Preparation of amino-modified SiO2 and its adsorption properties of dyes
Amino-modified SiO2(SiO2-PL)was prepared by grafting KH-550 followed by cross-linking ε-PL with SiO2,KH-550,and ε-PL as raw materials and glutaraldehyde as a cross-linking agent.The adsorption properties of SiO2-PL on dye pollutants were investigated by using Congo red(CR)and methylene blue(MB)as the target pollutants.According to the results of SEM characterization,SiO2-PL has an abundant and clear pore structure.The experimental results show that SiO2-PL adsorbs up to 377.06 mg/g of CR and 73.01 mg/g of MB under the conditions of adsorption temperature of 25℃,solution pH 7,initial CR mass concentration of 1 000 mg/L,or initial MB mass concentration of 300 mg/L,and adsorption time of 110 min;the adsorption process of CR and MB by SiO2-PL is in accordance with the quasi-secondary kinetic model,and with the isothermal adsorption models of Freundlich and Langmuir,respectively;in the binary adsorption system,the adsorption amount of CR by SiO2-PL is smaller than that of its single system,while the adsorption amount of MB is larger than that of its single system;the first-time adsorption rates of CR and MB by SiO2-PL are up to 97.83%and 91.73%,respectively,and after 4 adsorption-desorption cycles,the adsorption rate can still reach 80.42%and 78.28%.
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