Enhanced Adsorption of Humic Acid on Amino-Modified Bentonite

Humic acid (HA) can cause environmental pollution, due to which, its removal from aqueous solutions has become an increasingly important issue. Although bentonite has an affinity for HA, the adsorption capacity of raw bentonite is still poor. As a commonly used organic modifier, 3-aminopropyltriethoxyorganosilane (APTES) exhibits excellent flocculation capability for HA. Therefore, the objective of the present study was to investigate the effectiveness of the addition of 3-aminopropyltriethoxyorganosilane (APTES) to raw bentonite to increase the adsorption of HA from aqueous solution. The experimental results showed that, when the solid-to-liquid ratio was 1:1, the amino-modified bentonite exhibited the highest adsorption capacity (qmax = 272.23 mg g-1). The adsorption affinity of amino-modified bentonite was mainly determined by the number of amino groups loaded onto its surface. The adsorption of HA on amino-modified bentonite occurred through electrostatic interactions and hydrogen bonding. These findings demonstrate the excellent potential of amino-modified bentonite in effectively remediating HA pollution.