Preparation Of Activated Carbon From Waste Residue Of Chinese Prickly Ash Seeds By Chemical Activation And Its Adsorption Properties

The waste residue of Chinese prickly ash seeds is a by-product of the pepper industry,it contains lignin,cellulose,etc.,and it can be good raw material for the activated carbon.In this paper,using Chinese prickly ash seeds residue as the raw material,a series of activated carbons were prepared via chemical activation methods,and the adsorption processes of organic dyes and heavy metal ions were studied.The dissertation mainly includes the following contents:1.Activated carbons were prepared from waste residue of Chinese prickly ash seeds activated by K₂CO₃.It was characterized by the methods of FT-IR,SEM,TG,EDS,XRD and N₂-adsorption-desorption.The effects of various process parameters were analyzed,such as impregnation ratio（mass ratio of K₂CO₃ to waste residue of Chinese prickly ash seeds）and time,and carbonisation temperature and time on the yield were analyzed.Under the conditions of impregnation ratio to 0.8,impregnation time of 12 h,carbonisation temperature at 550℃and carbonisation time of 60 min,the yield,specific area,iodine number,and the adsorption capacity of MB are 25.2%,1210 m²/g,1002 mg/g,and 362 mg/g,respectively.The ash and moisture weight are2.2%and 6.6%,respectively.Its adsorption properties for p-nitrophenol show the adsorption capacity could be achieved to 406.020 mg/g at temperature of 293 K,pH=8.0,after adsorbing for 180 min.Thermodynamics studies show the adsorption process can be favorably described by Langmuir isotherm,which is a spontaneous and exothermic process,in which（35）H is-13.186 kJ/mol and（35）S is-36.565 J/（mol/K）.And adsorption kinetics is better fitted to the pseudo-second-order model.2.Activated carbons were prepared from Chinese prickly seeds activated by H₃PO₄.It was characterized by the methods of SEM,EDS,N₂-adsorption-desorption,FT-IR and XRD.The effects of impregnation ratio（mass ratio of H₃PO₄ to Chinese prickly seeds）and time,carbonisation temperature and carbonisation time were analyzed.Under the conditions of mpregnation ratio to 0.4,impregnationtime of 10 h,carbonisation temperature at 550℃and carbonisation time of 60 min,the yield,specific area,total pore volume and pore diameter of activated carbon prepared are23.4%,740 m²/g,0.35 cm³/g,and 1.20 nm,respectively.Its adsorption properties for methylene blue investigation show the adsorption capacity could be achieved to449.402 mg/g when the initial concentration of methylene blue is 500 mg/L under the conditions of adsorption temperature at 323 K and pH=9.0 after adsorbed for 90 min.Thermodynamics studies show the adsorption process can be favorably described by Langmuir isotherm,which is a endothermic process,in which（35）H is 20.443 kJ/mol and（35）S is 81.319 J/（mol/K）.The adsorption kinetics is satisfactory fitted to the pseudo-second-order model.3.The modified activated carbon KAC-N and HAC-N were prepared by oxidizing KAC and HAC with HNO₃.They were characterized by the methods of FT-IR,SEM,EDS,XRD and N₂-adsorption-desorption.And the specific area and total pore volume of KAC-N and HAC-N are 743 m²/g and 646 cm²/g,0.43 cm³/g and0.24 cm³/g,respectively.The Cu²⁺,Ni²⁺and Cu²⁺,MO were adsorpted by the HAC-N in the binary-component system.The results show that the adsorption process can be favorably described by non-modified Sips isotherm.The adsorption kinetics is satisfactory fitted to the pseudo-second-order model.