Study On Adsorption Properties Of Methyl Violet Or Neutral Red In Wastewater By Bentonite

The adsorption performances of methyl violet or neutral red onto natural oranionic organic bentonite were studied through batch experiment reserch. Theadsorption results of the adsorption by natural or anionic organic bentonite werecompared, and the external environment factors were discussed. Besides, thedynamics, two kinds of absorbent adsorption isotherm type and adsorptionthermodynamics were analyzesd. The research conclusion indicated:The adsorption results of methyl violet or neutral red onto natural or modifiedbentonite were pretty good, compared with natural bentonite, the adsorption results ofmethyl violet or neutral red onto anionic organic bentonite were better, and theadsorption results of neutral red onto natural or anionic organic bentonite was betterthan that of methyl violet.The influence factors on the adsorption such as bentonitedosage, dyes initial concentration, the initial pH and temperature were studied,indicating that: the removal rate of dyes increased with increasing bentonite dosages,temperature and pH, but dicreased with the increasing dyes initial concentration.The adsorption rates of methyl violet or neutral red onto natural or anionicorganic bentonite were fast, and the removal rates of two dyes were fastest in theinitial5minutes, finally, they reached balances until90minutes. Thepesudo-first-order model, pesudo-second-order model and intraparticle diffusionmodel described the adsorption process well, but the pesudo-second-order model wasthe best one.The dyes adsorption of methyl violet or neutral red onto natural or anionicorganic bentonite both fit well to Freundlich isotherm and Langmuir isotherm, but itfit better to Langmuir isotherm. The thermodynamic analysis H>0, indicating theexothermic reaction, increasing temperature was favorable for the adsorption, andthey were both <40KJ/mol, indicated that the adsorption was a physical controledprocess; S>0, indicated entropy of reaction increased. The G<0, indicated the adsorption was a spontaneous process at normal temperature. At the same temperature,with the increasing of the concentration of dyes in the solution, adsorption potentialgradually reduced.The adsorption of dyes onto bentonite was surface adsorption, ion exchangeabsorption and layer distribution adsorption. The adsorption of methyl violet andneutral red onto bentonite was physical surface adsorption.