Qiu Ruifang, Cheng Fangqin
Institute of Resources & Environment Engineering, Shanxi University, State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Shanxi Innovation Hub of Resource Recycling and Ecological Engineering, Taiyuan 030006, China E-mail:
Water Sci Technol. 2016;74(2):524-34. doi: 10.2166/wst.2016.235.
We developed a new calcination method to convert coal gangue (CG), a common waste generated from coal production process, into a modified form, which could be used as an adsorbent to remove Mn(2+) from aqueous solution. Sodium tetraborate (Na2B4O7·10H2O) was added into the CG calcination process as an additive, and the concentrations of Na2B4O7·10H2O were optimized along with the calcination temperature to obtain the best adsorbent capacity of modified coal gangue (MCG). We applied multiple analytical methods such as scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller analysis to characterize the MCG. The results showed it had a smaller particle size and a larger specific surface area and pore volume after modification. It also indicated that the phase of CG transformed from kaolinite to metakaolinite after calcination. Moreover, a new substance was generated with two new peaks at 1,632 cm(-1) and 799 cm(-1). The Mn(2+) absorption capacity of MCG was evaluated using a series of experiments with different adsorbent doses, pH values and initial Mn(2+) concentrations during the adsorption process. We found that Mn(2+) adsorbent capacity of MCG increased by more than seven-fold compared to that of CG. The Langmuir isotherm model and the pseudo-second-order kinetic model provided the best fit to the adsorption processes.
我们开发了一种新的煅烧方法，将煤矸石（CG）（煤炭生产过程中产生的一种常见废弃物）转化为一种改性形式，可用作从水溶液中去除Mn(2+)的吸附剂。在CG煅烧过程中加入四硼酸钠（Na2B4O7·10H2O）作为添加剂，并优化Na2B4O7·10H2O的浓度以及煅烧温度，以获得改性煤矸石（MCG）的最佳吸附能力。我们应用了多种分析方法，如扫描电子显微镜、X射线衍射、傅里叶变换红外光谱和布鲁诺尔-埃米特-泰勒分析来表征MCG。结果表明，改性后其粒径更小，比表面积和孔体积更大。这也表明CG在煅烧后从高岭石相转变为偏高岭石相。此外，还生成了一种新物质，在1632 cm(-1)和799 cm(-1)处出现两个新峰。在吸附过程中，通过一系列不同吸附剂剂量、pH值和初始Mn(2+)浓度的实验，对MCG对Mn(2+)的吸附能力进行了评估。我们发现，与CG相比，MCG对Mn(2+)的吸附能力提高了七倍多。朗缪尔等温线模型和伪二级动力学模型最能拟合吸附过程。
