Study On Treatment Of Two Kinds Of Cationic Dye Wastewater By The Adsorption-flocculation

Dye wastewater shows high chroma,high content of organic pollutants,complex components,biological toxicity.It will destroy the ecological balance and endanger the existence of aquatic organisms because of the difficulty of biochemical degradation.So it is necessary to find out a simple,efficient and low consumption wastewater treatment technics.Rectorite is widely used as a environmental adsorption material because of its ion exchange,adsorption and hydrophilicity properties.However,the dispersed slurry formed by swelling after adsorption makes solid-liquid separation difficult.Polymer flocculants show a good effect on settlement of organics and suspended solids.For rectorite,there is a synergistic effect between adsorption and flocculation during the process of dye wastewater treatment.In this thesis,efficiency and economical material rectorite was chosen to treating two different simulative dye wastewater.The rectorite-polymer flocculants system was also used to study the principles and parameters of two different dye wastewater cotains cationics.The mechanism was studied.The main conclusions of this paper are as follows:Adsorption-flocculation method shows an enhancement of removing dyes molecules,while has a good effect on reducing the difficulty of seperating solid and liquid of rectorite.It also reduce the adhesion of floc to the vessel wall,which makes it easy to clean.The removal rate of MB waste water by adsorption-flocculation method reaches 96.8%,which is 5%higher than that of single adsorption treatment.Parameters are:pH=12,1g/L of rectorit,30mg/L of NX-A7.The removal rate of NR waste water by adsorption-flocculation method reaches 90.9%,which is 30.4%higher than that of single adsorption treatment.Parameters are:pH unchanged,0.6g/L of rectorit,60mg/L of NX-A3.It has been found that the adsorption process of MB and NR on rectorite agrees very well with the pseudo-second order model by studying the adsorption dynamics research,this process also concluded particles diffusion effect;For adsorption isotherm,the study found the Langmuir adsorption isotherm model gave the better representation than Freundlich model according to R~2 values for MB and NR both.All of them belonged to monolayer adsorption.Through the study on the adsorption thermodynamics,the adsorption of MB and NR on rectorite reaction is spontaneous.Through the study on the mechanism of waste water treatment by flocculation,it implied that the charge neutralization and adsorption bridging exsit in the flocculation process of MB by NX-A3 and NX-A7.For NR,the break of chemical bonds in NR molecules was found accompanied by the charge neutralization and adsorption bridging.By comparing the SEM images of the rectorite before and after adsorption and flocculation and the removal rate of the adsorption treatment and the adsorption-flocculation process on the dye wastewater,it can be conclude that flocculants was not only has the effect of charge neutralization and adsorption bridging during the process of dye waste water treatment,but also combined with rectorite particles adsorbing dye molecules like bridging agents,which lead to fast settlement of adsorbent.The use of the compound has improved the pollutant removal rate and reduced the cost adsorption treatment,moreover,avoiding the second pollution in wastewater treatment.