Rout Dibya Ranjan, Jena Hara Mohan
Department of Chemical Engineering, National Institute of Technology, Rourkela, 769008, Orissa, India.
Environ Sci Pollut Res Int. 2022 May;29(21):32105-32119. doi: 10.1007/s11356-021-17944-y. Epub 2022 Jan 11.
This work focuses on the batch adsorption study of phenol from an aqueous solution. Here, reduced graphene oxide (RGO) is used as an adsorbent. To synthesize reduced graphene oxide from graphene oxide, hydrazine monohydrate is used as a reducing agent. The synthesized samples were characterized using SEM, EDX, XRD, FTIR, BET surface area analyzer, RAMAN spectra, and zeta potential. The effects of solution pH, adsorption time, temperature, adsorbent dosage, and initial phenol concentration on adsorption characteristics were systematically studied. The optimized adsorption parameters were 0.4 g/L of adsorbent dosage, pH of 8.0, adsorption time 75 min, and temperature of 30 °C. The adsorption isotherm data follows the Langmuir isotherm model, and the maximum adsorption capacity (q) was 602.41 mg/g. The kinetic data of the adsorption follows the pseudo-second-order kinetic model. The Boyd model confirmed that film diffusion was the rate-limiting step in the adsorption process. The thermodynamic study of phenol adsorption using RGO confirms the endothermic nature of the process. The negative values of Gibb's free energy (ΔG) confirm that the process was spontaneous. The positive value of change in entropy (ΔS = 346.885 J/K) suggests that the randomness was increased at the solution/solid interface. The most important feature of this adsorbent was it could be easily and efficiently regenerated from phenol-loaded adsorbent with a negligible effect on removal efficiency. This study evidenced an effective use of RGO as an adsorbent for phenol removal.
本研究聚焦于从水溶液中批量吸附苯酚。在此，还原氧化石墨烯（RGO）被用作吸附剂。为了从氧化石墨烯合成还原氧化石墨烯，使用水合肼作为还原剂。合成的样品通过扫描电子显微镜（SEM）、能量散射X射线谱（EDX）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、比表面积分析仪、拉曼光谱和zeta电位进行表征。系统研究了溶液pH值、吸附时间、温度、吸附剂用量和初始苯酚浓度对吸附特性的影响。优化后的吸附参数为吸附剂用量0.4 g/L、pH值8.0、吸附时间75分钟和温度30℃。吸附等温线数据符合朗缪尔等温线模型，最大吸附容量（q）为602.41 mg/g。吸附动力学数据符合准二级动力学模型。博伊德模型证实膜扩散是吸附过程中的限速步骤。使用RGO对苯酚吸附的热力学研究证实了该过程的吸热性质。吉布斯自由能（ΔG）的负值证实该过程是自发的。熵变的正值（ΔS = 346.885 J/K）表明溶液/固体界面的随机性增加。这种吸附剂最重要的特点是它可以很容易且高效地从负载苯酚的吸附剂中再生，对去除效率的影响可忽略不计。本研究证明了RGO作为一种去除苯酚的吸附剂的有效应用。
