污泥生物炭制备及其对磷的吸附性能研究

以污水污泥、粉煤灰为原料,以质量分数为30%的氯化锌溶液为活化剂,在不同温度下煅烧制备污泥生物炭,用于处理含磷废水。通过单因素静态吸附实验探讨了污泥生物炭对磷的去除效果,并探究了其吸附机理。结果表明：300 ℃制备的污泥生物炭具有较好的除磷效果;扫描电镜（SEM）、比表面分析仪、傅里叶红外光谱仪（FT-IR）对原料和污泥生物炭表征结果显示,污泥生物炭煅烧前后的形貌及表面基团发生了显著改变,煅烧后样品的表面产生了较多微小空隙,比表面积增大,最高可达5.51 m²/g;在磷初始质量浓度为50 mg/L、吸附剂用量为16 g/L条件下,吸附在90 min达到平衡,磷的去除率高达93.73%;吸附过程符合准二级动力学方程及Freundlich等温吸附模型,最大饱和吸附量为9.615 mg/g;整个吸附过程ΔG⁰<0、ΔH⁰<0,是自发进行的放热过程;吸附过程除物理吸附外,同时涉及磷酸盐与吸附剂—OH或C—O共价键发生电子对配位作用,为物理-化学复合吸附;吸附剂第5次吸附为首次吸附量的85.74%,表现出较好的再生性能。

Study on preparation of sludge biochar and its adsorption performance for phosphorus

Sewage sludge and fly ash were used as raw materials and zinc chloride solution with mass fraction of 30% was used as activator to prepare sludge biochar calcined at different temperatures,the sludge biochar was used to treat phosphorus containing wastewater.The effect of sludge biochar on phosphorus removal was investigated through single factor static adsorp-tion experiment and its adsorption mechanism was explored.The results showed that the sludge biochar prepared at 300 ℃ had better phosphorus removal effect.The characterization analysis of raw materials and sludge biochar by scanning electron microscopy（SEM）,specific surface analyzer and fourier infrared spectroscopy（FT-IR） showed that the morphology and surface groups of sludge biochar were significantly changed after calcination,there were many microvoids on the surface of the sample after calcination,and the specific surface area increased to 5.51 m²/g;under the condition of initial mass concent-ration of phosphorus 50 mg/L and the amount of adsorbent 16 g/L,the adsorption reached equilibrium in 90 minutes,and the removal rate of phosphorus was 93.73%;the adsorption process conformed to the quasi second order kinetic equation and the freundlich isotherm adsorption model,and the maximum saturated adsorption capacity was 9.615 mg/g;the whole adsorption process Δ G ⁰<0 and ΔH⁰<0,which was a spontaneous exothermic process.In addition to physical adsorption,the adsorption process also involves electron pair coordination between phosphate and—OH or C—O covalent bond of adsorbent,which was a physical-chemical composite adsorption; the fifth adsorption capacity of the adsorbent was 85.74% of the first adsorption capacity,showing good regeneration performance.