Preparation Of Modified Coal Gangue Adsorbent And Study On Phosphorus Removal In Water

With the rapid development of agriculture and industry today,the amount of wastewater discharge is also increasing year by year,and the discharge of phosphorus is also rising.In some areas of the country,lakes,rivers and other water bodies often exceed the ammonia nitrogen and total phosphorus,especially in the economy Less developed cities below the fourth tier.Waste water containing nitrogen and phosphorus is discharged into the water body,which promotes the rapid and large-scale reproduction of algae and plankton,which leads to the eutrophication of the water body.At present,the common phosphorus removal methods in China are:biological method,chemical precipitation method,crystallization method and adsorption method.The adsorption method has the advantages of low operating cost,good phosphorus removal effect,and renewable adsorbent.Research and experiments using natural materials and industrial wastes as phosphorus adsorbents are hot topics today.Coal gangue contains a large amount of clay minerals obtained.Direct use of coal gangue as an adsorbent has low processing efficiency,long time,and a large amount of dosage required to meet the standard treatment.The crystallization water in coal gangue can be removed through modification Chemical reaction with the surface of coal gangue,dredge the channel,increase the specific surface area,greatly improve its adsorption performance,save adsorption time,improve phosphorus removal efficiency and reduce processing costs.The use of resource-rich solid waste coal gangue as a raw material to prepare an adsorbent through modification can find a reasonable way out for the recycling of coal gangue and also reduce the preparation cost.At present,there are few research reports on the use of modified coal gangue to remove phosphorus.The research of this subject has double meanings to solve the gangue and phosphorus removal of waste water,reuse solid waste,not only control environmental pollution,but also have economic and social benefits.Its research results can be secondary effluent of sewage treatment plant or natural lake The removal of medium dephosphorylate provides certain data and theoretical support.This topic uses experimental analysis,theoretical research and other means to modify zinc gangue on the basis of thermally modified gangue to determine the best preparation conditions for zinc-modified gangue,and analyzes the physical and chemical properties of zinc-modified gangue by characterization results Properties and modification mechanism,to explore the adsorption effect of thermally modified coal gangue and zinc modified coal gangue on phosphate in wastewater under different reaction conditions,to conduct adsorption kinetics,adsorption isotherms and adsorption thermodynamics studies,through SEM,XRD,The characterization results of XRF,FTIR and XPS analyzed the relationship between the structure and performance of modified coal gangue and the effect of phosphorus removal,and explored the mechanism of adsorption.To find a new way to solve the resource utilization of coal gangue and phosphorus removal from wastewater,the following conclusions were obtained:(1)After the raw coal gangue is calcined at 800?,the main chemical composition content has not changed much,and it is Si O₂,Al₂O₃,Fe₂O₃,Ca O,etc.,and after thermal modification,sintered agglomerates appear,the number of pores increases,and the pore diameter increases Many tiny layered crystals appear,and the adsorption capacity is enhanced.After the high-temperature calcination of kaolinite and calcite in the original coal gangue,the mineral structure changes,thereby activating the coal gangue.(2)The best preparation conditions of zinc-modified coal gangue:solid-liquid ratio 1:30,p H=7,temperature 30?,reaction time 1 hour,zinc chloride concentration 0.3mol/L.The adsorption capacity of zinc-modified coal gangue is 2.28 times that of thermally-modified coal gangue,indicating that zinc modification has a significant effect on the adsorption of thermally-modified coal gangue.And the main chemical composition of zinc-modified coal gangue has changed,the content of Zn O has been greatly increased,there are a lot of dense particulate matter and pore structure on the surface of the adsorbent,the surface is relatively rough,a large amount of zinc has been loaded on the coal gangue,may be hydrogen The presence of zinc oxide changes the structure of thermally modified coal gangue.(3)The thermally modified coal grinding stone is used to treat 100m L of simulated wastewater with a phosphorus concentration of 50mg/L.The optimal dosage is 3.5g/L.The adsorption reaction is greatly affected by p H and temperature.Ca²⁺and Mg²⁺promote the adsorption reaction.For zinc-modified coal gangue to treat the same wastewater,the optimal dosage is 1g/L.The adsorption reaction is greatly affected by p H.Ca²⁺and Mg²⁺promote the adsorption reaction.Both thermally modified coal grindstone and zinc-modified coal gangue conform to the pseudo-second-order kinetic model and Langmuir adsorption isotherm,and the adsorption of phosphorus is endothermic,spontaneous,and entropy increasing.At 20?,the maximum fitting adsorption capacity of zinc-modified coal gangue is 48.379mg/g,which is1.757 times higher than that of thermally modified coal gangue;at 30°C,the maximum fitting adsorption capacity is 68.46mg/g.Before sex,it increased by 2.481 times;at 40°C,the maximum fitting adsorption amount was 69.16mg/g.It increased by 1.519 times.And through the characterization analysis,the adsorption reaction of heat-modified coal gangue and zinc-modified coal grindstone to phosphorus is electrostatic adsorption on one hand,and more importantly,the metal light groups are coordinated and exchanged to form a precipitate.However,the phosphorus removal rate of zinc-modified coal gangue is significantly higher than that of thermally-modified coal gangue,because zinc supports the surface of the coal gangue and provides more active sites.(4)Comparing the adsorption of phosphorus between zinc-modified coal gangue and thermally-modified coal gangue,zinc modification can better remove high-concentration and low-concentration phosphorus,and the removal rate of 5mg/L phosphorus-containing wastewater can reach 97%.The adsorption capacity of zinc-modified coal gangue is higher.At different reaction temperatures,the adsorption capacity of the heat-modified gangue is increased by 1.5-2.4 times,and the saturation adsorption time is shorter.The zinc-modified coal gangue at room temperature and p H=4?7 There is a good adsorption capacity between each other,and the thermally modified coal gangue needs the phosphorus adsorption under strong alkali and high temperature conditions.The outgoing rate will be greatly improved,increasing operating costs.Therefore,zinc-modified coal gangue can significantly improve the adsorption performance and adsorption capacity of thermally modified coal gangue,and has a wider application range.