Adsorption of As(V) at Humic Acid-Kaolinite-Bacteria Interfaces: Kinetics, Thermodynamics, and Mechanisms

The immobilization and transformation of arsenic at the mineral-organic interface in soil environments ultimately depend on components their interactions. Herein, effect humic acid (HA) a typical bacterium (a Gram-positive Bacillus subtilis) coating adsorption arsenate As(V) to kaolinite (Kao) mineral was investigated. reaction kinetics, isotherms, thermodynamics, mechanism clay composites kaolinite-Bacillus subtilis (Kao-B.s) acid-kaolinite-Bacillus (Kao-HA-B.s) were better fitted pseudo-second-order kinetics Freundlich model. capacity followed order Kao-HA-B.s > Kao-B.s B.s Kao-HA Kao. positive ΔH (31.44, 5.87 kJ mol−1) ΔG (0.10–0.96 values confirmed that by all nonspontaneous endothermic character room temperature. FT-IR, XRD, thermodynamic results revealed kaolinite–organic interfaces could be attributed electrostatic forces between terminal aluminum or silanol groups complexation HA, bacteria, As(V), which formed an inner-sphere complex surface complex, respectively. experimental showed Kao-bacteria system accompanied significant additive interactions, while ternary Kao-HA-bacteria had inhibitory binding higher HA content due shielding effect, with promotion shown lower concentration for dispersion particles.