Preparation of macroscopic spherical porous carbons@carboxymethylcellulose sodium gel beads and application for removal of tetracycline

Abstract

The development of practicable and retrievable adsorbents with high adsorption capacity is a technical imperative for water treatment. Herein, we reported a new convenient macroscopic granular adsorbent for the removal of tetracycline (TC) from water by immobilizing porous carbons (PCs) which were obtained via one-step in situ pyrolysis from ethylenediaminetetraacetic acid dipotassium salt dihydrate (EDTA-2K·2H₂O) into carboxymethylcellulose sodium (CMCS) gel beads utilising molecular cross-linking. A remarkable similarity can be observed between multivariant gel beads and EDTA-2K·2H₂O derived porous carbons (EPCs) according to the characterization results. The adsorption performance was evaluated using batch adsorption studies of TC in aqueous solution: the kinetic results could be fit well by a pseudo-second-order model and intraparticle diffusion was treated as the rate-controlling step; equilibrium adsorption data fitted well to the Langmuir adsorption isotherm yielding a maximum adsorption capacity of 136.9 mg g⁻¹ at 298 K. Importantly, these results indicate that the as-prepared gel beads could be used as facile adsorbents in pharmaceutical wastewater treatment.