Study On The Preparation And Characteristics Of Phosphorus Adsorption In Water By Expanded Ceramsite Synthesized Via Dredge Sediment-Marble Waste Powder

With the rapid development of China’s social economy,the discharge of a large number of industrial and agricultural wastewater has led to increasingly serious river pollution,resulting in an increasing number of dredged sediment;marble industry is one of the key industries in Guangxi,which produces about 800000 tons of marble waste powder every year.If the dredged sediment and marble waste powder are not treated and disposed properly,it will cause serious environmental pollution.Therefore,it is an urgent environmental protection problem to realize the resource utilization of dredged sediment and marble waste powder.Based on the dredged sediment（DSⅠand DSⅢ）and marble waste powder（MWP）from the ancient Guilin Liuzhou canal,the preparation of burnt expanded ceramsite was carried out,and the prepared ceramsite was applied to remove phosphorus from water.Through orthogonal test,the best raw material ratio and process parameters for preparation of high-efficiency phosphorus removal ceramsite filter material（dmcp）and high-strength building lightweight aggregate（DMCC）were determined,and some performance tests and characterization were carried out.The static adsorption test was designed to study the influence of different factors on the phosphorus adsorption performance of ceramsite.The phase,functional groups and element changes of ceramsite before and after phosphorus adsorption were compared One step analysis of its phosphorus removal mechanism,and through the application test of ceramsite dynamic adsorption column,to analyze its development potential in engineering application.The main conclusions are as follows:（1）According to the results of orthogonal test,the optimum raw material ratio of high strength building lightweight aggregate（DMCC）was determined as DSⅠ:DSⅢ:MWP=2:1:0.8,the preparation process parameters were preheating time 5 min,roasting temperature 1180℃,roasting time 15 min,the bulk density was 1080.35 kg·m³,the water absorption was 1.5%,the compressive strength was 25.53 MPa,and the related indexes were（GB/T）17431.2-2010"lightweight aggregates and their test methods Part 1:experimental methods of light aggregates"conforms to the range of high-strength lightweight aggregate;the optimal raw material ratio for the preparation of high-efficiency phosphorus removal ceramsite filter material（DMCP）is determined as DS I:DS III:MWP=2:1:0.8,preparation process parameters are preheating time 10min,roasting temperature 1060℃,roasting time 10 min,and its bulk density is 696.29The results show that,the porosity is 52.23%,the water absorption rate is 33.42%,the compressive strength is 2.37mpa,the sum of crushing rate and wear rate is 4.12%,the solubility of hydrochloric acid is 1.56%,and the specific surface area is 2.06 m²·g^-1.the relevant indexes all meet the standard of（CJ/T 299-2008）artificial ceramsite filter material for water treatment.（2）According to the XRD analysis before and after sintering,the main peak of Ca CO₃ in DMCP disappears,and new diffraction peaks of Cao,Ca（OH）₂ and Mg O appear.The analysis of bet and SEM shows that the internal structure of DMCP is mainly mesoporous.Comparing the element changes of DMC before and after sintering,it is found that the content of C and O in DMCP decreases,and the content of exchangeable Fe,Mg and Ca ions in DMC is increased.These preliminary analyses indicate that there are physical and chemical adsorption processes in the process of phosphorus removal by DMCP.（3）The static adsorption test showed that with the increase of DMCP dosage,the phosphorus removal rate increased and the adsorption capacity decreased;with the increase of initial phosphorus concentration,the phosphorus removal rate decreased and the adsorption capacity increased;the presence of interference ions SO₄^2-and CO₃^2-inhibited the phosphorus removal effect of DMCP;when the initial p H value of the solution was in the range of 2～12,DMCP could remove phosphorus effectively Maintain above 99%.（4）Among the kinetic models,the pseudo second order kinetic model has the highest fitting degree;Langmuir,Freundlich and Tempkin adsorption isotherm models can well describe the adsorption process of DMCP phosphorus;thermodynamic analysis shows that the adsorption of phosphorus by dmcp is spontaneous,and the adsorption reaction belongs to endothermic reaction;Arrhenius formula has a high fitting degree,indicating that the adsorption process of DMCP is chemical adsorption At the same time,there are some physical adsorptio-n.According to the changes of p H,FTIR、XRD and EDS analysis before and after DMC adsorption,it can be concluded that there are surface electrostatic adsorption,coordination exchange and chemical precipitation in the adsorption process of DMCP phosphorus,which is mainly combined with coordination exchange and chemical precipitation.（5）In the dynamic adsorption column test,the dynamic adsorption performance of DMCP for phosphorus increased with the increase of its height In the adsorption column with DMCP as adsorbent,the highest adsorption efficiency can reach 88.12%.In the actual removal project,more than 80%of the removal efficiency has reached the ideal effect.Therefore,the application of DMCP as adsorbent in dynamic continuous adsorption process has certain development potential.