Search

Coexistence of organic compounds and heavy metals in aquaculture waters is a widespread problem. In this study, a rapid reduction of Cr(VI) and oxidation of ciprofloxacin (CIP) in a simultaneous manner was firstly reported through the photocatalysis of TiO 2 /Fe 0 composite under aerobic conditions. The significantly enhanced removals of Cr(VI) and CIP by TiO 2 /Fe 0 composite due to a synergetic effect between oxidation and reduction processes. Within 60 min UV light irradiation, the simultaneous removals of Cr(VI) and CIP by TiO 2 /Fe 0 composite were 97.7 and 94.6%, respectively, whereas the corresponding values by TiO 2 were 57.9 and 68.7%. CIP oxidation process could be significantly accelerated under acidic and aerobic conditions. Intriguingly, a low Pb(II) concentration could induce an enhancement of CIP oxidation, whereas a negative effect on both Cr(VI) reduction and CIP oxidation was observed at a relatively high concentration. A low concentration of ethylene diamine tetra-acetic acid (EDTA) did positively affect both Cr(VI) reduction and CIP oxidation processes, whereas a negative effect on CIP oxidation was found at a relatively high concentration. A possible reaction pathway and mechanism between CIP oxidation and Cr(VI) reduction was proposed. CIP was attacked by HO produced from the decomposition of water and photo-excited holes through substitution and hydroxylation processes, leading to the production of a series of intermediates, whereas the Cr(VI) was converted into Cr(III) through the capture of photo-excited electrons and Fe 0 reduction. [ABSTRACT FROM AUTHOR]

The interaction of warming and soil texture on responsiveness of the key soil processes i.e . organic carbon (C) fractions, soil microbes, extracellular enzymes and CO 2 emissions remains largely unknown. Global warming raises the relevant question of how different soil processes will respond in near future, and what will be the likely regulatory role of texture? To bridge this gap, this work applied the laboratory incubation method to investigate the effects of temperature changes (10-50 °C) on dynamics of labile, recalcitrant and stable C fractions, soil microbes, microbial biomass, activities of extracellular enzymes and CO 2 emissions in sandy and clayey textured soils. The role of texture (sandy and clayey) in the mitigation of temperature effect was also investigated. The results revealed that the temperature sensitivity of C fractions and extracellular enzymes was in the order recalcitrant C fractions > stable C fractions > labile C fractions and oxidative enzymes > hydrolytic enzymes. While temperature sensitivity of soil microbes and biomass was in the order bacteria > actinomycetes > fungi ≈ microbial biomass C (MBC) > microbial biomass N (MBN) > microbial biomass N (MBP). Conversely, the temperature effect and sensitivity of all key soil processes including CO 2 emissions were significantly ( P < 0.05) higher in sandy than clayey textured soil. Results confirmed that under the scenario of global warming and climate change, soils which are sandy in nature are more susceptible to temperature increase and prone to become the CO 2 -C sources. It was revealed that clayey texture played an important role in mitigating and easing off the undue temperature influence, hence, the sensitivity of key soil processes., Competing Interests: The authors declare that they have no competing interests., (© 2022 Hassan et al.)

