From rust to robust disinfectants: How do iron oxides and inorganic oxidants synergize with UVA light towards bacterial inactivation?

Pathogens in drinking water remain a challenge for human health, photo-Fenton process is a promising technique for pathogen inactivation, herein, two common iron oxides, hematite and magnetite mediate persulfate (peroxymonosulfate-PMS - and peroxydisulfate-PDS) involved photo-Fenton-like processes were constructed for E. coli inactivation, and the inactivation performance was investigated and compared with the photo-Fenton process under a low intensity UVA irradiation. Results indicated that with a low dose of iron oxides (1 mg/L) and inorganic peroxides (10 mg/L), PMS-involved photo-Fenton-like process is the best substitute for the photo-Fenton one over pH range of 5-8. In addition, humic acid (HA, one of the important components of natural organic matter) incorporated iron oxide-mediated photo-Fenton-like processes for bacteria inactivation was also studied, and facilitating effect was found in UVA/hematite/PMS and UVA/magnetite/PDS systems. Reactive oxygen species (ROS) exploration experiments revealed that ·OH was the predominant radical in H2O2- and PDS-containing systems, whereas 1O2 was one of the principal reactive species in the PMS systems. In addition to the semiconductor photocatalysis of iron oxides and UVA-activated oxidants, iron-complexes (iron-oxidant complexes and iron-bacteria complexes) mediated ligand-to-metal charge transfer (LMCT) processes also made contribution to bacterial inactivation. Overall, this study demonstrates that it is feasible to replace H2O2 with PMS in a photo-Fenton-like process for water disinfection using a low dose of reagents, mediated by cheap catalysts, such as hematite and magnetite, it is also hoped to provide some insights to practical water treatment.

Acids from fruits generate photoactive Fe-complexes, enhancing solar disinfection of water (SODIS): A systematic study of the novel "fruto-Fenton" process, effective over a wide pH range (4 - 9).

This study aimed to enhance solar disinfection (SODIS) by the photo-Fenton process, operated at natural pH, through the re-utilization of fruit wastes. For this purpose, pure organic acids present in fruits and alimentary wastes were tested and compared with synthetic complexing agents. Owing to solar light, complexes between iron and artificial or natural chelators can be regenerated through ligand-to-metal charge transfer (LMCT) during disinfection. The target complexes were photoactive under solar light, and the Fe:Ligand ratios for ex situ prepared iron complexes were assessed, achieving a balance between iron solubilization and competition with bacteria as a target for oxidizing species. In addition, waste extracts containing natural acidic ligands were an excellent raw material for our disinfection enhancement purposes. Indeed, lemon and orange juice or their peel infusions turned out to be more efficient than commercially available organic acids, leading to complete inactivation in less than 1 h by this novel "fruto-Fenton" process, i.e. in the presence of a fruit-derived ligand, Fe(II) and H2O2. Finally, its application in Lake Leman water and in situ complex generation led to effective bacterial inactivation, even in mildly alkaline surface waters. This work proposes interesting SODIS and fruit-mediated photo-Fenton enhancements for bacterial inactivation in resource-poor contexts and/or under the prism of circular economy.

Why is HSO5- so effective against bacteria? Insights into the mechanisms of Escherichia coli disinfection by unactivated peroxymonosulfate.

This study examined the antimicrobial efficacy of peroxymonosulfate (PMS) against bacteria, using Escherichia coli (E. coli) as a model organism. Our investigation delineates the complex mechanisms exerted by unactivated PMS. Thus, an initial redox reaction between PMS and the target biomolecules of bacteria generates SO4•- as the pivotal reactive species for bacterial inactivation; to a lesser extent, •OH, 1O2, or O2•- may also participate. Damage generated during oxidation was identified using an array of biochemical techniques. Specifically, redox processes are promoted by PMS and SO4•- targets and disrupt various components of bacterial cells, predominantly causing extracellular damage as well as intracellular lesions. Among these, external events are the key to cell death. Finally, by employing gene knockout mutants, we uncovered the role of specific gene responses in the intracellular damage induced by radical pathways. The findings of this study not only expand the understanding of PMS-mediated bacterial inactivation but also explain the ten-fold higher effectiveness of PMS than that reported for H2O2. Hence, we provide clear evidence that unactivated PMS solutions generate SO4•- in the presence of bacteria, and consequently, should be considered an effective disinfection method.

