Study On The Preparation Of Calcined CaMgAl Layered Double Hydroxides And Its Phosphorus Removal Performance

In order to solve the problem of phosphorus wastewater pollution,this paper has optimized and selected a variety of adsorption phosphorus removal materials,and carried out in-depth research on the preparation process and phosphorus removal performance of the preferred calcined Ca Mg Al-LDHs,In order to develop a high-efficiency adsorption phosphorization removal material,this research has certain theoretical significance and practical engineering application value.（1）The static adsorption experiment was conducted to compare the phosphorus removal effects of steel slag and modified steel slag,paper white mud and modified paper white mud,and calcined Ca Mg Al-LDHs,the Ca Mg Al-LDHs（CMA-0.83）with Ca:Mg:Al molar ratio of 5:1:2in the mixed metal salt solution during preparation has a hydrocalumite structure,and its calcined product has a better phosphorus removal effect than other materials.The calcined Ca Mg Al-LDHs is an excellent adsorption phosphorization removal material.（2）The research of the preparation process,influencing factors of phosphorus removal,phosphorus removal performance,phosphorus removal mechanism and analytical regeneration performance of the preferred calcined Ca Mg Al-LDHs was conducted through the static adsorption experiment combined with XRD,SEM,FT-IR microanalysis and the results are as follows:1)The best preparation conditions of CMA-0.83 are coprecipitation reaction temperature of65℃and coprecipitation reaction pH of 10.Under this condition,CMA-0.83 has a single crystal phase and a good layered structure,it is further modified and activated by calcining,As the calcining temperature increases,the phosphorus removal effect after activation increases first and then decreases.When the calcining temperature is 600℃,CCMA-0.83-600 forms Ca₁₂Al₁₄O₃₃,MgO,CaO,the phosphorus removal rate can reach 99.75%,which has an excellent adsorption and removal effect of phosphorus.2)Through single factor experiment and orthogonal experiment,the main influencing factors of the treatment of phosphorus wastewater by CCMA-0.83-600 are the dosage of adsorbent,initial phosphorus concentration and initial pH,the optimal initial phosphorus concentration and the addition of adsorbent of adsorption reaction is 100 mg/L,0.08 g,the optimal pH is 4,and the adsorption capacity can be kept high in the range of pH 3-8,the inhibitory ability of common anions to phosphate adsorption increases with the number of charges and ion concentration.3)The adsorption process of phosphate by CCMA-0.83-600 conforms to pseudo-second order kinetics model,the adsorption is dominated by chemical adsorption,and the adsorption conforms to the Langmuir isotherm adsorption model,the saturated adsorption capacity at 15℃,25℃and 35℃are 130.79 mg/g,149.91 mg/g and 161.66 mg/g,respectively,the adsorption is a spontaneous endothermic reaction,increasing the temperature is beneficial for positive direction of adsorption,the confusion degree of the system increases and the orderliness decreases during the adsorption process.The adsorption mechanism of phosphate by CCMA-0.83-600 is the comprehensive effects with physical adsorption,anion intercalation,ion exchange,surface complexation and chemical precipitation.4)10%Na₂CO₃solution has the best analytical effect of phosphorus-loading CCMA-0.83-600,the phosphorus adsorption capacity after analysis is 87.98%for the first time.phosphorus adsorption capacity after analytical regeneration gradually decreases as the number of analytical regeneration increases.The optimal number of analytical regeneration is three,the accumulatedphosphorusadsorptioncapacityafterthreetimesof analysis-regeneration-adsorption is 356.86 mg/g.The above research results provide a theoretical basis for the treatment of phosphorus wastewater by CCMA-0.83-600.CCMA-0.83-600 is an excellent adsorbent material for the treatment of phosphorus wastewater and is worthy of widespread popularization and application.The paper has 42 figures,19 tables and 78 references.