Research On The Adsorption Efficiency And Mechanism Of Malachite Green Based On Manganese Modified Activated Carbon

Dye has excellent dyeing function,widely used in leather,textile,printing and dyeing industry,plays a huge role in life and production.However,the incomplete treatment of dye wastewater directly discharged into natural water will bring about changes in water color and soil pollution,and even affect public health and ecological security.In order to make up for the blank of this part,this thesis puts forward the idea of comparative comprehensive analysis of activated carbon modified by different manganese compounds,and takes the adsorption capacity of adsorption materials for malachite green(MG)as the evaluation index to realize the comparison of adsorption properties based on the same raw material and different modification methods.The specific work is as follows:(1)Based on the obtained granular coconut shell activated carbon(YC-1),the optimal preparation and characterization of potassium permanganate and manganese dioxide modified carbon were carried out;(2)The influence of environmental parameters on the adsorption of MG by different modified carbons was studied;(3)The adsorption kinetics,isotherms and thermodynamic adsorption model curves of MG on different modified activated carbons were fitted,and the adsorption mechanism of MG on modified activated carbon was revealed;(4)The regeneration properties of different modified carbons were explored.The main conclusions are as follows:(1)Based on the original adsorption material YC-1,YC-2 was prepared by KMnO₄impregnation method under the optimal preparation method,and its saturated adsorption capacity was 88.43 mg/g;YC-3 was prepared by MnO₂loading modification under the optimal preparation method,and its saturated adsorption capacity was 185.25 mg/g.Compared with YC-1,the saturated adsorption capacities of YC-2 and YC-3 increased by 28.26 and93.26 mg/g,respectively,reaching the goal of improving adsorption performance based on raw material modification.(2)Through the characterization analysis of carbon before and after modification,the changes of physical structure and chemical properties of YC-1 by different modification methods were summarized.The results showed that compared with YC-1,the specific surface area of YC-2 decreased by 134.138 m~2/g,and the total pore volume decreased by 0.084 cm~3/g.The specific surface area of YC-3 increased by 161.333 m~2/g,and the total pore volume increased by 0.103 cm~3/g.Scanning electron microscopy showed that the pores on the surface of the modified carbon increased and particles adhered to the surface.X-ray diffraction analysis confirmed the successful loading of manganese dioxide and other manganese oxides.Fourier transform infrared spectroscopy and thermogravimetric analysis showed that the number of acidic oxygen-containing functional groups on the modified surface increased.(3)In the static adsorption experiment,coal granular carbon(MC-1)and corresponding modified carbons MC-2 and MC-3 were added to the adsorption materials.The effects of MG initial concentration,adsorption time,temperature,p H and inorganic ions on the adsorption of MG by different modified carbons were studied,and the adsorption properties of different modified carbons were investigated.The results showed that the adsorption capacity of activated carbon increased with the increase of initial concentration,temperature and p H;increasing to balance over time;it decreased slightly with the addition of cations,increased slightly with the addition of anions,and affected significantly with the increase of coexisting ion concentration.Under the same adsorption conditions,the order of adsorption effect was YC-3>YC-2>YC-1,MC-3>MC-2>MC-1 and coconut shell carbon>coal carbon.(4)The adsorption kinetics,isotherms and thermodynamic model curves of MG on modified activated carbon were fitted.The results showed that the adsorption process of MG on modified carbon conformed to pseudo-second-order kinetics and Langmuir isothermal adsorption model,indicating that the adsorption process was monolayer adsorption dominated by chemical adsorption.In addition to internal diffusion,there are other control mechanisms;the adsorption of MG by modified carbon was a spontaneous endothermic reaction.(5)The effects of hydrochloric acid concentration,regeneration temperature and regeneration time on the regeneration performance of saturated YC-2 and YC-3 were investigated.The results showed that the saturated adsorption capacity of regenerated YC-2and YC-3 for MG increased with the increase of hydrochloric acid concentration,regeneration temperature and regeneration time.Under the conditions of hydrochloric acid concentration0.5 mol/L,regeneration temperature 25?and regeneration time 3 h,the adsorption capacity of YC-2 and YC-3 can still reach 83.3%of the original equilibrium adsorption capacity,indicating that activated carbon modified by manganese has certain regeneration value.