Walnut Shell Modified by Thionyl Chloride and Triethylamine: Synthesis and Characterization

A novel modified walnut shell (TWNS) was prepared through sequentially reacting the walnut shell (WNS) with thionyl chloride and triethylamine in N-methyl pyrrolidone to remove Reactive Brilliant Blue from dye wastewater. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) were used to characterize the TWNS. The effects of different experimental conditions such as the reaction temperature, the reaction time, the dosage of thionyl chloride and triethylamine on the quaternary ammonium grafting percentage of TWNS have been studied. The results reveal the quaternary ammonium grafting percentage (Y) is up to 18.37% when the dosage of thionyl chloride (V1) is 35 mL, the reaction time (t1) is 3 h in the first step reaction; the dosage of triethylamine (V2) is 40 mL, the reaction temperature (T) is 80°C and the reaction time (t2) is 12 h in the second step reaction.