Adsorption of methylene blue from water by citric acid modified orange peel

【Objective】 The effects of citric acid modification on the pollutant adsorbed by orange peel sorbents were discussed.【Method】 The crude orange peel(OP) was selected as raw sorbent material and was modified with citric acid to produce potentially sorbents,citric modified orange peel(COP) and basified citric modified orange peel(MOP).The dye methyl blue(MB) was chosen as the pollutant in the study.COP,MOP and OP were evaluated for their MB removal capacities from water by batch experiments.The effects of various experimental parameters(e.g.,initial pH,MB mass concentration,sorbent dosage,temperature) were examined,and the adsorption kinetics and thermodynamics were also discussed.【Result】 The ratio of MB sorbed on the 3 sorbents were controlled by the pH of the system.For the MOP sorbent,there was no significant change on the MB sorption when the pH stayed between 2-10.While the OP and COP sorbents reached the adsorption equilibrium when the pH was up to 6.Under the same temperature the order of maximum adsorption capacity was such as MOPOPCOP,and the maximum adsorption capacity was 112.45,27.59 and 189.92 mg/g for the OP,COP and MOP respectively under 30 ℃.The isothermal fitted the Langmuir model and the adsorption processes followed the pseudo-second-order rate kinetics,and the adsorption equilibrium could be obtained in 120 minutes,and the overall adsorption process was endothermic and spontaneous.【Conclusion】 The basified citric modified orange peel was a potential sorbent which can be used in the wastewater treatment and Absorb MB effectively.