| Printing and dyeing wastewater accounts for a large proportion of our country's industrial wastewater,and it has become one of the sources of pollution that threatens the safety of our country's water environment.Among the water treatment technologies,flocculation method was widely used because it has the characteristics of easy operation,low-cost and easy industrialization.In this paper,flocculation method was used to achieve the decolorization of printing and dyeing wastewater,and a large amount of flocculation sludge wastes were obtained.Incineration and landfill were commonly used to treat the sludge wastes,which easily caused secondary pollution to the environment.Herein,we used flocculation sludge rich in nitrogen and sulfer as precursor for the preparation of heteroatom-doped carbon materials via simple pyrolysis method.It was applied in the field of electrochemistry and succeeded in transforming the flocculation sludge into treasures.This paper mainly does the following three parts of work.(1)Flocculant dicyandiamide-formaldehyde resin(DFR)was applied to the treatment of reactive brilliant red K-2BP dyeing wastewater.Research finding that the removal rate of K-2BP reached 97.3%and the adsorption capacity of K-2BP was 8000 mg g-1.N,S-doped porous carbon was prepared by controlling DFR content in pyrolysis precursor.Flocculant DFR plays the role of pore-forming agent in the pyrolysis process,and it can serve as soft template for the preparation of carbon materials.ORR test results in alkaline solution showed that the initial potential of NS-DF-2 is 0.98 V,the half-wave potential is 0.82 V,and the limiting current density is 5.56 m A cm-2,the electrochemical cycle stability and methanol resistance performance was better than commercial 20 wt%Pt/C.Supercapacitor performance test results showed that:the specific capacitance of NS-DF-2 can reach 230.5 F g-1 at 1 A g-1.The better electrochemical energy storage performance of the materials benefits from abundant micropores and mesopores.(2)Cationic flocculant BDATS applied to the treatment of printing and dyeing wastewater,under the optimal flocculation conditions,the decolorization rate of wastewater is 98%,and the adsorption capacity of K-2BP is 2030 mg g-1.We used flocculation sludge as precursor for the preparation of nitrogen and sulfur porous carbon materials KBC-X via Zn Cl2 salt sealing method.In the process of flocculation sludge pyrolysis,Zn Cl2 serve as a completely closed"micro-nano reactor".It was found that the content of nitrogen and sulfur in carbon materials prepared by salt sealing method increased significantly,as well as the specific surface area.Under alkaline conditions,the initial potential of KBC-2 is 0.93 V,which is equivalent to commercial 20 wt%Pt/C;the half-wave potential is 0.83 V,and the limiting current density is5.65 m A cm-2,which is better than commercial 20 wt%Pt/C.In addition,the materials have better stability after 5000 cycles of charging and discharging at the current density of 5 A·g-1(3)Flocculation sludge serve as precursor and added appropriate amount of ferric chloride,iron and nitrogen co-doped porous carbon materials Fe NC-X was synthesized by Zn Cl2 salt sealing method.Compared with direct pyrolysis,the content of iron and nitrogen in the carbon materials prepared by salt sealing method increased significantly,as well as the specific surface area.Under alkaline conditions,Fe NC-3 showed great ORR activity with initial potential of0.95 V,half-wave potential of 0.85 V,and limiting current density of 5.3 m A cm-2,which was close to commercial 20 wt%Pt/C.In addition,Fe NC-3 carbon material also has excellent stability and methanol resistance.In the three-electrode system,the specific capacitance of Fe NC-3 can reach 192 F g-1at 1 A g-1.At the same time,the material also has good cycling stability. |
PDF Full Text Request