Synthesis of Na-A zeolite from water treatment residue using hydrothermal and microwave techniques

摘要

Na-A zeolite was synthesized from water treatment residue(WTR)using hydrothermal and microwave techniques.WTR was brought from Metropolitan Waterworks Authority(Thailand)and was activated by firing at 700 °C for 3 h in an electric furnace.The activated WTR was reacted with 3 M NaOH solution in a reactor under a controlled temperature of 80,90 and 100 °C for 8,10,12,and 14 h.SEM(Scanning electron microscopy)images reveal the cubic crystal of zeolite.The highest cation exchange capacity(CEC)was obtained from sample synthesized at 90 °C for 14 h and gave the CEC value of 3.14 meq/g Ca~(2+).For the microwave technique,the raw materials were reacted at 80 90 and 100°C for 30,60,and 120 min.Results showed that the sample obtained at 80 °C for 30 min represented the highest CEC value of 0.29 meq/g Ca~(2+).