Selective, highly efficient extraction of Cr(III), Pb(II) and Fe(III) from complex water environment with a tea residue derived porous gel adsorbent

Abstract

A novel macroporous (~150 μm) double network hydrogel (TR/PAA) was prepared from tea residue and acrylic acid, and its performance was systematically evaluated. The static adsorption experiments showed that gel exhibited high selectivity and adsorption capacity, ultrafast kinetics (~10 min) for Cr(III), Pb(II) and Fe(III). The adsorption behavior showed heterogeneous and chemisorption process adsorption capacities of 206.19, 253.16, and 94.88 mg g^-1 for Cr(III), Pb(II) and Fe(III), respectively. In pluralistic systems, TR/PAA showed the adsorption order of Fe(III) > Cr(III) > Pb(II). Mechanism studies confirm that nitrogen and oxygen-containing functional groups play a major role in the adsorption process. In the fixed-bed column experiments, the treatment volume of simulated wastewater reached 1400 bed volumes (BV) (21.6 L), producing only 7 BV (323 mL) eluent. This work provides a new avenue for the combination of TR/PAA reuse and heavy metal removal, which is expected to be applied in actual wastewater treatment.

Keywords: Adsorption Mechanism; Fixed-Bed Column; Hydrogel; Tea Residue.