Sustainable Cu2(OH)2CO3/g-C3N4/cellulose acetate-derived porous composite membrane for Congo red and tetracycline removal with photocatalytic self-cleaning properties under natural solar irradiation

Abstract

A highly efficient and sustainable Cu/CN@CA composite membrane was synthesized for the removal of typical dyes and antibiotics by incorporating a Cu₂(OH)₂CO₃/g-C₃N₄ heterojunction (Cu/CN) onto a cellulose acetate (CA) membrane. The 0.2Cu/CN@CA membrane with optimized Cu/CN doping achieved superior Congo red (CR) and tetracycline (TC) adsorption capacities of 250.8 and 48.43 mg/g, respectively. Notably, the exhausted 0.2Cu/CN@CA after adsorption saturation could be effectively self-cleaned under natural solar irradiation. Consecutive adsorption-photocatalytic experiments revealed its fine stability and recyclability. Mechanistic exploration based on experimental analysis and DFT (Density Function Theory) calculations revealed that cellulose acetate accommodates the charge transfer interactions between g-C₃N₄ and Cu₂(OH)₂CO₃, wherein many photogenerated electrons were generated and migrated from g-C₃N₄ to Cu₂(OH)₂CO₃. This type II heterojunction transfer pathway induced the strong oxidizability of the 0.2Cu/CN@CA membrane with plenty of active species for the photocatalytic degradation of the adsorbed CR and TC contaminants under solar light irritation. This study provided a novel sustainable membrane-based adsorbent for the enhanced dye and antibiotic contaminant remediation of aquatic environments.