An insight into the adsorption of three emerging pharmaceutical contaminants on multifunctional carbonous adsorbent: Mechanisms, modelling and metal coadsorption

Pharmaceuticals (PhCs) are a specific group of emerging environmental contaminants, because there are designed to influence biochemical processes in non-target organisms even at low concentrations. In this study, phosphorised carbonaceous adsorbent (CScPA) was prepared from lignocellulosic biomass through thermochemical functionalisation. Phosphorus (P) doped microparticles were evaluated for the removal of emerging pharmaceutical contaminants such as sulfamethoxazole (SMX), carbamazepine (CBZ) and ketoprofen (KP) from aqueous solution. Characterisation of the adsorbent with the detailed mechanism study was carried out using pHpzc, SEM, BET, FTIR and XRD instruments. The influence of initial pH, adsorbent dose, contact time, initial pharmaceutical concentration and temperature on adsorption efficiency and capacity was evaluated in batch studies. CScPA exhibited excellent removal efficiency (≈99%) for all tested pharmaceuticals. According to FTIR results, the P containing groups showed obvious positive effects on pharmaceutical removal. The Langmuir isotherm (with maximal adsorption capacity of 19.181, 21.895 and 19.675 mg/g for SMX, CBZ, and KP, respectively) and the pseudo second-order kinetic model were suitable for describing the adsorption process. Adsorption mechanisms were mainly governed by π-π and n-π EDA interactions and H-bonds. It was demonstrated that presence of metal ions did not significantly influence pharmaceutical removal.