Jiangsu Key Laboratory for Eco-Agricultural Biotechnology around Hongze Lake/Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huai'an, 223300, China E-mail:
School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an, 223300, China.
Water Sci Technol. 2020 May;81(10):2270-2280. doi: 10.2166/wst.2020.290.
It is of great significance to remove Cr(VI) from water as a result of its high toxicity. Biochar from corn straw was modified by different acids (HNO, HSO and HPO) to remove Cr(VI) from aqueous solution. To estimate the removal mechanisms of Cr(VI) by the acid-modified biochars, batch experiments were performed in the light of contact time, Cr(VI) concentration, and pH, and the characteristics of acid-modified biochars before and after Cr(VI) adsorption were investigated by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of Cr(VI) by acid-modified biochars were consistent with the pseudo-second-order model, and the adsorption isotherm obeyed the Freundlich model. Furthermore, the acid- modified biochars could supply more oxygen-containing functional groups (-COOH and -OH) as electron donor (e) and hydrogen ion (H) to enhance the reduction of Cr(VI) to Cr(III), resulting in enhanced removal of Cr(VI). HNO-modified biochar exhibited the highest removal efficiency of Cr(VI). In general, the acid modifition of biochar was an effective method to increase the removal of Cr(VI).
由于六价铬（Cr(VI)）毒性很高，因此将其从水中去除具有重要意义。本研究采用不同酸（HNO、HSO 和 HPO）对玉米秸秆生物炭进行改性，以去除水溶液中的 Cr(VI)。为了评估酸改性生物炭去除 Cr(VI)的机制，通过接触时间、Cr(VI)浓度和 pH 值进行了批量实验，并通过傅里叶变换红外光谱（FTIR）和 X 射线光电子能谱（XPS）研究了 Cr(VI)吸附前后酸改性生物炭的特性。Cr(VI)在酸改性生物炭上的吸附动力学符合准二级模型，吸附等温线符合 Freundlich 模型。此外，酸改性生物炭可以提供更多的含氧官能团（-COOH 和-OH）作为电子供体（e）和氢离子（H），以增强 Cr(VI)的还原为 Cr(III)，从而提高 Cr(VI)的去除率。HNO 改性生物炭对 Cr(VI)的去除效率最高。总的来说，生物炭的酸改性是增加 Cr(VI)去除率的有效方法。
