Jiang Xiaoling, Fan Wenqiang, Li Chunqing, Wang Yong, Bai Junbin, Yang Hongjian, Liu Xiaoli
Hebei Provincial Key Laboratory of Green Chemical Technology and High Efficient Energy Saving, Tianjin Key Laboratory of Chemical Process Safety, School of Chemical Engineering and Technology, Hebei University of Technology Tianjin 300130 China
Chengan Thermal Power Co., Ltd Tianjin 300204 China
RSC Adv. 2019 Oct 22;9(58):33949-33956. doi: 10.1039/c9ra05980f. eCollection 2019 Oct 18.
Excessive Cr(vi) emissions have been and continue to be a major contributor to heavy-metal pollution; recently, the development of a low-cost, safe and efficient method for the removal of Cr has attracted significant attention. In the present study, a two-step method involving oxalic acid reduction and modified fly ash adsorption was developed. The experimental results showed that this methodology exhibited high Cr(vi) removal efficiency under the following conditions: 1.5 g L of oxalic acid, modification of fly ash (FA) by 20 wt% KOH, a contact time of 2 h and a mass of 0.3 g of modified fly ash (MFA) at room temperature (15-25 °C). The influencing factors of the adsorbent were discussed by characterized for their elemental composition, functional groups, surface area and surface morphology. According to the characteristic parameters and , the isothermal adsorption process could be well-described by the Langmuir model. The adsorption process resembles more closely to the pseudo-second-order kinetic model. In conclusion, this two-step method of oxalic acid reduction-modified fly ash adsorption is promising for Cr(vi) removal.
过量的六价铬排放一直是并将继续是重金属污染的主要来源；最近，开发一种低成本、安全且高效的六价铬去除方法引起了广泛关注。在本研究中，开发了一种包括草酸还原和改性粉煤灰吸附的两步法。实验结果表明，该方法在以下条件下表现出高六价铬去除效率：草酸浓度为1.5 g/L，用20 wt%的氢氧化钾改性粉煤灰，接触时间为2小时，在室温（15 - 25°C）下使用0.3 g改性粉煤灰。通过对吸附剂的元素组成、官能团、表面积和表面形态进行表征，讨论了吸附剂的影响因素。根据特征参数，等温吸附过程可以用朗缪尔模型很好地描述。吸附过程更符合准二级动力学模型。总之，这种草酸还原 - 改性粉煤灰吸附的两步法在去除六价铬方面具有前景。