The silver lining of antibiotic resistance: Bacterial-mediated reduction of tetracycline plant stress via antibiotrophy.

The reuse of water using effluents containing antibiotics from anthropogenic activities has been mainly linked to the development of antibiotic resistance. However, we report that the development of bacterial tolerance promotes plant growth. In the present study, we aimed to evaluate the efficiency of inoculation of a new antibiotic-degrading bacterium, Erwinia strain S9, in augmenting the tolerance of pea (Pisum sativum L.) plants to tetracycline (TET) (10 and 20 mg/L). Physiological parameters such as tissue elongation and biomass, as well as relative water content, were remarkably lower in plants exposed to TET than in the control. The inhibitory effects of TET were associated with reduced CO2 assimilation, stomatal conductance, transpiration, dark respiration, and light saturation point (LSP). High concentrations of TET-induced oxidative stress are attested by the overproduction of superoxide radicals (O2•-), hydrogen peroxide (H2O2), and hydroxyl radicals (HO•), resulting in increased malondialdehyde content and cell death. The high activity of antioxidant enzymes such as catalase, ascorbate peroxidase, and guaiacol peroxidase validated the proposed mechanism. Under TET stress conditions, supplementation with Erwinia strain S9 was beneficial to pea plants through osmotic adjustment, increased nutrient uptake, gas exchange optimization, and increased antioxidant activities. Its presence not only ensures plant survival and growth during antibiotic stress but also degrades TET via significant antibiotrophy. This strategy is a cost-effective environmental chemical engineering tool that can be used to depollute wastewater or to improve crop resistance in rhizofiltration treatment when treated wastewater is reused for irrigation.

Efficient and sustainable photocatalytic inactivation of E. coli by an innovative immobilized Ag/TiO2 photocatalyst with peroxymonosulfate (PMS) under visible light.

A novel catalytic system for effective photocatalytic inactivation of Escherichia coli (E. coli) was constructed by anchoring Ag nanoparticles (AgNPs) on silane coupling agent (SCA) pretreated TiO2 nano-tube arrays (Ag/SCA/TiO2NTAs). Morphology and structural analyses revealed that SCA could disperse AgNPs evenly on TiO2NTAs, thus inducing a superior surface plasmon resonance (SPR) effect. Ag/SCA/TiO2NTAs catalyst exhibited excellent inactivation performance when in the presence of peroxymonosulfate (PMS) and visible light (VL), with 6-log E. coli was completely inactivated within 60 min, which was 5.3, 12.5 and 13.2 times higher than that of Ag/SCA/TiO2NTAs/VL, PMS/VL and Ag/SCA/TiO2NTAs/PMS/dark systems, respectively. Additionally, the photocatalyst exhibited a highly reusable property, with the inactivation performance almost unchanged after ten cycles of uses with minimal Ag leaching. The inactivation mechanism analysis demonstrated that both radical (SO4•-, OH) and non-radical (h+, 1O2) pathways involved in E. coli inactivation, and SCA played a pivotal role in the production of reactive species. Chloride ions (Cl-) greatly enhanced the inactivation efficiency, while bicarbonate (HCO3-) and phosphate (H2PO4-) showed an inhibitory effect. Humic acid (HA) displayed a dual effect on inactivation performance, where the low concentration of HA facilitated the bacteria inactivation, while the higher dose suppressed bacteria inactivation. Moreover, the system exhibited excellent inactivation performance in tap water. This work first used SCA as the binder to fix AgNPs on TiO2NTAs for VL photocatalytic inactivation of bacteria with the assistance of PMS, which was expected to provide some insights into the practical treatment of drinking water.

Peroxymonosulfate assisted pesticide breakdown: Unveiling the potential of a novel S-scheme ZnO@CoFe2O4 photo-catalyst, anchored on activated carbon.

