Adsorption characteristics of lead(II) ions onto the clay/poly(methoxyethyl)acrylamide (PMEA) composite from aqueous solutions

摘要

The presence of heavy metals in the aquatic environment has been a big deal to scientists due to their increased discharge,toxic nature,and other adverse effects on receiving waters.Even a very low concentration of lead in water is very toxic to aquatic life.The main sources of lead in water are the effluents of processing industries.Due to the fact that lead poisoning in human causes severe damage to the kidney,nervous system,reproductive system,liver,and brain causes sickness or death.The present research was aimed at the development of clay-based composite as an adsorbent that it can be used in the removal of lead(II) ions by adsorption to obtain equilibrium,kinetics and thermodynamic parameters.In this respect,the monomer,methoxyethylacrylamide (MEA) was synthesized by the nucleophilic substitution reaction of acryloyl chloride with methoxyethylamine.After that clay-poly(methoxyethyl)acrylamide (PMEA) composite was obtained by the bulk polymerization method at +4°C by using N,N-methylenebisacrylamide (MBA) as crosslinker,potassium persulfate (KPS) and tetramethylethylenediamine (TEMED) as the initiator and accelerator,respectively.The surface characterization of both clay and clay-based composite was performed by using the FTIR technique.The experimental results show that the equilibrium contact time was obtained within 60 min and the maximum adsorption capacity was 3.91 x 10~(-1) mol g~(-1) or 81.02 mg g~(-1).The dynamic data fitted to the pseudo-second-order kinetic model well.The Langmuir isotherm model agrees well with the equilibrium experimental data.The thermodynamic parameters were also deduced for the adsorption of lead(II) ions into clay-based composite and the results show that the adsorption was spontaneous and endothermic.