Adsorption Mechanism Study Of Mn²⁺ And Ni²⁺ In Wastewater By High Temperature Modified Sediment

Dredging project in Dianchi produced a lot of sediment, and accumulation in the continuous increasing,not only occupy a large amount of land resources, but also may cause serious pollution to nearby agricultural production, groundwater resources, ecological system.Sediment will be a long time after rain washed stockpiling and reflux of secondary pollution in Dianchi Lake.Therefore, it is an urgent problem to realize the comprehensive utilization of sediment, control the pollution of the sediment, improve the value of the resource utilization of the sludge, achieve the model of waste treatment and waste treatment, and create a good ecological environment.In addition, a large number of heavy metal waste water containing Mn²⁺ and Ni²⁺ can be produced in the process of manganese electrolysis and nickel electroplating, which seriously threaten the human health and the balance of and ecological environment system.In view of the above two questions,this paper using the sediment of Dianchi Lake as the absorption factor, after high temperature calcination instead of take out a new sediment adsorbent and preparation cost low,and investigate its wastewater containing heavy metals in the Mn²⁺ and Ni²⁺ adsorption effect, systematically studied the adsorption mechanism modified sediment containing Mn²⁺ and Ni²⁺ heavy metal wastewater.The carrier was prepared by calcination of modified adsorbent in the sediment of Dianchi, take sediment modified by examining the system optimal temperature conditions for 450℃,constant temperature roasting time 120 min, the specific surface area of the modified 42.9538 m2/g.Characterization of the adsorbent and the best sediment before and after （SEM、RI、XRD、BET） research and comparative analysis.By investigating the main factors affecting the experiment, the pH, the dosage of the adsorbent, the initial concentration of heavy metal wastewater, the adsorption time of the system, the adsorption temperature of the system.The optimal conditions of adsorption were as follows:pH value was 5-8,the dosage of adsorbent was 2 g/100 mL,the initial concentration was 10-30mg/L.the time of adsorption of Mn²⁺ was 130 min, the time of adsorption of Ni²⁺ was 150 min.and the adsorption temperature was 25℃.The adsorption equilibrium of Mn²⁺ and Ni²⁺ was in accordance with the Langmuir and Freundlich adsorption isotherm equations, but the adsorption process was more in line with the Freundlich adsorption isotherm equation, indicating that the adsorption was between monolayer and multilayer.Before calcination of sediment heavy metal ions adsorption stage, the Lagergren pseudo first order adsorption kinetic equation, the Lagergren pseudo second order adsorption kinetic equation,Elovich equation and Intra particle diffusion equation can Mn²⁺ and Ni²⁺.The research results show that the adsorption process followed the Lagergren pseudo second order adsorption kinetic equation, adsorption mechanism described by a chemical bond, film diffusion, surface adsorption, diffusion joint action within the particles, the adsorption process via chemical adsorption.The adsorption thermodynamic parameters （△S △H and △G） showed that the adsorption of Mn²⁺ and Ni²⁺ by high temperature calcined sludge was endothermic process, and the increase of temperature was beneficial to the spontaneous adsorption reaction.The results showed that the adsorption of Mn²⁺ and Ni²⁺ was mainly chemical adsorption, the chemical bond played a leading role in the adsorption process, therefore the adsorption stability regeneration difficulties and the regeneration effect is not ideal.The research results show that the high temperature roasting modified Dianchi sludge has a good adsorption effect on the wastewater containing Mn²⁺ and Ni²⁺, and the maximum adsorption capacity of Mn²⁺ and Ni²⁺ were 4.0755 mg/g and 3.6169 mg/g., respectively,which provides a new way for the sediment of Dianchi lake.