Polymer Modified Bentonite For Adsorption Of Anionic Dyes

Bentonite is composed of silicon tetrahedron and aluminum oxide octahedron.There is a large amount of Na²⁺ and Ca²⁺ in its interlayer,so the bentonite has excellent cation exchange capacity and can adsorb cationic dyes in wastewater.However,for anionic dyes,the adsorption performance is not excellent.Therefore,it is necessary to improve the adsorption capacity of the anionic dye by modifying the bentonite.In normal,due to the small molecule-modified bentonite has less adsorption sites,adsorption performance is not ideal.Polymer modified bentonite,a new adsorbent,is the focus of this paper for treating anionic dyes in wastewater.In this paper,polyacrylloxyethyl trimethyl ammonium chloride modified bentonite,polymethyl methacrylate modified bentonite and polyethylene imide functional bentonite are introduced.The modified bentonite was characterized by infrared Spectroscopy?IR?,x-ray Diffraction?XRD?,scanning electron microscopy?SEM?,thermal gravity analysis?TG?.And selected target adsorbates are brilliant yellow?Brilliant Yellow,BY?and amino black 10B?Amino Black 10B?,which are both anionic dyes.The adsorption performance and optimum adsorption conditions of the whole adsorption experiment under different adsorption conditions are studied.At the same time,the adsorption kinetics and adsorption isotherm of the experimental data are analyzed,and the thermodynamic parameters calculated.The main contents are as follows:?1?In this paper,polyacryloyloxyethyltrimethylammonium chloride modified bentonite?Bent-PDAC?was used as the new adsorbent by free radical polymerization.The structure,morphology and organic components were analyzed by IR,XRD,SEM and TG.Experiments were carried out to select BY,the anionic dye,as the target adsorbate and the influence condition in the adsorption process was analyzed.Through the comparison of experimental data,results show that the maximum adsorption capacity of Bent-PDAC to BY is 302.9 mg/g.And with the increase of the initial concentration,the temperature and the time,the adsorption capacity increased and finally reaches the balance,while the p H has little effect on the adsorption capacity.Through the study of adsorption kinetics and adsorption isotherm for experimental data,the adsorption process is in accordance with the pseudo-second-order adsorption kinetics model and the Langmuir adsorption isotherm model.The adsorption process is the spontaneous endothermic process through the calculation of thermodynamic parameters.?2?Polyethylmethacrylate modified bentonite is prepared by the free radical polymerization method.Amino black 10 B,an anionic dye,is selected as the target adsorbate in the experiment,and the effects of pH,time,temperature and concentration on the adsorption capacity are discussed.The maximum adsorption capacity to amino black 10 B is 371.4 mg / g through experimental data,which is much higher than that of the bentonite.The experimental data show that with the increase of pH,the adsorption capacity decreases gradually.With the increase of initial concentration,temperature and time,the adsorption capacity increases gradually and finally reaches the adsorption equilibrium.The adsorption kinetics show that the adsorption process is in accordance with the pseudo-second-order adsorption kinetic model.The adsorption isotherm is in accordance with the Langmuir isotherm model,and the adsorption process is a spontaneous endothermic process.?3?Polyethyleneimine functionalized bentonite?Bent-GLYMO-PEI?is synthesized by reacting with an epoxy group grafted on a bentonite by polyethyleneimine,which is interconnected by covalent bonds.The results of the influencing factors of pH,initial concentration,temperature and time in the adsorption process show that the adsorption capacity decreases with the pH increases.While with the initial concentration,the temperature and the time increase,the adsorption capacity will increase and finally reach the balance.The maximum adsorption capacity of Bent-GLYMO-PEI to amino black 10 B is 327.7 mg/g.And the adsorption process is in accordance with the pseudo-second-order adsorption kinetics model and the Langmuir isotherm model,the adsorption process is a spontaneous endothermic process.?4?The three adsorbents have a large adsorption capacity for anionic dyes,and the synthesis method is simple,there are greater application value for the adsorption of dyes.