Study On Preparation And Adsorption Properties Of Cell-open Foamed Concrete

Now,the treatment of wastewater containing chromium is one of the major environmental problems in our nation,and the porous material is often used for wastewater treatment because of its special pore structure.However,the pore structure of porous material has great influence on its properties and applications.Foamed concrete,which has a structure of closed air-void,was seldom applied in wastewater treatment.In order to solve the chromium containing wastewater treatment and provide certain technical support,this paper prepared the foamed concrete with open cell structure to treat the waste water,and its adsorption performance was studied.In this paper,the cell-open foamed concrete with 400kg/m3 was designed and prepared by physical foaming method with Ordinary Portland cement and foaming agent.The effects of water cement ratio,dilution ratio of foaming agent,foam content,foam density and curing system on the pore structure of cell-open foam concrete were studied.Besides,the adsorption properties of Cr(III)in simulated wastewater containing chromium were studied by using the cell-open foam concrete as adsorbent.The author studied the effect of adsorbent dosage,adsorption time and adsorption temperature on the adsorption performance.What' s more,the adsorption kinetics and thermodynamics were built and the effect of adsorption column height,initial concentration and flow rate on the dynamic adsorption performance was studied.In the end,the paper also fitted the breakthrough curve.The results show that,when the water cement ratio is 0.35?0.55,the foaming agent liquid concentration is 2:70,the foam content is 11%and the foam density between 36kg/m3?51kg/m3 we can prepare the open cell foam concrete with the dry density of 400kg/m3 and its opening rate of pore is 45%?59%.The adsorption test showed that:(1)static adsorption experiment:when the adsorbent was 0.3g,the adsorption rate reach 98%and the adsorption process accorded with the Pseudo-second order kinetic model and Langmuir isotherm adsorption model.(2)dynamic adsorption experiment:when the initial concentration of simulated wastewater containing Cr(?)is 85mg/L,the solution flow rate is 7.5mL/min,the adsorption column height is 19cm,the time of break-through is 1260min,the adsorption efficiency can be 81%.The adsorption behavior accords with the Thomas model and the Yoon-Nelson model,and the diffusion of the adsorbent surface and the internal diffusion is not the rate controlling step.