Dataset on the degradation of losartan by TiO₂-photocatalysis and UVC/persulfate processes

Abstract

Losartan is a highly consumed antihypertensive worldwide and commonly found in effluents of municipal wastewater treatment plants. In the environment, losartan can promote harmful effects on organisms. Thus, an option to face this pollutant is the treatment by photochemical advanced oxidation processes. This dataset has two main components: 1) theoretical calculations on reactivity indexes for losartan, and 2) degradation of the pollutant throughout TiO₂-photocatalysis and UVC/persulfate (UVC/PS). The first part of the work presents the data about HOMO and LUMO energies, optimized geometry, dipolar moment, HOMO/LUMO energy gap and total density distribution, in addition to ionization energy, electron affinity, chemical potential, hardness, softness and electrophilicity for losartan. Meanwhile, the second one depicts information on the routes involved in the degradation of the pharmaceutical by the oxidation processes, mineralization, toxicity evolution and losartan removal from a complex matrix (synthetic fresh urine). The data reported herein may be utilized for further researches related to elimination of pharmaceuticals in primary pollution sources such as urine. Moreover, this work also provides experimental and theoretical data useful for the understanding of the response of losartan to oxidative and photochemical processes.

Specifications table

Subject	Environmental chemistry
Specific subject area	Advanced oxidation process
Type of data	Table Figure
How data were acquired	Data were acquired by using HPLC-DAD and Gaussian 09 (software of quantum chemistry), Method: ground state, DFT, B3LYP, Basis: 6-311g ++ (2d, 2p).
Data format	Raw Analyzed
Parameters for data collection	The experiments were carried out at fixed operational conditions to establish the capability of TiO2-photocatalysis and UVC/Persulfate to degrade a highly consumed antihypertensive.
Description of data collection	The degradation at lab-scale of the antihypertensive losartan (LOS) by two photochemical process was performed. Initially, computational calculations on LOS were carried out. Then, the treatment in distilled water was done and the routes of process action were determined by using scavengers. Afterwards, data about mineralization and toxicity evolution were obtained. Finally, the information on matrix effect by LOS degradation in synthetic fresh urine was attained.
Data source location	Universidad de Antioquia UdeA, Medellín, Colombia; Universidad Santiago de Cali, Cali, Colombia; Universidad Tecnológica de Pereira, Pereira, Colombia
Data accessibility	Mendeley data repository through the following link: https://data.mendeley.com/datasets/7pbnd4vvm5/draft?a=a3dc88ff-086e-4baf-93b6-ab49d900e8cd

Value of the data

• •Data are useful to analyze similarities and differences between TiO₂-photocatalysis and UVC/Persulfate for degrading pharmaceuticals such as losartan antihypertensive.
• •Data can benefit people researching on elimination of antihypertensives by photochemical advanced oxidation processes in aqueous matrices.
• •Data can be utilized for further insights about degradation of pharmaceuticals in a complex matrix, such as hospital effluents.
• •Data are valuable for future works on oxidation processes, photochemistry and organic reactions of losartan.

1. Data Description

Dataset presented in this work have two main parts, the first component deals with computational calculations on losartan and the second one contains information about the degradation of the pharmaceutical by two advanced oxidation processes (i.e., TiO₂-photocatalysis and UVC/persulfate). These photochemical processes are widely used for degrading organic pollutants in aqueous matrices [1], [2], [3], [4].

It should be mentioned that for double bonds in alkenes and aromatic rings (as contained in losartan structure), frontier orbitals (i.e., highest occupied molecular orbital-HOMO and in the lowest unoccupied molecular orbital-LUMO) can be useful to predict radical attack positions [5]. Then, energies of HOMO and LUMO, in addition to optimized geometry, dipolar moment, HOMO/LUMO energy gap and total density distribution, were theoretically stated, this information is presented in Table 1, Table 2. Meanwhile, Table 3 contains other reactivity indexes (such as ionization energy, electron affinity, chemical potential, hardness, softness and electrophilicity) for losartan.

Table 1.

Computational calculations for losartan.

Parameter	Results
Chemical structure of losartan
Total energy
Dipolar moment
Highest occupied molecular orbital (HOMO)
Lowest unoccupied molecular orbital (LUMO)
Gap energy (EGAP)	2.02 eV
Total density distribution

Table 2.

Total density distribution for losartan.

