高温改性蛋壳对废水中磷的吸附研究

Absorption Performance of Phosphorus on High-Temperature Modified Eggshell in Wastewater

基于蛋壳富含碳酸钙成分,采用高温改性方法制备蛋壳吸附剂,考察其对溶液中磷的吸附性能.比表面积、孔径和热重分析(TGA)结果表明,EC900的比表面积、孔容和孔径最大,EC在835～880℃失重率达44.03%,有CaO生成.高温改性蛋壳对磷的吸附性能优于原蛋壳,其中EC900最优.吸附动力学实验表明:EC800、EC900的吸附平衡时间为60 min,平衡吸附量为0.497、0.507 mg·g-1;EC、EC500、EC600、EC700的吸附平衡时间为120 min;蛋壳吸附剂投加量增大,单位磷吸附容量降低,投加量为2.0 g时,单位磷吸附容量为0.6～0.7 mg·g-1;同一投加量下,蛋壳吸附剂的单位磷吸附容量随溶液初始含磷浓度的增大而增加.吸附热力学实验表明,蛋壳吸附剂对磷的吸附是吸热过程,体系温度35℃时,EC900对磷的吸附转变为自发过程,吸附容量为1.89 mg·g-1.

Based on eggshells rich in calcium carbonate, a series of eggshell absorbents are prepared via high-temperature modification method to investigate the properties of phosphorus absorption in solution. The physicochemical properties of these modified eggshells have been examined by BET, pore size, TGA. The results show that EC900 has the largest specific surface area, pore volume and pore size;the weight loss rate of EC is 44.03% in 835 ~ 880 ℃, meanwhile, the CaO is produced. The phosphorus absorption performance is better than that of the original eggshell after modifying at high-temperature, where EC900 is the best. Absorption kinetics experiments show the absorption equilibrium time of EC800, EC900 is 60 min and the equilibrium absorption amount is 0.497, 0.507 mg·g^-1, respectively;the absorption equilibrium time of EC, EC500, EC600, EC700 is all 120 min. The adsorption capacity of unit phosphorus is 0.6~0.7 mg·g^-1 when the eggshell adsorbent dosage is 2.0 g, which is significantly reduced with the increasing of dosage and improved with the increasing of initial phosphorus concentration of the solution. Absorption thermodynamic experiments indicate the phosphorus absorption of eggshell absorbent is an endothermic process, the phosphorus absorption of EC900 turns into a spontaneous process when the system temperature is 35 ℃, and the absorption capacity is 1.89 mg·g^-1.