Simultaneous Adsorption Of Diclofenac And Phosphorus In Reclaimed Water Using Polypyrrole Modified Red Mud

The main pollutants in reclaimed water is phosphorus,nitrogen,heavy metals and large quantities of refractory trace organic pollutants,etc.Diclofenac（DCF）is one of the most frequently detected pollutants in surface water and municipal wastewater.The environmental risk assessment indicates DCF is of high environmental risk and greater environmental hazard than other Pharmaceutical and Personal Care Products（PPCPs）.Phosphorus（P）is the important control index in reclaimed water reusing as scenic water.In that,the concentration control of both DCF and P is of great significance in safe utilization of reclaimed water.This study investigated the feasibility of simultaneous adsorption of DCF and P.Polypyrrole modified red mud composite was synthesized by FeCl₃ oxidation method to remove DCF and P in solution simultaneously and efficiently.The synthesis conditions of polypyrrole modified red mud were investigated.It showed that the mass ratio among the monomer,the red mud and FeCl₃ 0.6:1:1 was more efficient and cost effective to the synthesis of adsorbents for adsorptive removal of diclofenac and phosphorus,and the simultaneous removal rate were both higher than 98%when the initial concentration of diclofenac sodium（DS）and phosphate were both 10 mg/L.The characteristics of different synthesis materials were investigated according to SEM-EDS/Mapping,BET,XRD,FTIR and XPS analysis.It was found that the successful load of PPy on red mud and the coordination of lone pair electrons of N in PPy with Fe in RM was the main synthesis mechanism of the adsorbent.The effects of adsorbent dosage,initial p H value,adsorption time,initial concentration on the adsorption properties of the adsorbents were investigated.That the dosage of adsorbent 1.0 g/L,the initial p H 5.0 and the adsorption time 2 h was more efficient and cost effective to the adsorption under experiment conditions.The experimental data were better fitted with the the pseudo-second order kinetic and Freundlich isotherm models.The adsorption efficiency of adsorbent on the secondary effluent of wastewater treatment plant were investigated.It was found that the adsorbent has a certain removal effect on phosphorus and trace organic pollutants including diclofenac,sulpiride,metoprolol,roxithromycin removal in secondary effluent,and the removing rate was at the range of 19.6%-66.7%.The adsorption mechanisms and simultaneous adsorption relation of DS and P on polypyrrole modified red mud were studied.The simultaneous adsorption of DS and P presented competitive relation to effective adsorption sites.The measured maximum equilibrium adsorption capacity of DS and P were 210.23 mg/g and 28.57 mg/g.The adsorption mechanisms were mainly related to ion exchange of Cl^-and electrostatic attraction with DS and P,and chemical precipitation only occurred in P adsorption by ligand exchange between phosphate and-OH in PPy/RM.