Preparation Of Biomass-based Carbon Materials And Their Adsorption Properties Of Macromolecular Dyes

China’s textile printing and dyeing industry accounts for about 7%of the world’s total exports,and dye wastewater has become an important pollutant in China’s industrial system.Dye wastewater has high pollutant concentration（high COD value）,high salinity,high toxicity,deep color,and low nitrogen and phosphorus content.It is one of the difficult industrial wastewaters to treat.Among the textile wastewater with the largest discharge of dye wastewater,reactive dyes are extremely toxic due to the heavy metals loaded,and biodegradation is the most difficult.Bromocresol green（BCG）is a typical acidic macromolecular dye as a reactive dye.The BCG dye in wastewater has strong stability in an aerobic environment.The residual dye in the soil penetrates into the surface water to bring harmful substances into the food chain.It can also cause mutagenesis,chromosome breakage,carcinogenesis and respiratory infections and other hazards,which will further adversely affect the health of humans and wild animals and plants and the entire aquatic ecosystem.Therefore,the adsorption treatment of BCG wastewater cannot be delayed.However,the BCG processing technology is not mature,and there are still certain difficulties in governance.In areas with high environmental quality requirements,the processing costs are relatively high.Therefore,in order to prevent the deterioration of water quality,we must adopt more efficient treatment technologies.Adopting the adsorption method to treat BCG dye wastewater is not only efficient,it can adsorb multiple pollutants at the same time,but also meets sustainable development.However,the current commercial activated carbon used to adsorb BCG has a high regeneration cost and cannot be popularized.In response to this problem,this article takes BCG in dye wastewater as the target adsorbent,and selects the abundant and cheap biomass in nature as the carbon source to prepare chito-oligosaccharide-based carbon materials,grape seed-based porous carbon materials,and sawdust-based mesoporous carbon material.The stability,pore structure,and surface functional groups of activated carbon was characterized by using thermogravimetry,N₂ adsorption/desorption isotherms and infrared.The adsorption performance of a series of carbon materials on BCG in dye wastewater,has been studed.Different reaction conditions and The effect of adsorption conditions on the adsorption performance of BCG has been explored too.Finally obtain the best preparation plan of mesoporous carbon for adsorption of BCG.The specific research content is as follows:1.The preparation of chitosan-oligosaccharide-based carbon materials by soft template method and the study on the adsorption properties of BCG.In this thesis,mesoporous carbon materials were prepared by soft template method using chitosan oligosaccharide as the carbon source;triblock copolymer surfactant as a template and the KCl as a stabilizer to reduce the reaction temperature.Their adsorption performance to BCG have been measured.Studies have shown that with the increase of KCl addition,the pore volume of carbon materials gradually increases;with the decrease of reaction temperature,the pore size distribution of carbon materials becomes narrower;with the increase of carbonization temperature,the mesoporosities of carbon materials increases.The mesoporous carbon KMC-900 was prepared with F127 as template,KCl addition amount 8g,reaction temperature 25℃,carbonization temperature 900℃,BET specific surface area 40.852 m²·g^-1,mesoporous pore volume 0.284 cm3·g-1.Its unit adsorption capacity for BCG is 0.103g/g.2.Study on the preparation of grape seed-based porous carbon material by salt template method and its adsorption performance for BCG.Using low-cost environmentally friendly waste biomass grape seed as a carbon source,using cheap KCl and Zn Cl2 eutectic salts as templates,porous carbon materials were prepared by the salt template method,and the effect of pore structure on the adsorption performance of BCG was determined.Studies have shown that the mesoporous content of porous carbon increases after ball milling.As the mass ratio of grape seed to template agent increases,the pore volume of the carbon material first increases and then decreases;as the carbonization temperature increases,the mesoporosities of the carbon material increases.Increase.The mass ratio of grape seed to template is 6,and the raw material is pretreated by ball milling,and carbonization at 700°C is the best reaction condition.The prepared porous carbon material has a BET specific surface area of 521.730 m²·g^-1,a mesopore volume of 0.088 cm³·g^-1,and a unit adsorption capacity of 0.443 g/g for BCG.3.Phosphoric acid activation method to prepare sawdust-based mesoporous carbon materials and research on the adsorption performance of BCG.Using low-cost wood waste as the carbon source and phosphoric acid as the activator,the mesoporous carbon material was prepared by the phosphoric acid activation method,and the effect of the pore structure on the adsorption performance of BCG was measured.Studies have shown that with the increase of the impregnation ratio（mass ratio of wood chips to phosphoric acid）,the pore volume of carbon materials first increases and then decreases;with the increase of activation temperature,the mesopore volume of carbon materials first increases and then decreases.The immersion ratio of 4,500℃is the best reaction condition.The BET specific surface area of mesoporous carbon M4-500℃is 1987.43 m²·g^-1 and the mesoporous pore volume is 1.382 cm³·g^-1.The unit adsorption capacity is 4.555g/g.Finally,five different biomass waste materials（walnut shells,distracted wood,bamboo shavings,grape seeds,pumpkin seed shells）were selected as carbon sources to prepare a series of carbon materials for the versatility of the BCG adsorption method.