A ternary hetero-junction was prepared by anchoring ZnO@CoFe2O4 (ZCF) on activated carbon (AC) and employed as a UV-assisted peroxymonosulfate (PMS) activator to boost the degradation of diazinon (DZN) pesticide. The structure, morphology, and optical properties of the ZCFAC hetero-junction were characterized through a series of techniques. The highest degradation efficiency of DZN (100% in 90 min) was achieved by the PMS-mediated ZCFAC/UV system, superior to other single or binary catalytic systems due to the strong synergistic effect between ZCFAC, PMS, and UV. The operating reaction conditions, synergistic effects, and the possible pathways of DZN degradation were investigated and discussed. Optical analysis showed that the band-gap energy of the ZCFAC hetero-junction not only enhanced the absorption of UV light but also reduced the recombination of photo-induced electron/hole pairs. Both radical and non-radical species (HO•, SO4•-, O2•-, 1O2, and h+) took part in the photo-degradation of DZN, assessed by scavenging tests. It was found that AC as a carrier not only improved the catalytic activity of CF and ZnO nanoparticles and conferred high stability for the catalyst but also played a crucial role in accelerating the catalytic PMS activation mechanism. Moreover, the PMS-mediated ZCFAC/UV system showed good reusability, universality, and practical applicability potential. Overall, this work explored an efficient strategy for the best use of hetero-structure photo-catalysts towards PMS activation to achieve high performance in decontaminating organic compounds.

Putting the electro-bugs to work: A systematic review of 22 years of advances in bio-electrochemical systems and the parameters governing their performance.

Wastewater treatment using bioelectrochemical systems (BESs) can be considered as a technology finding application in versatile areas such as for renewable energy production and simultaneous reducing environmental problems, biosensors, and bioelectrosynthesis. This review paper reports and critically discusses the challenges, and advances in bio-electrochemical studies in the 21st century. To sum and critically analyze the strides of the last 20+ years on the topic, this study first provides a comprehensive analysis on the structure, performance, and application of BESs, which include Microbial Fuel Cells (MFCs), Microbial Electrolysis Cells (MECs) and Microbial Desalination Cells (MDCs). We focus on the effect of various parameters, such as electroactive microbial community structure, electrode material, configuration of bioreactors, anode unit volume, membrane type, initial COD, co-substrates and the nature of the input wastewater in treatment process and the amount of energy and fuel production, with the purpose of showcasing the modes of operation as a guide for future studies. The results of this review show that the BES have great potential in reducing environmental pollution, purifying saltwater, and producing energy and fuel. At a larger scale, it aspires to facilitate the path of achieving sustainable development and practical application of BES in real-world scenarios.

Establishing the relationship between Polycyclic Aromatic Hydrocarbons (PAHs) exposure and male infertility: A systematic review.

It has been demonstrated that human exposure to environmental chemicals may have sperm genotoxic potentiality. Among the different classes, Polycyclic Aromatic Hydrocarbons (PAHs) have been receiving attention in recent years due to reports of sperm geno-toxicity, a series of reproductive defects and male infertility. This review aims to substantiate the effects of PAHs exposure on male infertility, with focus on the sperm characteristics (count, concentration, volume, motility, DNA damage, and morphology). To this end, international databases such as Cochrane Library, PubMed, Web of Science, Embase Ovid, Scopus, and Google Scholar were used to conduct a systematic search for papers on the subject, based on PRISMA guidelines, published up to 24 March 2022. The Newcastle-Ottawa Scale was subsequently used to assess the quality of the studies. The results showed that there is a significant negative relationship between PAHs metabolites and sperm volume, concentration, motility, morphology, as well as an observed DNA degeneration. Also, the CYP1A1 genotype polymorphisms were considered as a representative of PAHs exposure to infertility; the review highlights that polymorphisms of this genotype were more common in the infertile people. In overall, this work provides a solid summary of the existing works correlating PAHs exposure and male infertility, which could impulse further protective measures and informative campaigns on users, workers, and general population.

Anchoring ZnO on spinel cobalt ferrite for highly synergic sono-photo-catalytic, surfactant-assisted PAH degradation from soil washing solutions.

