Characterization, Adsorption Properties and Mechanism of Modified Sophora Japonica Leaves to Benzene

The biosorbent has been prepared with the sophora japonica leaves from the agricultural residue as the raw material by the alkaline blanching method, and characterized by BET, SEM, EDS and FTIR analysis methods. The modified sophora japonica leaves possessed more adsorption sites and had more strongly adsorbed chemical groups, which were beneficial to the adsorption. We have further investigated the adsorption performance of the indoor benzene. The secondary regression orthogonal rotation was employed to optimize the preparation process for the optimal processing conditions and regression model. The effects of single factors such as particle size, temperature, and adsorbent dosage of the sophora japonica leaves were analyzed, and adsorption isotherms and adsorption kinetics were studied. The results show that the optimal adsorption conditions were as follows: sodium hydroxide concentration with 0.1 mol/L, water bath time for 70 min, water bath temperature at 60 ℃ and Ymax = 21.38%. The best single factors included particle size with 30 mesh, temperature at 25 oC, 3 g dosage, which are consistent with the Freundlich model, and the adsorption state was more inclined to multilayer active site adsorption with 25 mg/g of saturated adsorption amount;furthermore, the adsorption kinetics followed the quasi-secondary kinetic model(R2 = 0.9731) and the adsorption process was a physicochemical mixed adsorption process controlled by chemisorption;Compared with the adsorption effect, the removal rate to the benzene of modified sophora japonica leaves was significantly superior to other materials at the level 1%, namely, modified sophora japonica leaves > diatomite> bamboo charcoal > activated carbon > macroporous resin, and the modified biosorbent had a good cycle regeneration ability.