scholar]
  36. Zhang L.; Zhou Q.; Liu J.; Chang N.; Wan L.; Chen J. Phosphate adsorption on lanthanum hydroxide-doped activated carbon fiber. Chem. Eng. J. 2012, 185-186, 160–167. 10.1016/j.cej.2012.01.066. [DOI] [Google Scholar]
  37. He Y.; Lin H.; Dong Y.; Wang L. Preferable adsorption of phosphate using lanthanum-incorporated porous zeolite: Characteristics and mechanism. Appl. Surf. Sci. 2017, 426, 995–1004. 10.1016/j.apsusc.2017.07.272. [DOI] [Google Scholar]
  38. Zhang L.; Gao Y.; Zhou Q.; Kan J.; Wang Y. High-Performance Removal of Phosphate from Water by Graphene Nanosheets Supported Lanthanum Hydroxide Nanoparticles. Water, Air, Soil Pollut. 2014, 225, 1967. 10.1007/s11270-014-1967-0. [DOI] [Google Scholar]
  39. Long F.; Gong J.-L.; Zeng G.-M.; Chen L.; Wang X.-Y.; Deng J.-H.; Niu Q.-Y.; Zhang H.-Y.; Zhang X.-R. Removal of phosphate from aqueous solution by magnetic Fe-Zr binary oxide. Chem. Eng. J. 2011, 171, 448–455. 10.1016/j.cej.2011.03.102. [DOI] [Google Scholar]
  40. Awual M. R.; Jyo A.; Ihara T.; Seko N.; Tamada M.; Lim K. T. Enhanced trace phosphate removal from water by zirconium(IV) loaded fibrous adsorbent. Water Res. 2011, 45, 4592–4600. 10.1016/j.watres.2011.06.009. [DOI] [PubMed] [Google Scholar]
  41. Mitrogiannis D.; Psychoyou M.; Baziotis I.; Inglezakis V. J.; Koukouzas N.; Tsoukalas N.; Palles D.; Kamitsos E.; Oikonomou G.; Markou G. Removal of phosphate from aqueous solutions by adsorption onto Ca(OH)2 treated natural clinoptilolite. Chem. Eng. J. 2017, 320, 510–522. 10.1016/j.cej.2017.03.063. [DOI] [Google Scholar]
  42. Apte S. K.; Naik S. D.; Sonawane R. S.; Kale B. B.; Baeg J. O. Synthesis of nanosize-necked structure α- and γ-Fe2O3 and its photocatalytic activity. J. Am. Ceram. Soc. 2007, 90, 412–414. 10.1111/j.1551-2916.2006.01424.x. [DOI] [Google Scholar]
  43. Cui H.; Li Q.; Gao S.; Shang J. K. Strong adsorption of arsenic species by amorphous zirconium oxide nanoparticles. J. Ind. Eng. Chem. 2012, 18, 1418–1427. 10.1016/j.jiec.2012.01.045. [DOI] [Google Scholar]
  44. Lǚ J.; Liu H.; Liu R.; Zhao X.; Sun L.; Qu J. Adsorptive removal of phosphate by a nanostructured Fe-Al-Mn trimetal oxide adsorbent. Powder Technol. 2013, 233, 146–154. 10.1016/j.powtec.2012.08.024. [DOI] [Google Scholar]
  45. Dou X.; Mohan D.; Pittman C. U. Jr.; Yang S. Remediating fluoride from water using hydrous zirconium oxide. Chem. Eng. J. 2012, 198-199, 236–245. 10.1016/j.cej.2012.05.084. [DOI] [Google Scholar]
  46. Wang J.; Lin X.; Luo X.; Long Y. A sorbent of carboxymethyl cellulose loaded with zirconium for the removal of fluoride from aqueous solution. Chem. Eng. J. 2014, 252, 415–422. 10.1016/j.cej.2014.05.008. [DOI] [Google Scholar]
  47. Wang J.; Tong X.; Wang S. Zirconium-Modified Activated Sludge as a Low-Cost Adsorbent for Phosphate Removal in Aqueous Solution. Water, Air, Soil Pollut. 2018, 229, 47. 10.1007/s11270-018-3704-6. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

ao0c03657_si_001.pdf (294.6KB, pdf)

Articles from ACS Omega are provided here courtesy of American Chemical Society

RESOURCES