In this study, the photocatalytic activity of ZnO was effectively improved via its combination with spinel cobalt ferrite (SCF) nanoparticles. The catalytic performance of ZnO@SCF (ZSCF) was investigated in coupling with UV irradiation and ultrasound (US), as a heterogeneous sono-photocatalytic process, for the decontamination of phenanthrene (PHE) from contaminated soil. Soil washing tests were conducted in a batch environment, after extraction assisted by using Tween 80. Several characterization techniques such as XRD, FESEM-EDS, BET, TEM, UV-vis DRS, PL and VSM were utilized to determine the features of the as-prepared catalysts. ZSCF showed an excellent catalytic activity toward degradation of PHE in the presence of US and UV with a significant synergic effect. It was found that more than 93% of PHE (35 mg/L) and 87.5% of TOC could be eliminated by the integrated ZSCF/US/UV system under optimum operational conditions (pH: 8.0, ZSCF: 1.5 g/L, UV power: 6.0 W and US power: 70 W) within 90 min of reaction. After five times of use, ZSCF illustrated good reusability in the decontamination of PHE (87%) and TOC (79%). Quenching tests revealed the contribution of h+, HO• and e- species during PHE degradation over ZSCF/UV/US and an S-scheme photocatalytic mechanisms was proposed for the possible charge transfer routes under the ZSCF system. This study provides the important role of SCF in enhancing the ZnO photocatalytic activity due to its high performance, easy recovery and excellent durability, which it make an efficient and promising catalyst in environmental clean-up applications.

Improved catalytic performance of ZnO via coupling with CoFe2O4 and carbon nanotubes: A new, photocatalysis-mediated peroxymonosulfate activation system, applied towards Cefixime degradation.

In this study, a ternary ZnO@spinel cobalt ferrite@carbon nanotube magnetic photocatalyst (ZSCF@CNT) was successfully synthesized and used to activate peroxymonosulfate (PMS) for Cefixime (CFX) antibiotic degradation under UVC irradiation. The morphology, optical, structural, and physicochemical properties of ZSCF@CNT were characterized and analyzed by XPS, XRD, FESEM-EDX, TEM, BET, VSM, UV-vis DRS and PL analysis. The results indicated that the ternary ZSCF@CNT photocatalyst exhibited superior catalytic activity on CFX elimination than that of individual components and binary composite catalysts, in which CFX with was rapidly removed under UVC irradiation and PMS. The effect of operational parameters including initial PMS, catalyst, and CFX concentrations and solution pH on the catalytic activity was investigated in detail; the optimal conditions were: pH: 7.0, catalyst: 0.3 g/L, PMS: 3.0 mM, leading to total CFX (10 mg/L) elimination in ∼20 min. Based on the radical scavenger tests, various radicals and non-radical species including sulfate, hydroxyl and superoxide radicals, singlet oxygen and electrons were involved in the ZSCF@CNT/PMS/UVC system. The high surface area, reduced agglomeration formation and excellent separation of photogenerated electron-hole pairs embodied in ZSCF@CNT photocatalyst conferred its superior catalytic activity and stability. The results from the tests in real water matrices revealed that ZSCF@CNT could be a promising photocatalyst to activate PMS for actual aqueous matrices' treatment.

Effective removal of the rotifer Brachionus calyciflorus from a Chlorella vulgaris microalgal culture by homogeneous solar photo-Fenton at neutral pH.

In this study, a citrate-modified photo-Fenton process was successfully applied to decontaminate a Chlorella vulgaris microalgae culture spiked with the rotifer Brachionus calyciflorus (5 individuals mL-1). The applied treatment (1 mg L-1 Fe2+, 20 mg L-1 H2O2, 17.5 mg L-1 citric acid) had only moderate effects on viability and regrowth of the microalgae since, after a short post-treatment delay of a few days, they reached final cell densities similar to that obtained for microalgae cultures that were not spiked. The decontamination was effective as no regrowth of rotifers was observed in the microalgae cultures after treatment. The efficacy of the citrate-modified photo-Fenton treatment was also studied with a higher starting concentration of 20 rotifers mL-1 and was compared with a solar light/H2O2 treatment. Results show that both treatments had similar efficacies on the rotifer elimination, but that the citrate-modified photo-Fenton treatment had a lower negative impact on the regrowth of microalgae than the solar light/H2O2 treatment. However, when microalgae cultures were spiked with 20 rotifers mL-1, rotifers were only partially inactivated and post-treatment regrowth occurred, which highlights the importance to apply the photo-Fenton process at an early stage of a contamination to achieve full rotifer elimination. In any case, a contamination with 5 rotifers mL-1 is already a significant threat as numbers above 1000 rotifers mL-1 were reached after 14 days and caused the microalgae culture to fail. Overall, our treatment suggests that the citrate-modified solar photo-Fenton process is an environmentally friendly solution to support the maintenance of contaminant-free microalgal cultures.

Potential of nanochitosan coating combined with walnut green husk to improve the preservation of rainbow trout (Oncorhynchus mykiss) during refrigerated storage.

