Adewoye T L, Ogunleye O O, Abdulkareem A S, Salawudeen T O, Tijani J O
Department of Chemical Engineering, University of Ilorin, PMB 1515 Ilorin, Kwara State, Nigeria.
Nanotechnology Research Group, Africa Centre of Excellence for Mycotoxin & Food Safety, Federal University of Technology, PMB 65 Minna, Niger State, Nigeria.
Heliyon. 2021 Jan 4;7(1):e05866. doi: 10.1016/j.heliyon.2020.e05866. eCollection 2021 Jan.
This study investigated the removal of Total Organic Carbon (TOC) from produced water by batch adsorption process using adsorbents developed from Multi-Walled Carbon Nanotubes (MWCNTs). The MWCNTs, synthesized by catalytic chemical vapour deposition method using kaolin-supported tri-metallic (iron-cobalt-nickel) catalyst were purified by HSO/HNO and then functionalized with 1-pyrenebutanoic acid N-hydroxyl succinimidyl ester (PSE). The raw, purified and functionalized MWCNTs were characterized by High Resolution Scanning Electron Microscopy (HRSEM), High Resolution Transmission Electron Microscopy (HRTEM), Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared Spectroscopy (FTIR). In the results, HRSEM/HRTEM revealed the structure, purity and also confirmed the attachment of the PSE molecule onto the nano-adsorbent(s). The BET surface areas of MWCNTs, PMWCNTs and FMWCNTs were 970.17, 869.25 and 831.80 m/g, respectively while the FTIR established the existence of surface functional groups. The functionalized MWCNTs (FMWCNTs) nano-adsorbent showed superior performance efficiency (93.6%) than the purified MWCNTs (PMWCNTs) (79.2%) as examined under the same batch adsorption condition: 0.02 g adsorbent dosage, 10-90 min contact time and 30 °C solution temperature probably, due the improved wettability resulted from incorporation of PSE. Subsequently, Central Composite Design (CCD) was applied to optimize the process parameters for the sorption of TOC onto FMWCNTs. The CCD in the response surface methodology predicted 260 mg/g adsorption capacity of FMWCNTs in the removal of TOC at the optimum condition of 49.70 min contact time, 34.81 °C solution temperature, and 0.02 g adsorbent dosage. The kinetics data were best described by pseudo-second-order model and thermodynamic parameters suggested that the process was feasible, spontaneous and exothermic. It can be inferred from the various analysis conducted that the developed FMWCNTs nano-adsorbent is effective for removal of TOC from oil-produced water and may be explored for removal of organic contaminants from other industrial wastewater.
本研究采用由多壁碳纳米管（MWCNTs）制备的吸附剂，通过间歇吸附法研究了采出水中总有机碳（TOC）的去除情况。采用高岭土负载的三金属（铁 - 钴 - 镍）催化剂，通过催化化学气相沉积法合成的MWCNTs，先用H₂SO₄/HNO₃进行纯化，然后用1 - 芘丁酸N - 羟基琥珀酰亚胺酯（PSE）进行功能化处理。通过高分辨率扫描电子显微镜（HRSEM）、高分辨率透射电子显微镜（HRTEM）、布鲁诺尔 - 埃米特 - 泰勒（BET）法和傅里叶变换红外光谱（FTIR）对原始、纯化和功能化的MWCNTs进行了表征。结果表明，HRSEM/HRTEM揭示了其结构、纯度，并证实了PSE分子附着在纳米吸附剂上。MWCNTs、PMWCNTs和FMWCNTs的BET表面积分别为970.17、869.25和831.80 m²/g，而FTIR确定了表面官能团的存在。在相同的间歇吸附条件下（吸附剂用量0.02 g、接触时间10 - 90 min、溶液温度30℃）进行检测，功能化的MWCNTs（FMWCNTs）纳米吸附剂表现出比纯化的MWCNTs（PMWCNTs）（79.2%）更高的性能效率（93.6%），这可能是由于PSE的引入提高了润湿性。随后，应用中心复合设计（CCD）优化了FMWCNTs吸附TOC的工艺参数。响应面法中的CCD预测，在接触时间49.70 min、溶液温度34.81℃和吸附剂用量0.02 g的最佳条件下，FMWCNTs对TOC的吸附容量为260 mg/g。动力学数据用伪二级模型描述最佳，热力学参数表明该过程是可行的、自发的且放热的。从所进行的各种分析可以推断，所制备的FMWCNTs纳米吸附剂对从采出水中去除TOC是有效的，并且可用于探索从其他工业废水中去除有机污染物。
