Department of Civil and Environmental Engineering, National University of Singapore, Singapore.
Department of Civil and Environmental Engineering, National University of Singapore, Singapore.
Chemosphere. 2021 Sep;278:130361. doi: 10.1016/j.chemosphere.2021.130361. Epub 2021 Mar 24.
We developed biochar by pyrolysis of pinewood wastes at different temperatures and investigated its potential to nitrate and phosphate from single and binary solutions. An in-depth characterization of biochar was carried out to study its physical, surface morphological and chemical characteristics using X-ray diffraction, Fourier transform infrared and scanning electron microscopy analyses. The impact of pyrolysis temperatures (300-600 °C) on the biochar yield, the biochar's elemental composition, and its adsorption characteristics was examined. Biochar produced at 600 °C showed a maximum uptake for both nitrate and phosphate due to its high C content (63.8%), pore volume (0.201 cm/g), surface area (204.2 m/g) and reduced acidic binding groups. The influence of pH, initial solute concentrations, contact time on the removal of a single solute at a time by biochar was examined. Results revealed that pinewood-derived biochar had its maximum performance at pH 2, with predicted equilibrium uptakes of 20.5 and 4.20 mg/g for phosphate and nitrate, respectively at initial solute concentrations of 60 mg/L within 360 min. The single solute isotherm was studied using the Freundlich, Langmuir and Toth models, and kinetics was described using the pseudo-first and -second order models. While using dual-solutes, biochar showed preference towards phosphate as confirmed by high affinity factor. The dual-solute kinetic experiments showed that around 95% of phosphate was removed within 45 min, whereas it took 240 min to achieve 95% total nitrate removal from the mixture. Thus, the biochar removes phosphate preferentially with high selectivity as compared to nitrate.
我们通过在不同温度下热解松木废料来制备生物炭，并研究了其从单组分和双组分溶液中去除硝酸盐和磷酸盐的潜力。通过 X 射线衍射、傅里叶变换红外和扫描电子显微镜分析对生物炭进行了深入的特性研究，以研究其物理、表面形貌和化学特性。研究了热解温度（300-600°C）对生物炭产率、生物炭元素组成及其吸附特性的影响。由于 600°C 下生物炭的 C 含量（63.8%）、孔体积（0.201cm/g）、表面积（204.2m/g）和酸性结合基团减少，其对硝酸盐和磷酸盐的吸附量最大。考察了 pH 值、初始溶质浓度、接触时间对一次同时去除单一溶质的影响。结果表明，在 pH 值为 2 时，松木衍生生物炭的性能最佳，在初始溶质浓度为 60mg/L 时，360min 内对磷酸盐和硝酸盐的预测平衡吸附量分别为 20.5 和 4.20mg/g。通过 Freundlich、Langmuir 和 Toth 模型研究了单溶质等温线，通过拟一级和拟二级模型描述了动力学。在使用双组分时，通过高亲和因子证实了生物炭对磷酸盐的优先吸附。双组分动力学实验表明，在 45min 内可去除约 95%的磷酸盐，而从混合物中去除 95%的硝酸盐则需要 240min。因此，与硝酸盐相比，生物炭对磷酸盐具有优先去除的高选择性。