In this study, bentonite-supported nZVI (B-nZVI) was used as a catalyst to activate H 2 O 2 for atrazine (ATZ) degradation in the presence of FeS 2 . Results indicated that ATZ degradation by B-nZVI/H 2 O 2 process was significantly enhanced when FeS 2 was introduced, and nearly 98% of ATZ was degraded by B-nZVI/FeS 2 /H 2 O 2 process within 60 min under the optimum conditions. ATZ degradation of B-nZVI/FeS 2 /H 2 O 2 process was much higher than the sum of B-nZVI and FeS 2 /H 2 O 2 processes. The presence of HCO 3 - , PO 4 3- and F - exhibited significant negative effects on the ATZ degradation, whereas both Cu 2+ and Ni 2+ exhibited positive effects on that. Both citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) with lower concentration enhanced ATZ degradation rate, but significant suppression effects on that with higher concentration. The degradation of ATZ and 2,4-Dichlorophenol (2,4-DCP) could be simultaneously achieved in B-nZVI/FeS 2 /H 2 O 2 process under certain conditions. High soluble Fe 2+ induced an excellent decomposition of H 2 O 2 by B-nZVI and FeS 2 . OH was dominant radical, and contributed to nearly 86% of the overall ATZ removal. A total of five intermediate products of ATZ were identified, and ATZ degradation was achieved via de-alkylation and hydroxylation processes. An enhanced reaction mechanism for ATZ degradation by B-nZVI/FeS 2 /H 2 O 2 process was proposed, and B-nZVI/FeS 2 /H 2 O 2 process exhibited an excellect catalytic performance within four successive runs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, the feasibility of a novel Ca-Ag 3 PO 4 composite with visible light irradiation for the phenanthrene (PHE) degradation and algae inactivation in artificial seawater was firstly investigated. The experimental findings revealed that Ag 3 PO 4 phase was sucessfully formed on the Ca-based material, and the presence of Ca-based material could effectively keep Ag 3 PO 4 particles stable. An excellent performance on PHE degradation or algae inactivation was observed from Ca-Ag 3 PO 4 composite under visible light irradiation. The degradation of PHE or inactivation of algae not only could be efficiently achieved in the single mode, but also could be successfully achieved in the coexisting mode. Above 96% of PHE and algae were simultaneously removed within 12 h in the Ca-Ag 3 PO 4 /visible light system. It was further observed that the degradation of PHE and/or inactivation of algae increased with the increase of Ca-Ag 3 PO 4 dosage. HO was the primary radical responsible for PHE degradation, whereas HO and Ag + released from Ca-Ag 3 PO 4 mainly contributed to the algae inactivation. A possible mechanism involving the catalytic removal of PHE and algae by Ca-Ag 3 PO 4 under visible light irradiation was proposed. This study provides helpful guide for the simultaneous removal of various pollutants in real seawater., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Cr 6+ and Pb 2+ are both highly toxic pollutants and commonly co-exist in some industrial effluents and contaminated waters. In this study, simultaneous removal of Cr 6+ and Pb 2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero-valent iron (SSB-nZVI) was systematically investigated. It was well demonstrated that a porous structure was successfully formed on the SSB-nZVI when the starch was used as an additive. A synergistic effect on the adsorption and reduction over the SSB-nZVI was achieved, resulting in nearly 90 and 82% of Cr 6+ and Pb 2+ removal within 30 min, respectively. Cr 6+ was reduced prior to Pb 2+ . A low pH could accelerate the corrosion of nZVI as well as phosphate leaching. When Malachite green was added as a coexisting organic pollutant, its effective removal was found due to the formation of a Fenton-like system. The SSB-nZVI could be run consecutively three times with a relatively satisfactory performance. Most of Cr 6+ was converted into Cr 2 O 3 and Cr(OH) 3 on the SSB-nZVI surface, whereas most of Pb 2+ species existed as Pb(OH) 2 (or PbO). A possible reaction mechanism on the SSB-nZVI involved the adsorption, reduction and precipitation of both Cr 6+ and Pb 2+ over the particles. Present study sheds light on the insight of the fate and transport of Cr 6+ and Pb 2+ in aquatic environment, as well provides helpful guide for the remediation of coexistence of pollutants in real applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, a novel biochar-supported zero valent iron (BC-nZVI) was synthesized through a green method. A high performance on the simultaneous removal of Cu 2+ and bisphenol A (BPA) by a combination of BC-nZVI with persulfate (BC-nZVI/PS) system was successfully achieved. The simultaneous efficiencies of Cu 2+ and BPA could reach 96 and 98% within 60 min, respectively. Both HO• and SO 4 •- were two major reactive species in BC-nZVI/PS system, and SO 4 •- was primary radical responsible for the degradation of BPA. Four kinds of Cu species, such as Cu(OH) 2 , CuO, Cu 2 O and Cu 0 were generated via the adsorption and reduction of the BC-nZVI, whereas six kinds of products of BPA including p-isopropenyl phenol and 4-isopropylphenol were generated via the combined oxidation of SO 4 •- and HO•. The possible reaction mechanism for the simultaneous removal of Cu 2+ and BPA by BC-nZVI/PS system contained a synergistic effect between the reduction of Cu 2+ and the oxidation of BPA. This is the first report on the feasibility of the remediation of coexistence of heavy metal and organic compound in aquatic environment using the BC-nZVI/PS system., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In this study, the application of FeS 2 /SiO 2 microspheres as a catalyst to activate H 2 O 2 for the degradation of ciprofloxacin (CIP) was systematically investigated. Results demonstrated that the presence of SiO 2 microspheres on the surface of FeS 2 could effectively make the reaction of aqueous Fe 2+ and H 2 O 2 smoothly continuous by controlling the release of aqueous Fe 2+ from FeS 2 . Nearly 100% of CIP was degraded after 60min under the optimum conditions. A superior performance on the CIP degradation and high reusability of the catalyst was obtained in FeS 2 /SiO 2 microspheres activated H 2 O 2 system. A low concentration of ethylene diamine tetraacetie acid (EDTA) did positively affect the degradation rate of CIP. A synergetic effect between adsorption and oxidation processes contributed to the significant enhancement of CIP degradation. Seven oxidation intermediates were identified during the CIP degradation process, and the direct HO oxidation proved to be a main CIP degradation pathway. For degradation pathway of CIP, oxidation of piperazine ring would be its first step, followed by cleavage of the heterocyclic ring. Subsequently, the substitution, hydroxylation and decarboxylation processes occurred. This is the first report on the feasibility of FeS 2 /SiO 2 microspheres activated H 2 O 2 system for the enhanced degradation of CIP., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A novel two-compartment photo-electro-chemical catalytic reactor was designed. The TiO2/Ti thin film electrode thermally formed was used as photo-anode, and graphite as cathode and a saturated calomel electrode (SCE) as the reference electrode in the reactor. The anode compartment and cathode compartment were connected with the ionic exchange membrane in this reactor. Effects of initial pH, initial concentration of malachite green and connective modes between the anode compartment and cathode compartment on the decolorization efficiency of malachite green were investigated. The degradation dynamics of malachite green was studied. Based on the change of UV-visible light spectrum, the degradation process of malachite green was discussed. The experimental results showed that, during the time of 120 min, the decolouring ratio of the malachite green was 97.7% when initial concentration of malachite green is 30 mg x L(-1) and initial pH is 3.0. The catalytic degradation of malachite green was a pseudo-first order reaction. In the degradation process of malachite green the azo bond cleavage and the conjugated system of malachite green were attacked by hydroxyl radical. Simultaneity, the aromatic ring was oxidized. Finally, malachite green was degraded into other small molecular compounds.