Removal of amoxicillin in aqueous phase by a sulfonic-phosphoricacid containing sorbent based on cation exchange mechanism

In order to study the effective removal method of residual penicillin antibiotics in water, amoxicillin (AMX) was taken as the research object. Firstly, the adsorption effect of different resins on AMX under acidic conditions was investigated, and the best resin was selected. Then, the best resin with sulfonic acid/phosphoric acid bifunctional MTS9570 was used as the adsorbent to further study its adsorption behavior of AMX. The adsorption kinetics studies show that the pseudo-second-order and intra-particle diffusion models can better describe the adsorption process of AMX on MTS9570, indicating that the adsorption process of AMX on MTS9570 is controlled by chemisorption and intra-particle diffusion, and the optimal adsorption capacity is 99.28 mg/g. According to the adsorption isotherm, Langmuir isotherm has the highest fitness, indicating that there is a single layer adsorption mechanism on the surface of MTS9570 adsorbent. Thermodynamic parameter ΔH < 0, ΔS > 0 and ΔG < 0, indicating that the adsorption at the solid-liquid interface is a spontaneous exothermic process with increased randomness. Combined with the above results and the structural properties of adsorbent and adsorbates, it is speculated that the adsorption of AMX by MTS9570 may be mainly controlled by electrostatic interaction and hydrogen bonding. After six sorption-desorption cycles, the adsorption capacity of MTS9570 can still reach 77.99% of the initial adsorption capacity, indicating that the adsorbent has good reusability.