Efficient capture of aqueous humic acid using a functionalized stereoscopic porous activated carbon based on poly(acrylic acid)/food-waste hydrogel.

Stereoscopic porous carbons have shown good potential in humic acid (HA) removal. In this work, a novel stereoscopic porous activated carbon (SPAC) was designed and synthesized via the self-assembly of a hydrogel based on food waste during in-situ polymerization, vacuum drying, carbonization, and activation. Then, the SPAC was functionalized with 3-aminopropyltriethoxysilane (APTES) and the adsorption behavior of the modified SPAC (SPAC-NH2) was studied systematically. The effects of pH, contact time, initial concentration of HA, and adsorbent dose were investigated, showing that optimal HA removal efficiency (>98.0%) could be achieved at an initial HA concentration of 100 mg/L. The experimental adsorption isotherm data was fitted to the Langmuir model with a maximum adsorption capacity of 156.0 mg HA/g SPAC-NH2. Analysis of the mechanism indicated that the removal of HA was mainly realized through the amidization reaction between the COOH groups of HA and the NH2 groups of APTES. All of the above results showed that SPAC-NH2 powder is an efficient, eco-friendly, and reusable adsorbent which is suitable for the removal of HA from wastewater.