Moiety	Atom	Densities	Atoms numeration
Imidazole	1 C	-0.013722
	2 C	0.123255
	3 C	-2.42648
	4 N	0.053696
	5 H	0.179991
	6 N	0.310516
Chlorine	7 Cl	-0.046173
Alcohol	8 C	-0.72382
	9 H	0.101355
	10 H	0.143965
	11 O	-0.458425
	12 H	0.3764
Biphenyl	13 C	0.294884
	14 H	0.099872
	15 H	0.102713
	16 C	0.548818
	17 C	-0.382691
	18 C	-0.470243
	19 C	-0.512244
	20 H	0.136655
	21 C	-0.637257
	22 H	0.150577
	23 C	0.667093
	24 H	0.168494
	25 H	0.175748
	26 C	0.391657
	27 C	0.446463
	28 C	-0.177684
	29 C	-0.194079
	30 C	-0.374148
	31 H	0.169917
	32 C	-0.404455
	33 H	0.169726
	34 H	0.160523
	35 H	0.154444
Tetrazole	36 C	-0.005707
	37 N	-0.290324
	38 N	-0.354756
	39 N	0.004876
	40 N	0.12792
	41 H	0.302545
Butyl	42 C	1.416066
	43 C	-0.575332
	44 H	-0.001771
	45 H	0.034663
	46 C	-0.046357
	47 H	0.078481
	48 H	0.05442
	49 C	-0.479371
	50 H	0.076031
	51 H	0.069222
	52 H	0.103527
	53 H	0.090485
	54 H	0.090042

Table 3.

Reactivity indexes for losartan.

Ionization energy (eV)	Electron affinity (eV)	Chemical potential (eV)	Global Hardness (eV)	Local softness (eV)	Global index of electrophilicity (eV)
2.2005	2.1434	2.1719	0.0571	17.513	42.062

Regarding losartan degradation by the AOPs, in Fig. 1 is shown the antihypertensive evolution during the treatment in distilled water using TiO₂-photocatalysis (TiO₂ PC). Fig. 1 also presents data on removal by photolysis (UVA), the pollutant degradation in presence of potassium iodide and isopropanol scavengers (TiO₂ PC/KI and TiO₂ PC/IPA, respectively) and replacing water media by acetonitrile solvent (TiO₂ PC/ACN) to provide information about the routes involved in the process [1,2]. In turn, Fig. 2 presents the degradation of losartan by the UVC/PS system, control experiments (action of persulfate-PS or the light-UVC), plus the dataset for experiments when isopropanol (UVC/PS/IPA, which is a scavenger of hydroxyl and sulfate radicals [6]) is added.

Fig. 1.

Degradation of losartan using TiO₂-photocatalysis (TiO₂ PC). [Losartan]= 43.38 µmol L^-1, initial pH: 6.1, [TiO₂] = 0.5 g L^-1, [KI]= [IPA]= 4.33 mmol L^-1 and UVA light power = 75 W.

Fig. 2.

Degradation of losartan by the UVC/PS process. [Losartan]= 43.38 µmol L^-1, initial pH: 6.1, [PS] = 500 µmol L^-1, [IPA]= 4.33 mmol L^-1 and UVC light power = 60 W.

In Fig. 3 is presented the evolution of total organic carbon (TOC) and phytotoxicity under the two processes, for comparative purposes, the TOC removal (Fig. 3A) and toxicity (Fig. 3B) were measured at two normalized times: 1 (when losartan is 100% degraded) and 2 (the double of time required to 100% remove the antihypertensive). Fig. 4. compares the treatment of losartan in distilled water and synthetic fresh urine by TiO₂-photocatalysis (Fig. 4A) and UVC/PS (Fig. 4B) processes. Table 4 depicts the synthetic fresh urine composition and Table 5 summarizes the literature search on the interaction/reaction among hydroxyl or sulfate radicals with the urine components, in addition to the pseudo-first order rate constants for losartan degradation by TiO₂-photocatalysis and UVC/PS.

Fig. 3.

Extension of advanced oxidation treatments. A. Mineralization of losartan during application of the different processes. B. Toxicity against radish seeds (Raphanus sativus) of treated solution of losartan. Experimental conditions as described in Figs. 1 and 2.

Fig. 4.

Comparison of losartan degradation in distilled water (DW) and simulated fresh urine (Urine). A. TiO₂ photocatalysis. B. UVC/PS process. Experimental conditions as described in Figs. 1 and 2.

Table 4.

Composition of synthetic fresh urine ([7]) used for the experiments.

Compound	Concentration (mol L-1)
Urea	0.2664
CH3COONa	0.1250
Na2SO4	0.01619
NH4Cl	0.03365
NaH2PO4	0.02417
KCl	0.05634
MgCl2	0.003886
CaCl2	0.004595
NaOH	0.00300
pH = 6.1

Table 5.

Rate constants of the reactions between the radical species and the components of fresh urine.

