Wang Bin-Bin, Lin Jing-Dong, Wan Shun-Li, He Feng
College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Huan Jing Ke Xue. 2017 Jul 8;38(7):2859-2867. doi: 10.13227/j.hjkx.201611129.
A novel composite material MgO-biochar (MgO-BC) with the peanut shells as the precursors was successfully fabricated by loading magnesium oxide (MgO) on the surface of biochar (BC) at high temperature and in oxygen-limited atmosphere. The adsorption characteristics of the resultant adsorbent toward phosphate from aqueous solution were investigated by evaluating the influences of pH, contact time and coexisting ions. The results showed that the best phosphate adsorption onto MgO-BC happened in the pH range of 7-9, and strong acidic or basic media was unfavorable to the phosphate adsorption. Phosphate adsorption process could reach equilibrium within 540 min, and the kinetics curve could be well fitted by both pseudo-first and pseudo-second models. The related coefficients were 97.3% and 99.0%. MgO-BC exhibited highly selective capacity toward phosphate in the presence of competing Cl, HCO and NO at 10 times higher concentration than the phosphate concentration. In addition, phosphate adsorption onto MgO-BC could be described satisfactorily by Langmuir model with a fitting coefficient of higher than 99%, and the maximal adsorption capacity calculated by Langmuir equation was 138.07 mg·g. The adsorption capacity of phosphate by MgO-BC was much higher than the unmodified BC and other biochar-based sorbents. Furthermore, the composite material after the adsorption of phosphate could also be used as a fertilizer into the soil. It achieved the reuse of the discarded phosphate. All the results validated that MgO-BC has a wide application prospect for the phosphate cleanup from the actual wastewater.
以花生壳为前驱体，通过在高温和限氧气氛下将氧化镁（MgO）负载在生物炭（BC）表面，成功制备了一种新型复合材料MgO-生物炭（MgO-BC）。通过评估pH值、接触时间和共存离子的影响，研究了所得吸附剂对水溶液中磷酸盐的吸附特性。结果表明，MgO-BC对磷酸盐的最佳吸附发生在pH值为7-9的范围内，强酸性或强碱性介质不利于磷酸盐的吸附。磷酸盐吸附过程可在540分钟内达到平衡，动力学曲线可用伪一级和伪二级模型很好地拟合。相关系数分别为97.3%和99.0%。在Cl、HCO和NO浓度比磷酸盐浓度高10倍的竞争存在下，MgO-BC对磷酸盐表现出高度选择性。此外，MgO-BC对磷酸盐的吸附可用Langmuir模型满意地描述，拟合系数高于99%，通过Langmuir方程计算的最大吸附容量为138.07 mg·g。MgO-BC对磷酸盐的吸附容量远高于未改性的BC和其他生物炭基吸附剂。此外，吸附磷酸盐后的复合材料还可作为肥料施入土壤。实现了废弃磷酸盐的再利用。所有结果验证了MgO-BC在实际废水磷酸盐净化方面具有广阔的应用前景。