The present study evaluated the potential of nanochitosan coating enriched with ethanol-water extract of the walnut green husk (WGHE) on spoilage and rancidity of rainbow trout (Oncorhynchus mykiss) during six-day refrigerated storage. Hence, we have considered fresh trout fillets without any treatment as control (C), immersed in 2% solution of chitosan nanoparticles (CN), combination with 1.5% and 3% WGHE with nanochitosan coating (CN + WGHE 1.5 and CN + WGHE3), for physicochemical, microbial and sensorial assays. The highest levels and total volatile nitrogen were observed after day 6 in C, while the lowest was found in CN + WGHE3 groups. Thiobarbituric acid reactive substance (TBARS) and peroxide value of untreated fillets on day 6 of the study were significantly higher than NC + WGHE3 with 0.08 mg/g and 3.27 mEq/kg, respectively. The total microbial population was: C ˃ CN ˃ CN + WGHE 1.5 > CN + WGHE3, which expresses the effect of the extract on the total microbial population. Overall, the combination of WGHE with CN increased the extract's efficiency in reducing peroxide value, TBARS, and total volatile nitrogen and delayed the pH increase, improving the overall acceptability of rainbow trout fillets stored in refrigerated conditions.

A novel, Z-scheme ZnO@AC@FeO photocatalyst, suitable for the intensification of photo-mediated peroxymonosulfate activation: Performance, reactivity and bisphenol A degradation pathways.

In this study, the intensification of a UVC-based PMS activation treatment is performed by a novel photocatalyst. Using ZnO nanoparticles coupled with activated carbon (AC), impregnated by ferroferric oxides (FO, magnetite), as an effective Z-scheme photocatalyst (ZACFO), the effective Bisphenol A (BP-A) removal was attained. Several techniques were applied for the characterization of the as-prepared catalyst and proved the successful preparation of ZACFO. The photocatalytic activity of pristine ZnO was significantly improved after its combination with ACFO. It was found that the fabrication of ZACFO heterostructures could inhibit the charge carriers recombination and also accelerate the charge separation of photo-induced e-/h+ pairs. Under this UVC-based photocatalysis-mediated PMS activation system, ZACFO showed an excellent potential as compared to the single constituent catalysts. The complete degradation of 20 mg/L concentration of BP-A was attained in just 20 min with excellent reaction rate constant of 27.3 × 10-2 min-1. Besides, over 60% of TOC was eliminated by the integrated ZACFO/PMS/UV system within 60 min of reaction. The minor inhibition by most matrix components, the high recycling capability with minor metals' leaching and the effectiveness in complex matrices, constitute this composite method an efficient and promising process for treating real wastewater samples. Finally, based on the photo-produced reactive intermediates and by-products identified, the Z-scheme photocatalytic mechanism and the plausible pathway of BP-A degradation were proposed comprehensively. The presence and role of radical and non-radical pathways in the decontamination process of BP-A over ZACFO/PMS/UV system was confirmed.

Exploring the visible light-assisted conversion of CO2 into methane and methanol, using direct Z-scheme TiO2@g-C3N4 nanosheets: synthesis and photocatalytic performance.

The rapid growth of carbon dioxide (CO2) emissions raises concern about the possible consequences of atmospheric CO2 increase, such as global warming and greenhouse effect. Photocatalytic CO2 conversion has attracted researchers' interests to find a sustainable route for its elimination. In the present study, a direct Z-scheme TiO2/g-C3N4 composite (T-GCN) was fabricated via a facile hydrothermal route for the photocatalytic reduction of CO2 into methane (CH4) and methanol (CH3OH), under visible light irradiation without an electron mediator. The microstructure of the as-obtained TiO2/g-C3N4 nanocomposites was fully characterized for its physicochemical, structural, charge separation, electronic, and photo-excited carrier separation properties. The effect of CO2 and H2O partial pressure was studied to find the best operational conditions for obtaining maximum photocatalytic efficiency; the PCO2 and PH2O were 75.8 and 15.5 kPa, respectively, whereas, by increasing the light intensity from 20 to 80 mW/cm2, a remarkable improvement in the reduction rate takes place (from 11.04 to 32.49 µmol.gcat-1.h-1 methane production, respectively). Finally, under the most favorable light, PCO2 and PH2O conditions, high methanol and methane rates were obtained from the CO2 photocatalytic reduction through T-GCN (1.44 µmol.gcat.-1.h-1 and 32.49 µmol.gcat.-1.h-1, respectively) and an integrated proposition for the Z-scheme mechanism of photocatalytic reduction was proposed. This study offers a promising strategy to synthesize a Z-scheme T-GCN heterojunction with high photocatalytic performance for effective CO2 conversion.