Reaction	Second order rate constant (k2nd, L mol-1 s-1)	References
$H{O}^{•}+C{l}^{-}\to ClO{H}^{•-}$	4.3x109	[8]
$H{O}^{•}+H_{2}P{O}_4^{-}\to H{O}^{-}+H_{2}P{O}_4^{•}$	∼ 2x104	[9]
$H{O}^{•}+C{H}_{3}CO{O}^{-}\to H_{2}O+C{H}_{2}CO{O}^{•-}$	7.0 x107	[10]
$H{O}^{•}+O{H}^{-}\to O^{•}+H_{2}O$	1.3x1010	[11]
$H{O}^{•}+H_{2}NCON{H}_2\to products$	7.9x105	[9]
$H{O}^{•}+S{O}_4^{2-}\to S{O}_4^{•-}+H{O}^{-}$	6.5x102	[3]
$S{O}_4^{•-}+C{l}^{-}\to S{O}_4^{2-}+C{l}^{•}$	3.1×108	[4]
$S{O}_4^{•-}+O{H}^{-}\to S{O}_4^{2-}+H{O}^{•}$	6.5x107	[12]
$S{O}_4^{•-}+N{H}_4^{+}/N{H}_3\to products$	3.5×105	[13]
$S{O}_4^{•-}+C{H}_{3}C{O}_2^{-}\to S{O}_4^{2-}{+}^{•}C{H}_3+C{O}_2({+}^{•}C{H}_{2}C{O}_2^{-}$)	5.8x106	[14]
$S{O}_4^{•-}+H_{2}P{O}_4^{-}\to products$	< 7x104	[13]
Pseudo-first order rate constant (k, min-1) for degradation of losartan by the processes
TiO2-photocatalysis	0.004	In this work
UV/PS	0.029	In this work

2. Experimental Design, Materials, and Methods

2.1. Reagents

Acetonitrile, isopropanol, methanol, potassium iodide, potassium persulfate, sodium acetate, sodium chloride, sodium dihydrogen phosphate, sodium hydroxide, sodium sulfate, and urea were provided by Merck. Ammonium chloride, formic acid, calcium chloride and magnesium chloride were provided by PanReac. Titanium dioxide was provided by Evonik. Losartan was purchased from La Santé S.A. The solutions of losartan were prepared using distilled water. In all cases, the initial losartan concentration was 43.38 µmol L^-1.

2.2. Reaction systems

A homemade aluminum reflective reactor containing UVC lamps (OSRAM HNS®, 60 W of light power) with main emission at 254 nm was used for the UVC/PS process. Losartan solutions (50 mL) were placed in beakers (100 mL of capacity) under constant stirring. The TiO₂-photocatalysis process was carried out in the same reactor but equipped with UVA lamps (Philips BLB, 75 W of light power) having main emission peak at 365 nm. Losartan solutions (50 mL) were also placed in beakers under constant stirring. Additionally, the adsorption/desorption equilibrium on TiO₂ catalyst was reached after 30 min in dark.

Aliquots of 0.5 mL were taken periodically from the rectors for kinetics analyses by UHPLC (no more than nine aliquots were considered to avoid modifications of the sample volume higher than 10%). For total organic carbon and toxicity measurements, independent experiments were performed and the whole sample was considered in each case per point of the analyses.

2.3. Analyses

Losartan evolution was determined by means a UHPLC Thermo Scientific Dionex UltiMate 3000 chromatograph equipped with an Acclaim™ 120 RP C18 column (5 µm, 4.6 x150 mm) and a DAD (operated at 230 and 254 nm). The mobile phase was methanol/acetonitrile/formic acid (10 mM and pH 3.0) at 10/44/46 %v/v at 0.6 mL min^-1.

Mineralization was established using 10 mL of sample by measuring of total organic carbon (TOC), through a Shimadzu LCSH TOC analyzer (previously calibrated), according to Standard Methods 5310, by combustion with catalytic oxidation at 680 °C using high-purity oxygen gas at a flow rate of 190 mL/min. The apparatus had a non-dispersive infrared detector.

Toxicity against radish seeds (Raphanus sativus) was established by interaction of target solution with the indicator seeds. The solution to be tested (5 mL) was placed in a petri dish; then, ten (10) Raphanus sativus seeds were submerged into the solution. The seeds and solution were in contact during 72 h. Afterward, the length of germinated plants was measured, subsequently a mean value and standard deviation for each tested solution were calculated.

The computational calculations were done by using Gaussian 09 (quantum chemistry software); Method: ground state, DFT, B3LYP; Basis: 6-311g ++ (2d, 2p) [15]. The neutral molecule was considered using the dielectric constant for water.