Abstract: Objective: To explore the reutilization of wasted peels. Pomelo peels were used as raw materials to prepare biochar, and
zinc chloride solution was used to activate the pomelo peels to enhance adsorption performance of biochar derived from pomelo peel, so as to improve the application potential of biochar derived from pomelo peels in agriculture, industry and environment and so on.
Methods: The optimum conditions of pomelo-peel biochar activated by zinc chloride for methylene blue（MB）was studied by a L16 （45）orthogonal test, and the results were analyzed by a range analysis and the general linear model of single variable analysis with SPSS.Results: The effects of five factors on the adsorption properties of biochar for MB were: carbonization activation temperature > zinc chloride solution concentration > solid-liquid ratio > carbonization activation time > impregnation time. At the same time, the results of the orthogonal test and the single factor test were compared, which showed that the optimum conditions of activated pomelo-peel biochar for the adsorption of MB were as follows: solid-liquid ratio（g/mL）at 1 : 4, zinc chloride solution concentration at 40%,impregnation time at 14 h, carbonization activation temperature at 600 ℃, and carbonization activation time at 20 min. Conclusion:Orthogonal test and single factor test were combined to obtain the optimum preparation conditions of biochar derived from pomelo peels for adsorbing MB.

Key words: zinc chloride, pomelo peel, biochar, methylene blue, orthogonal test