The efficacy of the VUV/O3 process run in a continuous-flow fluidized bed reactor for simultaneous elimination of favipiravir and bacteria in aqueous matrices.

The efficacy of the Vacuum UV/Ozonation (VUV/O3) process was evaluated for the degradation of favipiravir (FAV). It was found that coupling O3 and VUV resulted in a considerable synergistic catalytic effect on FAV removal. The VUV/O3 process performed better in moderately alkaline conditions than in acidic ones; complete FAV degradation and 99.4% TOC removal were achieved within 10 and 60 min, respectively. HO• played the dominant role in FAV degradation, with a second-order reaction rate constant with HO• at 1.05 × 1010 M-1 s-1. The VUV/O3 process could effectively treat tap water spiked with FAV. Efficient FAV and TOC removal, as well as total bacterial inactivation, was attained when treating municipal secondary effluent by the VUV/O3 process. Finally, the VUV/O3 process was operated in a continuous-flow mode in a fluidized-bed (FBR) reactor for treating FAV-spiked tap water. Complete degradation and 75.1% mineralization of 10 mg/L FAV were obtained at a hydraulic retention time of 1 and 8 min, respectively. The findings clearly suggest that the VUV/O3 process operated in a continuous-flow FBR is a promising, efficient technology for the removal of novel and emerging contaminants, such as the antiviral FAV.

Identifying the mediators of intracellular E. coli inactivation under UVA light: The (photo) Fenton process and singlet oxygen.

Solar disinfection (SODIS) was probed for its underlying mechanism. When Escherichia coli was exposed to UVA irradiation, the dominant solar fraction acting in SODIS process, cells exhibited a shoulder before death ensued. This profile resembles cell killing by hydrogen peroxide (H2O2). Indeed, the use of specialized strains revealed that UVA exposure triggers intracellular H2O2 formation. The resultant H2O2 stress was especially impactful because UVA also inactivated the processes that degrade H2O2-peroxidases through the suppression of metabolism, and catalases through direct enzyme damage. Cell killing was enhanced when water was replaced with D2O, suggesting that singlet oxygen plays a role, possibly as a precursor to H2O2 and/or as the mediator of catalase damage. UVA was especially toxic to mutants lacking miniferritin (dps) or recombinational DNA repair (recA) enzymes, indicating that reactions between ferrous iron and UVA-generated H2O2 lead to lethal DNA damage. Importantly, experiments showed that the intracellular accumulation of H2O2 alone is insufficient to kill cells; therefore, UVA must do something more to enable death. A possibility is that UVA stimulates the reduction of intracellular ferric iron to its ferrous form, either by stimulating O2•- formation or by generating photoexcited electron donors. These observations and methods open the door to follow-up experiments that can probe the mechanisms of H2O2 formation, catalase inactivation, and iron reduction. Of immediate utility, the data highlight the intracellular pathways formed under UVA light during SODIS, and that the presence of micromolar iron accelerates the rate at which radiation disinfects water.

Comparative photo-oxidative degradation of etodolac, febuxostat and imatinib mesylate by UV-C/H2O2 and UV-C/S2O82- processes: Modeling, treatment optimization and biodegradability enhancement.

The pharmaceutical contamination in aquatic environment has arisen increasing concern due to its potentially chronic toxicity. In recent years, HO° and SO4°- based advanced oxidation processes (AOPs) have been widely applied in water and wastewater treatments due to their highly efficiency on contaminant removal. Here, the response surface modeling (RSM) was used to investigate the degradation of three typical pharmaceuticals (i.e., etodolac (ETD), febuxostat (FBU) and imatinib mesylate (IMT)) by UV/H2O2 and UV/S2O82- processes. Based on the multiple regression analysis on full factorial design matrix and calculated reaction rate constants, the RSM was built. The experimental rate constants under optimal conditions were quite close to those obtained from the model, implying the good fit of the RSM. In addition, the RSM results indicated that UV/S2O82- process was less sensitive to pH in comparison to the UV/H2O2 process on target contaminant removal. Finally, it showed that UV/S2O82- process was superior to the UV/H2O2 process to on the enhancement of target contaminant biodegradability.

