INTERACTION ADSORPTION OF p-NITROPHENOL AND Cu(II) BY CORN STRAW BIOCHAR

Corn straw was used to prepare biochars at 300 C and 600 C (CC300 and CC600). Characterization experiments showed that the BET surface area of CC600 (405 m2"g-1) was significantly higher than that of CC300 (4.19 mLg-'). The obtained biochars were used to absorb para-nitrophenol(PNP) and Cu(II) from aqueous solution simultaneously by batch experiments. In the binary system. 200 mg"L-1 of PNP was a critical value, that was, when PNP initial concentration was below 200 mg"L-1, the addition of Cu(II) had almost no effect on PNP adsorption by CC300 and CC600. While PNP initial concentration was above 200 mg"L-1, the PNP adsorption on CC600 was inhibited by Cu(II), whereas the PNP adsorption on CC300 was promoted by Cu(II). However, the existence of PNP improved the Cu(II) adsorption on the two biochars. The experimental data were fitted by Langmuir, Freundlich, Temkin and Langmuir-Freundlich isotherm models. The fitted parameters indicated that Langmuir-Freundlich described the isothermal adsorption behavior well. The maximal theoretical adsorption capacities of PNP and Cu(II) on CC600 were 78.1 mg"g1 and 95.5 mg"e, respectively. But the optimal adsorption capacities of PNP and Cu(II) on CC300 were 122 mg"g1 and 97.9 mg"g1, respectively. The adsorptions of PNP and Cu(II) on biochars were tended to the monolayer adsorption, but not completely monolayer adsorption. The above results imply that corn straw biochar is a potential adsorbent to remove PNP and Cu(II).