镁改性凹凸棒土对沼液中氮磷的吸附研究

Adsorption of Nitrogen and Phosphorus in Biogas Slurry by Magnesium Modified Attapulgite

利用氧化镁改性凹凸棒土为吸附剂,研究其对沼液中氮磷的吸附特性与吸附机理。研究结果显示:投加量为2.5g/L,pH=9时氮磷吸附量最大,Ca^(2+)对磷的去除有促进作用,共存离子会抑制氨氮的去除,氮磷最大吸附量可分别达到37.83mg/g、70.58mg/g。准二级动力学与Langmuir等温模型可以很好地描述吸附剂对氮磷的吸附过程。形态提取与表征分析表明,氮磷去除机理包括静电吸引、离子交换、配位作用、化学沉淀等,其中磷酸铵镁化学沉淀在氮磷去除中起到关键作用。

Attapulgite modified by magnesium oxide was used as adsorbent to study the adsorption characteristics and mechanism of nitrogen and phosphorus in biogas slurry.The results show that when the dosage is 2.5g/L and pH=9,the adsorption capacity of nitrogen and phosphorus reaches the maximum.Ca^(2+) promotes the removal of phosphorus,while coexisting ions inhibit the removal of ammonia nitrogen.The maximum adsorption capacity of nitrogen and phosphorus reaches 37.83mg/g and 70.58mg/g,respectively.Quasi-second-order kinetics and Langmuir isothermal model can be well describe the adsorption process of nitrogen and phosphorus.Morphological extraction and characterization analysis show that the removal mechanisms of nitrogen and phosphorus include electrostatic attraction,ion exchange,coordination and chemical precipitation,among which chemical precipitation of magnesium ammonium phosphate plays a key role in the removal of nitrogen and phosphorus.