Adsorption Of Rhodamine B And Naphthalene From Water By Organic Modified Zeolites

As a kind of synthetic dyes,Rhodamine B is widely used in production of textiles, paper, leather and glass. Rhodamine B-contained wastewater with high chroma is poor biodegradable and carcinogenic, so the traditional physical and chemical or biochemical method is difficult to treat it effectively.Naphthalene is one of the most toxic polycyclic aromatic hydrocarbons(PAHs), is commonly found in the wastewater that is discharged from oil refineries, coking factory and fuel plant. Because of their toxicity, mutagenicity and carcinogenicity, PAHs have been listed as priority pollutants. Because of its stable bi-cyclic aromatic structure, Naphthalene is one of the most difficult PAHs for microorganisms to biodegrade.Adsorption method is an attractive technology which has been widely used for the removal of pollutants during advanced water treatment due to its low investment and operation costs. Natural zeolite is widely used to adsorb pollutions in water due to its low price, large specific surface area, and huge cavity, however, the natural zeolite has poor performance in adsorption of organic compounds due to its strong hydrophilic surface.In this study, natural zeolite was used as raw materials, cetyl trimethyl ammonium bromide(CTMAB), vinyl trimethoxy silane(VTMOS), trimethoxy silane(TMS) and trimethyl chlorosilane(TMCS)were respectively applied to modify natural zeolite, and four kinds of organic modified zeolite were prepared and characterized by specific surface area and pore size analyzer(BET), X-ray diffraction(XRD), infrared spectra(FTIR), scanning electron microscope(SEM), thermogravimetric analysis(TG) and contact angle meter. Adsorption of Rhodamine B and naphthalene in water by natural zeolite and the modified zeolite was studied by static adsorption method, the main conclusions are as follows:(1)Modifiers could be loaded on the surface of zeolite successfully and did not change the crystal structure of the raw zeolite, the hydrophobicity of zeolite surface has been improved, and the influence of heat resistance was not obvious;(2)VTMOS-modified zeolite has the better adsorption performance of Rhodamine B compared to other organic modified zeolite, the adsorption capacity increased by 11% than that of natural zeolite, the results suggested that the sorption of the Rhodamine B by VTMOS-modified zeolite followed Langmuir model very well.In addition,the quasi second-order kinetics model gave an acceptable fit to the experimental data.(3)When dosage is more than 10 g/L, CTMAB-zeolite has strong adsorption capacity of Rhodamine B, The influence of pH and temperature on the adsorption process is very small. Freundlich isothermal adsorption model can be used to describe the adsorption behavior, quasi secondary dynamics can be used to represent the adsorption dynamics process;(4)VTMOS-zeolite has better adsorption capacity of naphthalene, adsorption capacity reached 339 μg/g which increased by 32% than that of natural zeolite, 8% than that of CTMAB-zeolite, adsorption process is exothermic reaction, adsorption behavior can be described using the Langmuir isotherm adsorption model, quasi secondary dynamic model can be used to represent the adsorption kinetics;(5)The hydrophobicity increases after the natural zeolite was modified with VTMOS, which makes its adsorption to organic contaminant enhanced. So it could be used to remove the hydrophobic organic pollutants in the water.