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In this study, FeS 2 @SiO 2 microspheres were firstly employed as a heterogeneous catalyst to activate persulfate (PS) for the degradation of bisphenol A (BPA) from aqueous solutions. The most relevant findings revealed that UV irradiation induced a significant improvement in the degradation of BPA by the FeS 2 @SiO 2 microspheres/PS system. Nearly 100% of BPA degradation by the FeS 2 @SiO 2 microspheres/PS/UV system was achieved within 120 min at reaction conditions of 1 mM PS, 0.066 mM BPA, 1.0 g/L FeS 2 @SiO 2 microspheres and pH 3.0. A high performance on the degradation of BPA might be attributable to a synergistic effect between the PS/UV and the FeS 2 @SiO 2 microspheres/PS catalytic processes. It was found that the BPA degradation could be inhibited by the coexisting anions like Cl − , HCO 3 − and PO 4 3− to different extents at much higher concentrations, whereas NO 3 − had a negligible effect. Organic acids such as ethylene diamine tetra-acetic acid (EDTA) and oxalic acid (OA) would lead to an enhancement with a lower dosage, whereas a significantly negative effect was observed at much higher dosages. Radical scavenging tests revealed that the SO 4 − radicals prevailed over HO . A total of seven intermediates during the degradation of BPA were identified by GC/MS, and a possible reaction pathway and mechanism of BPA degradation by the FeS 2 @SiO 2 microspheres/PS/UV system was proposed. This study demonstrated a simple water treatment method involving the use of low cost natural iron minerals for organic pollutants removal. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 60 min 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. [ABSTRACT FROM AUTHOR]

In this study, bentonite-supported nanoscale zero-valent iron (B-nZVI) was used as a catalyst to activate persulfate (PS) for the simultaneous removal of Cr(VI) and phenol from aqueous solutions. Experimental results indicated that the presence of bentonite could decrease the aggregation of nZVI and increase its reactivity. The removal rates of Cr(VI) and phenol by B-nZVI system were 99.90% and 6.50%, respectively. Whereas the corresponding values by B-nZVI/PS system were 99.30% and 71.50%, respectively. The presence of persulfate could not significantly decline B-nZVI reactivity toward Cr(VI) reduction but remarkably promote phenol oxidation. The addition of Cr(VI) did positively affect the oxidation rate of phenol, a significant synergistic effect between Cr(VI) reduction and phenol oxidation was achieved in B-nZVI/PS system. A positive correlation between persulfate decomposition and dissolved Fe 2+ was found. Cr(III) species such as Cr 2 O 3 , Cr(OH) 3 were identified in Cr(VI) reduction process, whereas the oxidation products such as catechol, 1,4-benzoquinone, propionic acid and formic acid were identified in phenol oxidation process. The reusability experiments of B-nZVI demonstrated that the structure of B-nZVI was relatively stable after four cycles of reuse. This is the first report for the feasibility of B-nZVI as a catalyst to activate persulfate for the simultaneous removal of heavy metal and organic pollutant. [ABSTRACT FROM AUTHOR]

Nowadays, a great increasing attention has been paid to the coexistence of multiple inorganic pollutants in the environment. In this study, a novel crayfish shell biochar-Fe composite (FXB) was successfully produced and effectively used for the synchronous removal of Cr(VI) and phosphates (P) from aqueous solution. Experimental results revealed that FXB exhibited a high performance on the removal of Cr(VI) and P over a broader pH range. The escalating ionic strength and anions like Cl- and NO 3 - showed varying degrees of inhibition effects on Cr(VI) and P removal. The kinetic model of both Cr(VI) and P adsorption fit better with the pseudo-second-order model compared with the pseudo-first-order model. The isotherm of Cr(VI) fit well with the Langmuir model, whereas that of P adsorption fit well with the Freundlich model. Elovich model suggests that both Cr(VI) and P adsorption were the heterogeneous and multi-mechanism processes, and the intra-particle diffusion model confirms that these adsorption processes were dominated by surface and intra-particle diffusion reactions. Both Cr(VI) and P adsorption onto FXB were the spontaneous and endothermic nature. The synchronous removal of Cr(VI) and P could be efficiently achieved using this FXB composite under the certain conditions. A possible reaction mechanism for the synchronous adsorption of Cr(VI) and P onto FXB involving the synergistic effects of surface adsorption, precipitation, reduction and complexation processes was proposed. [Display omitted] • A novel crayfish shell biochar-Fe composite (FXB) was successfully obtained. • FXB exhibited the high Cr(VI) and P adsorption capacities at wide pH values. • Both Cr(VI) and P adsorption onto FXB were the spontaneous and endothermic nature. • The synchronous removal of Cr(VI) and P could be efficiently achieved with FXB. • The mechanism for the synchronous adsorption of Cr(VI) and P was proposed. [ABSTRACT FROM AUTHOR]

Nowadays, nanoscale zero valent iron (nZVI) has been extensively applied for the decontamination of various pollutants, but passivation of nZVI severely affects its reactivity in use. In this study, ultrasound (US)-assisted catalytic reduction of Cr(VI) by an acid mine drainage based nZVI (AMD-nZVI) coupling with FeS 2 system was systematically examined. Results show that the presence of FeS 2 and US induced a synergistic enhancement of Cr(VI) removal by AMD-nZVI. Nearly 98% of Cr(VI) removal was achieved by AMD-nZVI/FeS 2 /US process within 60 min under optimal reaction conditions. Several coexisting substances with lower concentration including Pb(II), Ni(II), bisphenol A (BPA) and 2,4-diclorophenol (2,4-DCP) could be effectively removed in simultaneous manner with Cr(VI) removal. The inhibitory order of water matrix species on Cr(VI) removal was NO 3 − > PO 4 3− > HCO 3 − > Ca2+ > Mg2+ > Cl−, and a serious suppression effect was induced by humic acid (HA). Addition of ethylene diamine tetra-acetic acid (EDTA) and citric acid (CA) could enhance Cr(VI) removal rate. An enhanced reaction mechanism was proposed, which involved the regeneration of more Fe2+ and H+ by AMD-nZVI/FeS 2 /US process, leading to the reduction of Cr(VI) by AMD-nZVI and FeS 2 into Cr(III) species inculding Cr 2 O 3 and Cr(OH) 3. This study well demonstrates that AMD-nZVI/FeS 2 /US process is considered as a potential candidate for the remediation of Cr(VI) in real wasterwater. Image 1 • FeS 2 induced an enhanced removal of Cr(VI) by AMD-nZVI/US process. • The formation of Fe2+ and acidic condition played a primary role in this process. • Removal of Pb(II), Ni(II), 2,4-DCP and BPA could be achieved with Cr(VI) removal. • Most of Cr(VI) species was sucessfully reduced into Cr 2 O 3 and Cr(OH) 3. • Enhanced mechanism of Cr(VI) removal by AMD-nZVI/FeS 2 /US process was proposed. [ABSTRACT FROM AUTHOR]