Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, China; Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Hung Hom, Kowloon, Hong Kong.
Chemosphere. 2021 May;270:129423. doi: 10.1016/j.chemosphere.2020.129423. Epub 2020 Dec 30.
Adsorption methods have been widely used in wastewater treatment due to its high removal efficiency, easy operation and handling, economic efficiency and little secondary pollution to the environment. In this paper, a high-iron containing incineration sewage sludge ash (ISSA) was modified by combined acid leaching and precipitation processes to improve its adsorption capacity of As(V). The effects of pH, time, temperature and ionic strength on the adsorption of As(V) were investigated by batch adsorption experiments. The results indicated that iron (mainly present as hematite) in the ISSA was rearranged to Fe(SO)OH. The modified ISSA showed an excellent adsorption potential for As(V) under acidic conditions and the adsorption capacity was around 9 times of the unmodified ISSA at pH 2-3. The adsorption process was fast during the first 2 h and reached an equilibrium at around 6 h. The Freundlich model could well fit the adsorption isotherm data, the presence of NO and Cl had a negligible influence on the As(V) removal by the modified ISSA, while PO and SO could significantly suppress As(V) removal via competitive adsorption. After 3 cycles of regeneration, the modified ISSA still showed a satisfying adsorption capacity. As(V) was removed by the modified ISSA mainly through ligand exchange reaction with hydroxyl oxygen (OH-) to form inner-sphere complexes. Therefore, the modified ISSA can be a promising material for As(V) removal from wastewater in particular due to the waste recycling potential.
吸附法因其去除效率高、操作和处理简便、经济效益高、对环境的二次污染小等优点，在废水处理中得到了广泛的应用。本文采用联合酸浸和沉淀工艺对高铁含量的焚烧污水污泥灰（ISSA）进行改性，以提高其对 As(V)的吸附能力。通过批量吸附实验考察了 pH 值、时间、温度和离子强度对 As(V)吸附的影响。结果表明，ISSA 中的铁（主要以赤铁矿形式存在）被重新排列为 Fe(SO)OH。改性 ISSA 在酸性条件下对 As(V)具有优异的吸附潜力，在 pH 2-3 时的吸附容量约为未改性 ISSA 的 9 倍。吸附过程在前 2 h 内较快，约 6 h 达到平衡。Freundlich 模型可以很好地拟合吸附等温线数据，NO 和 Cl 的存在对改性 ISSA 去除 As(V)的影响可以忽略不计，而 PO 和 SO 可以通过竞争吸附显著抑制 As(V)的去除。经过 3 次再生循环，改性 ISSA 仍表现出令人满意的吸附容量。As(V)主要通过与羟基氧（OH-）的配体交换反应被改性 ISSA 去除，形成内球络合物。因此，由于废物再利用的潜力，改性 ISSA 有望成为去除废水中 As(V)的一种有前途的材料。
