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[Display omitted] • A new biochar-based magnesium oxide composite (MTBC) was firstly prepared. • TDF adsorption was well described by pseudo-second-order and Langmuir models. • Chemical adsorption process was dominant in TDF adsorption over MTBC. • Simultaneous removals of TDF and DIN has been achieved by MTBC. • A reaction mechanism of TDF and DIN adsorption by MTBC was proposed. In recent years, the ecological security has been seriously threatened by the residues of pesticides in the environment. In this study, a new biochar-based magnesium oxide composite (MTBC) was successfully prepared using Traditional Chinese Medicine residues and MgCl 2 solution, and then applied for the removal of triadimefon (TDF) and/or dinotefuran (DIN) in water. Batch experiments results indicated that 86.42 and 87.86 % of TDF and DIN removals could be obtained by MTBC within 120 min, respectively. The TDF adsorption process was proved to be well fitted with the pseudo-second-order kinetic, Elovich, liquid film diffusion, Intra-particle diffusion and Langmuir isothermal models. The TDF adsorption by MTBC was a spontaneous endothermic reaction, and chemical adsorption process was dominant. The inhibitory of the coexisting anions on TDF removal followed the order of SO 4 2−＜Cl−＜HPO 4 3−＜HCO 3 –. Both TDF and DIN could be simultaneously removed by MTBC at the certain concentrations levels. The possible removal mechanism for the adsorption of TDF and DIN by MTBC was proposed, both TDF and DIN were rapidly distributed and adsorbed on MTBC surface, then diffused into the interior pores structure and were finally adsorbed on MTBC through various reaction processes. The TDF removal process might be involved with hydrogen bonding, π-π interaction, pore filling and electrostatic interaction, while DIN removal might be involved with hydrogen bonding, pore filling and electrostatic interaction. These findings suggested that biochar-based magnesium oxide composite was an effective adsorbent for the remediation of agricultural effluents containing TDF and DIN. [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]