Enhanced selective adsorption capacity of lead (II) from complex wastewater by aminopropyltriethoxysilane-functionalized biochar grafted on the MXene based on anion-synergism

The simultaneous elimination of dyes and metal ions from wastewater is essential for industrial wastewater treatment. In the current work, a novel adsorbent, aminopropyltriethoxysilane-functionalized biochar grafted on MXene (APTES/BC/MXene composite), was synthesized and utilized to increase the selectivity of the uptake of lead from a complex multi-metal solution based on anion-synergism. The surface area of the APTES/BC/MXene composite (164 m2/g) was higher as compared to the BC (90 m2/g), APTES (87 m2/g), and APTES/BC (151 m2/g). The outcomes of selective adsorption of metal ions were altered by the composite before (APTES = 52.98 mg/g, APTES/MXene = 58.65 mg/g, and APTES/BC = 313.86 mg/g) and after grafting aminopropyltriethoxysilane-functionalized biochar on the MXene (APTES/BC/MXene = 323.17 mg/g). In this investigation, the composite showed remarkable selectivity for the adsorption of lead. The adsorption capacity of composite for Pb2+ (323.17 mg/g) was superior compared to Cd (16.45 mg/g), Sr (10.99 mg/g), Zn (25.37 mg/g), Ni (7.82 mg/g, Ca (20.79 mg/g), and Ag (58.47 mg/g). Interestingly, the selective uptake of lead by the composite was enhanced from 446.85 to 1072.04 mg/g as coexisting methyl blue dosages increased from 0 to 100 mg/L at a pH value of 6.0. In the lead-methyl blue complex binary system, lead and methyl blue indicated synergistic phenomena, in which the existence of methyl molecules generated new unique sites for lead adsorption, while methyl blue uptake was also increased by the existence of lead. The experiment's findings demonstrate that the prepared APTES/BC/MXene exhibited excellent stability and regeneration capabilities (96.2% and 95.1% adsorption efficacy after 5th cycles for Pb2+ and MB respectively), suggesting it can be employed as a quick and efficient uptake adsorbent for the elimination of MB and Pb2+ in a single pollutant system. Hydrogen bonding, electrostatic interaction, synergistic penetration, and ion exchange processes were primarily involved in the uptake of lead and methyl blue. This investigation offers useful insights for the development of composite that indicate outstanding performance and easy recovery for the synergistic and simultaneous uptake of heavy metal ions and organic dyes. The results also reveal the remarkable enhancement of selective heavy metal uptake from complex wastewater by utilizing anion-bye interactions.