Removal Of Pollutants By Cost-effective Mesoporous Materials Synthesized From Calcium Fluoride Sludge

For the problem of Calcium Fluoride Sludge (CFS) and Waste Quartz Sand(WQS) disposal, this paper presented the CFS and WQS are recycled to synthesizeadsorbents, which are effective adsorbents for removal of various pollutants fromwater. The adsorption of Methylene Blue (MB) by Pore-expanded Calcium FluorideSludge (ECFS) which was synthesized using pore-expanded technology was studied.The adsorption performance and sequence of ammonium and heavy metals byzeolites, which was synthesized using CFS and WQS by hydrothermal method, wereanalyzed. Preparation of adsorbents synthesized from CFS and WQS, which hasdeveloped a recycling technology.The average pore size of ECFS, which was synthesized using urea aspore-enlarging agent at358K, was35.9nm. The equilibrium adsorption capacity ofCFS and ECFS were13.6and41.0mg g-1, respectively, at100mg L-1initial MBconcentration. The ECFS is a better adsorbent than CFS. Therefore, the increase ofthe materials’ pore size could improved the MB adsorption performance of thematerials. The adsorption of MB by ECFS was spontaneous and exothermic. Then,the overall rate constant of adsorption process appeared to be controlled by thechemical sorption process.The silicon gel was extracted from Waste Quartz Sand (WQS) by alkali melting.Then, CFS-Zs were synthesized using the silicon gel, sodium aluminate and CFS byhydrothermal method. The addition of CFS could decreased the pore size of thezeolite, but increased the BET surface areas and pore volume.When CFS addition waslower than10%, the ammonium removal of zeolite CFS-Z remained very high, at84.1%. When the Si/Al molar ratio was2, a mixture of zeolite A and zeolite X wascrystallized. By using the lower molar ratio (Si/Al<2), the samples was demonstratedto be that of zeolite A. When the CFS addition was10%and the ratio of Si/Al was0.5,the ammonium removal of zeolite CFS-Z was91.5%.CFS-Z was a good adsorbent for ammonium、Pb2+、Cr3+and Cd2+. The adsorption capacity of CFS-Z was25.7mg g-1at80mg L-1initial ammnoumconcentration. The ammonium adsorption capacity of CFS-Z was found to be best atpH=5. The adsorption of ammonium by CFS-Z was spontaneous and exothermic.Then, the overall rate constant of adsorption process appeared to be controlled by thechemical sorption process. At5mg L-1concentration of single heavy metal, theremoval of Pb2+、Cr3+and Cd2+were reached100%. In mixed solution, due to the freeenergy of hydration metal, the adsorption removal of Cd2+by CFS-Z is higher thanthe Cr3+, but lower the Pb2+. The adsorption sequence of ions on CFS-Z was asfollows: Pb2+＞Cd2+＞Cr3+.