Decrypting the synergistic action of the Fenton process and biochar addition for sustainable remediation of real technogenic soil from PAHs and heavy metals.

The objective of this study was to demonstrate the feasibility and the relevance of combining biochar with the Fenton process for the simultaneous improvement of polycyclic aromatic hydrocarbons (PAHs) degradation and immobilization of heavy metals (HMs) in real soil remediation processes at circumneutral pH. The evaluation of PAHs degradation results was performed through multivariate statistical tools, including principal component analysis (PCA) and partial least squares (PLS). PCA showed that the level of biochar amendment decisively affected the degree of degradation of total PAHs, highlighting the role of biochar in catalyzing the Fenton reaction. Moreover, the PLS model was used to interpret the important features of each PAH's physico-chemical properties and its correlation to degradation efficiency. The electron affinity of PAHs correlated positively with the degradation efficiency only if the level of biochar amendment sat at 5%, explained by the ability of biochar to transfer the electrons to PAHs, improving the Fenton-like degradation. Moreover, the addition of biochar reduced the mobilization of HMs by their fixation on their surface, reducing the Fenton-induced metal leaching from the destruction of metal-organic complexes. In overall, these results on the high immobilization rate of HMs accompanied with additional moderate PAHs degradation highlighted the advantages of using a biochar-assisted Fenton-like reaction for sustainable remediation of technogenic soil.

Monitoring Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) Levels in Mixed-Use Residential-Commercial Buildings in Shiraz, Iran: Assessing the Carcinogenicity and Non-Carcinogenicity Risk of Their Inhabitants.

The aim of this study is to investigate the concentration of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) compounds in the indoor air of residential-commercial complexes and to compare it with other residential buildings (control) as well as to assess the carcinogenicity and non-carcinogenicity risk of these pollutants. BTEX concentration was investigated in the indoor air of 30 ground floor restaurants, 30 upper residential units of the complexes, 20 adjacent residential units (control), and their corridors. The mean BTEX concentration measured in the upper residential units was reported higher than in the control residential units, though they were not significantly different. The lifetime cancer risk (LTCR) value calculated for benzene in the upper residential units was lower than 10-4 and higher than 10-6 across all ages, indicating a carcinogenicity risk. Furthermore, the mean hazard quotient (HQ) for all compounds was obtained lower than 1, suggesting no concern about the non-carcinogenicity risk of these compounds in the studied region. Nevertheless, considering the sources of benzene production in the indoor air as well as the carcinogenicity of these pollutants and the risk they pose in human health, application towards the reduction of the sources and concentration of benzene in the indoor air are necessary.

Vacuum UV pre-treatment coupled with self-generated peroxide stimulation of biomass: An innovative hybrid system for detoxification and mineralization of toxic compounds.

The degradation of p-nitrophenol (pNP) was investigated in the chemical-less UVC/VUV process (Advanced Oxidation/Reduction Process, AORP), the packed bed bioreactor (PBR), and the hybrid of AORP/PBR system. The control UVC/VUV process degraded and mineralized pNP with rate constants of 0.098 and 0.032 min-1, respectively, at neutral initial pH. Operating the UVC/VUV process in a fluidized bed reactor improved the rate of pNP degradation by 21 % at a packing ratio of 0.5 %. The fluidized bed AORP was operated under continuous-flow mode, where 79 % degradation and 28 % mineralization of pNP were obtained along a significant improvement in the biodegradability (41 %) at a hydraulic retention time of 20 min. The oxidation with HO and reduction with eaq- simultaneously contributed to the degradation of pNP in the UVC/VUV process. In comparison, degradation and mineralization of pNP in a single PBR process (without pretreatment) was found to be 84.7 % and 47.2 %, respectively, during 30 h biotreatment. Coupling the fluidized bed UVC/VUV with the PBR attained complete biodegradation of the residual pNP within 1 h and over 89 % of TOC reduction during 3 h post treatment in the PBR. Accordingly, the hybrid, fluidized bed UVC/VUV reactor coupled with the PBR is an efficient and promising technology for treating toxic environmental contaminants.