Sorption of Atrazine, 17α-Estradiol, and Phenanthrene on Wheat Straw and Peanut Shell Biochars

Abstract

Biochars from two different feedstocks (peanut shell-PB; wheat straw-WB) were used in this study to understand the sorption mechanisms of atrazine (ATR), 17α-ethinyl estradiol (EE2), and phenanthrene (PHEN) to help minimize the bioavailability of the organic pollutants in the environment. Sorption isotherms of ATR, EE2, and PHEN by WB and PB biochars followed the Freundlich model where the sorption parameter (n) shows the trend: ATR > EE2 and PHEN, while the sorption capacity (log K oc ) increases from ATR < EE2 < PHEN and indicate that the most hydrophobic and planar organic pollutant (PHEN) is the most easily adsorbed organic compound on PB and WB. The higher H/C and (O + N)/C ratios of WB (0.099 and 0.525, respectively) suggest its stronger aliphaticity and polarity than PB (0.078 and 0.352, respectively) that induced stronger sorption affinity for ATR and PHEN. Higher specific surface area (m2 g−1) of PB (19.7) may be responsible for the higher sorption capacity for EE2 than WB (8.8) because it can accommodate the large molecule of EE2. Results from this study may be helpful to predict the bioavailability of organic pollutants when soils contaminated with pollutants are remediated with biochars produced from wheat straw and peanut shells.