TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups...TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups in the two cellulosic samples oxidized using TEMPO/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,respectively.The oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic conditions.The kinetic model of TEMPO-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order model.The initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by TEMPO-oxidized cellulose conformed to the Langmuir model.The dye removal efficiencies for methylene blue and rhemazol yellow FG using TEMPOoxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,respectively.These results demonstrate that TEMPO/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye mixtures.Furthermore,the use of TEMPO-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.展开更多
文摘TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups in the two cellulosic samples oxidized using TEMPO/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,respectively.The oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic conditions.The kinetic model of TEMPO-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order model.The initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by TEMPO-oxidized cellulose conformed to the Langmuir model.The dye removal efficiencies for methylene blue and rhemazol yellow FG using TEMPOoxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,respectively.These results demonstrate that TEMPO/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye mixtures.Furthermore,the use of TEMPO-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.
