Structure and Adsorption Properties to TVOC of Orange Peel Modified with KOH

Food waste orange peel was employed as a raw material to prepare biomass adsorbent to solve the indoor Total Volatile Organic Compounds (TVOC). The preparation process of orange peel treated with KOH was optimized by the quadratic regression orthogonal rotation, and the regression model and optimal processing conditions were obtained. The structure of the adsorbent was characterized by BET, SEM, TEM, EDS, XRD and FTIR analysis. The adsorption properties and desorption regeneration were discussed. The results showed the maximal removal rate Y-max was 9.4824% when KOH concentration was 0.3 mol/L, the soaking time of KOH was 26 h and that of HCl was 2.89 h. The best single factor condition was the adsorbent with 40 mesh size and 6.0 g. The adsorption of modified orange peel on TVOC conformed to the Freundlich models, which was more inclined to multi-layer active site adsorption. The adsorption law followed the quasi-second-order kinetic model (R-2 = 0.955), indicating the adsorption was a physico-chemical mixture but controlled by physical adsorption and it was a spontaneous endothermic process. The modified orange peel exposed more sites and had stronger chemical groups, which were beneficial to adsorption. The adsorbent has a significantly better TVOC removal rate than other materials at 1% level, that is, modified orange peel > diatomite > activated carbon > bamboo charcoal > macroporous resin. In addition, it had good recycling and regeneration capacity.