In order to remove low concentration of phosphorus in wastewater and realize resource utilization of reed, reed biochar(RB) was prepared using reed and then modified by ferric chloride, and the adsorption behavior of low concentration phosphorus was investigated. The results showed that the iron content of modified reed biochar(MRB) was 11.98 mg·g-1, which was 44.7 times that of RB; pHpzc of the MRB was 7.49, and the adsorption effect was the best when the solution pH was 7.0; at the initial concentration of 4.0 mg·L-1 and temperature of 298K, the adsorption capacity of MRB was 0.658 mg·g-1, which was 34.6 times that of RB. The adsorption isotherms at different temperatures were well fitted to Langmiur equation, which indicated the adsorption was monolayer adsorption, and increasing temperature was favorable for adsorption. ΔGθ<0, ΔHθ>0 and ΔSθ>0 indicated that the adsorption was a spontaneous, entropy increasing and endothermic process. The kinetic experimental data of the adsorption fitted well to the pseudo-second-order equation, the initial adsorption rate increased with the increasing initial concentration of solution, and the adsorption was mainly controlled by intraparticle diffusion. The research will provide basic data for application of MRB in deep removal of low concentration phosphorus from sewage treatment plant and water body.
Keywords: adsorption; ferric chloride; low concentration phosphorus; modification; modified reed biochar.