Modification And Application Of Activated Carbon For Azo Dye Wastewater Purification

The rapid development of industrialization has promoted the use of synthetic dyes and the discharge of wastewater,which has facilitated the research of dye wastewater treatment.Activated carbon is widely used in the treatment of industrial wastewater due to its developed pore structure and recyclability,resulting in a large amount of spent activated carbon.If the spent activated carbon cannot be disposed or utilized efficiently,it will cause serious impacts on the environment and human health,so the treatment of spent activated carbon has become an inevitable trend.In this work,the spent activated carbon from by production process of paracetamol treated by ultrasonic cleaner was used as raw material,regenerated activated carbon?R-AC?obtained by microwave roasting,the bismuth-loaded activated carbon?Bi-AC?and the copper-loaded activated carbon?Cu-AC?prepared by impregnation-microwave roasting were applied to the treatment of azo dye wastewater.The main research contents and results were as follows:?1?The optimum experimental conditions of R-AC were roasting temperature of 800°C,roasting time of 30 min and the methyl blue adsorption value of 180 mg/g,the yield of80.2%.The optimum experimental conditions of Bi-AC were roasting temperature of900°C,roasting time of 20 min and the methyl blue adsorption value of 195 mg/g,the yield of 64%.The optimum conditions of Cu-AC were roasting temperature of 800°C,roasting time of 20 min and the methyl blue adsorption value of 215 mg/g,the yield of50.7%.?2?The physicochemical properties of activated carbon before and after modification were characterized by nitrogen adsorption-desorption,XRD,SEM,XPS,Raman and Zeta potentials.The R-AC had a specific surface area of 869 m²/g and was mainly composed of C and O with a smooth surface.The Bi-AC had a specific surface area of1040 m²/g and was composed of C,O,Bi and?-Bi₂O₃.Bi or?-Bi₂O₃ was worm-like loaded on the surface.The Cu-AC had a specific surface area of 1160 m²/g and was mainly composed of C,O,Cu and Cu₂O,the Cu and Cu₂O were loaded on its surface with spherical particles.?3?The removal efficiency of methylene orange?MO?dye by R-AC,Bi-AC and Cu-AC were related to the initial pH,concentration of dyes and contact time.The adsorption isotherms of R-AC,Bi-AC and Cu-AC for MO were consistent with Langmuir model.The maximum adsorption capacity of R-AC,Bi-AC and Cu-AC were 340 mg/g,352.5mg/g and 377 mg/g,respectively.The adsorption kinetics fitted well with pseudo second model.?4?The Bi-AC and Cu-AC have the photocatalytic performance for MO and Congo red?CR?under ultraviolet and visible light irradiation.Compared with the two dyes,CR dye have obvious photocatalytic degradation efficiency.