Preparation Of Attapulgite/Activated Carbon Composite Adsorbent And Its Application In Wasterwater Treatment

With the rapid development of our country's industry,the demand for wastewater treatment remarkably.The printing and dyeing wastewater and heavy metals wastewater caused a great environmental hazards and are difficult to handle.It has become an urgent problem to be solved in the field of wastewater treatment.The attapulgite is a natural mineral that contain chain layer structure,and it is rich in magnesium aluminum silicate.It possesses well adsorption decolorization performance,ion exchange capacity,suspension property and thermal insulation properties,etc.,and these features made it is widely used in industries of sewage treatment,chemical,building materials,fire-retardant materials,etc.In this thesis,attapulgite,activated carbon powder,sesbania powder,and silica sol are used as raw materials to prepare a series of composite adsorbent materials by the method of extrusion molding,and these adsorbent are applied in the treatment of acidic brilliant blue wastewater and lead-containing heavy metal wastewater.It got a good removal resultThe effects of the ratio of carbon-clay,the addition of sesbania powder,the addition of silica sol and the calcination temperature on theperformance of the composite adsorbent were investigated.The structureof adsorbent was characterized by the scanning electron microscope,infrared spectroscopy,X-ray diffraction.The strength of the adsorbent was tested,and its adsorption performance was tested by single factor and adsorption isotherms experiments.The best acid brilliant blue and lead ionadsorbents are preferred.Adsorbent with the carbon-clay ratio of 25:25,sesbania powder addition amount of 10%,calcination temperature of 650? and silica sol addition amount of 40%has the best adsorption property for acid brilliant blue.The saturated adsorption capacity of static adsorption and lateral compressive strength were 15.51 mg/g,130.06 N/cm respectively.The removal rate of acid brilliant blue is proportional to the adsorption time and adsorbent dosage,and inversely proportional to initial dye concentration and pH value of the solution;Adsorbent with the carbon-clay ratio of 20:30,hydroxyapatite(Hap)addition amount of 1%,silica sol addition amount of 40%has the best adsorption property for lead ion.The saturated adsorption capacity of static adsorption was 3.03 mg/g and the lateral pressure strength was 147 N/cm for the best heavy metal adsorbent.The removal rate of lead ions increased with increasing adsorption time,adsorbent dosage and pH,and decreased as the initial concentration of heavy metal ions increased.It is concluded that the curve of adsorbent uptake capacities vary with adsorption time by adsorption kinetics experiment.It was confirmed that the acid brilliant blue and lead ion adsorption processes conformed to the pseudo first-order kinetic model and the pseudo second-order kinetic model,respectively.The adsorption isotherms at different temperatures(298K,308K and 318K)were measured to study the adsorption thermodynamics of the two adsorbents.It was found that the adsorption process was an endothermic process.It was concluded that the ?H of these reactions are beyond zero by calculating the relevant thermodynamic parameters,further confirming that it was endothermic process.