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[Display omitted] • Oxalic acid (OA) maintain a high dissolved Fe2+ in the PC-ZVI/PMS process. • Peroxymonosulfate (PMS) greatly improve atrazine (AE) removal. • The contribution order of reactive species followed as HO• > SO 4 •- greater than1O 2 > O 2 •−. • The possible degradation pathways of AE by PC-ZVI/PMS/OA process proposed. • Enhanced mechanism of Cr6+ and AE removal by PC-ZVI/PMS/OA process was proposed. Nowadays, clean-up of heavy metals and pesticides from environment has received great attention. A green biochar iron composite (PC-ZVI) was successfully synthesized using pomelo peel residues and FeCl 3 solution. Peroxymonosulfate (PMS) was introduced into the PC-ZVI system for Cr(VI) and atrazine (AE) removal, and results showed that PMS greatly promoted Cr(VI) and AE removal. The presence of oxalic acid (OA) could maintain a relatively high dissolved Fe2+ species for Cr(VI) reduction and AE oxidation in the PC-ZVI/PMS process. The contribution order of reactive oxygen species followed as HO• > SO 4 •- greater than1O 2 > O 2 •− in both Cr(VI) and AE removal by PC-ZVI/PMS/OA process. A total of six intermediates products of AE degradation were detected, and AE molecular was effectively degraded into CO 2 , H 2 O, inorganic N and Cl through hydroxylation, substitution and de-alkylation processes. The underlying mechanism of Cr(VI) and AE removal by PC-ZVI/PMS/OA process was also proposed. Most Cr(VI) species were transformed into Cr 2 O 3 and Cr(OH) 3 through reduction and precipitation processes. PC-ZVI has a relatively high recyclability toward both Cr(VI) and AE removal from solutions. The potential toxicity of PC-ZVI solution was small at three PC-ZVI dosages levels, and the corresponding toxicity of AE reaction solution by PC-ZVI/PMS/OA process decreased as reaction time increased. The order of both Cr(VI) and AE removal in different water systems was tap water > river water > lake water > wastewater, and this PC-ZVI/PMS/OA process exhibited the better adaptability in application for several actual water environments. [ABSTRACT FROM AUTHOR]

Nowadays, the residual heavy metals and antibiotics in water and soil have a potential threat to human being health, thereby their purification is of great importance. In this study, the application of Cr6+ and chlortetracycline (CTC) removal using a new fruit peel based biochar composite (FPBC) had been explored. Batch experiments results showed that FPBC presented excellent removal performance on Cr6+ and CTC, and the simultaneous removal efficiencies of Cr6+ and CTC were 97% and 81% within 180 min, respectively. The adsorption kinetics and isotherms of Cr6+ by FPBC could be well described by the pseudo-second-order and Langmuir models, respectively, and its adsorption was a spontaneous endothermic process. The inhibitory of the coexisting anions on Cr6+ removal of followed the order of HPO 4 3-> HCO 3 -> SO 4 2->NO 3 -> Cl-. The simultaneous removal of Cr6+ and CTC by FPBC had been achieved at low CTC content levels. The presence of NaCl showed a significant inhibitory on Cr6+ removal but a positive effect on CTC removal at low content level. A potential reaction mechanism of both Cr6+ and CTC removal over FPBC was proposed on the basic of the comprehensive characterizations and adsorption performance. Both reduction and surface precipitation reactions might be dominant in Cr6+ removal process, whereas both complexation and hydrogen bond interaction might be mainly responsible for CTC removal. These findings suggested that this fruit peel based biochar composite might be a promising material for the remediation of Cr6+ and CTC-contaminated wastewater. [Display omitted] • A new fruit peel based biochar composite (FPBC) was firstly synthesized. • Cr6+ adsorption was well described by pseudo-second-order and Langmuir models. • NaCl showed an inhibitory on Cr6+ removal but a positive effect on CTC removal. • FPBC presented a high simultaneous removal of Cr6+ and CTC. • A potential mechanism for Cr6+ and CTC removal over FPBC was proposed. [ABSTRACT FROM AUTHOR]

Recently, a large number of agricultural wastes have been extensively converted into biochar based materials, these biochar materials have been popularly employed in the removal of various pollutants from environment. Herein, a novel pigeon waste based biochar composite (FeBC) was firstly synthesized and applied for hexavalent chromium (Cr(VI)) and p-nitrophenol (PNP) adsorption in water. The most relevant findings showed that FeBC exhibited a superior performance on Cr(VI) and PNP adsorption compared with pristine biochar. The Cr(VI) monolayer adsorption onto FeBC might be dominant, and Cr(VI) adsorption by FeBC was an endothermic process. Both Cr(VI) and PNP adsorption behavior were well fitted with the pseudo-second-order kinetic model, Elovich, intra-particle diffusion (IPD), liquid film diffusion kinetic (LFD) and chemical reaction models. Both the pathway of PNP degradation and mechanism for Cr(VI) and PNP adsorption over FeBC were proposed. Almost half of Cr(VI) was reduced into Cr 2 O 3 and Cr(OH) 3 , both reduction and precipitation reactions might be dominant in Cr(VI) adsorption. O 2 •−, 1 O 2 and •OH were involved in PNP removal reaction, but the contribution of •OH was small. The oxidation, π-π interaction and hydrogen bonds interactions might be involved in this PNP removal process, and PNP was oxidized to form several intermediates via hydroxylation and ring cleavage reactions. This study could provide a novel treatment strategy for the simultaneous decontamination of effluents combined with heavy metals and organic compounds in realistic remediation application. [Display omitted] • A novel pigeon waste based biochar composite (FeBC) was firstly synthesized. • Almost half of Cr(VI) species were reduced into Cr 2 O 3 and Cr(OH) 3. • O 2 •−, 1 O 2 and •OH were involved in p-nitrophenol removal reaction. • Both Cr(VI) and p-nitrophenol removal were successfully achieved by FeBC. • A mechanism for the removal of Cr(VI) and p-nitrophenol was proposed. [ABSTRACT FROM AUTHOR]