Study on the Preparation of Modified Coal Gangue Fluoride Adsorbent and Its Adsorption Laws for Fluoride
The issue of elevated fluoride levels in Chinese groundwater and mine water is notably pronounced,with con-centrations typically ranging from 1 to 10 mg/L.This significantly constrains potential uses and escalates water treatment costs.Due to the substantial alumina content in coal gangue,its adsorption and removal capacity can be enhanced through modification.This study utilized high-silica,alumina-rich coal gangue as a raw material,loading zinc chloride for modifica-tion through high-temperature roasting.The modified gangue was characterized using SEM,XRF,organic elements and low-temperature liquid nitrogen adsorption analysis.Optimal modification conditions for the gangue were determined through single-factor experiments.Furthermore,the study investigated its adsorption kinetics and isothermal adsorption mechanism concerning fluorides,simultaneously conducted toxicity leaching testing experiments on coal gangue.The study demonstrates a significant enhancement in the activity of coal gangue following modification.The volatilization of inter-nal organic components increases the porosity and specific surface area,which markedly improves its adsorption capacity.Under optimal modification conditions of 400 ℃ calcination temperature,2 h of calcination time,and a material ratio of coal gangue to ZnCl2 at 1∶0.35,the fluoride removal rate from 10 mg/L wastewater reaches 91.87％,with an adsorption capacity of 91.87 mg/kg.The adsorption of fluoride by modified gangue conformed to the second-order kinetic model and Freundlich isotherm model,and the adsorption process is mainly physical adsorption,which belongs to multi-layer adsorption on non-uniform surfaces,and the adsorption process is relatively easy to carry out.In the initial stages,intra-particle diffusion primari-ly governed the adsorption process,while the influence of the modified gangue boundary layer on the adsorption process was minor.The toxicity testing experiment on modified coal gangue shows that the leaching toxicity of coal gangue is relatively low and can be used as a water treatment agent in the environment.These results offered crucial theoretical guidance for achieving high value-added utilization of coal gangue and reducing defluorination costs.
万方数据
维普
