Department of Chemistry, School of Applied Sciences, KIIT Deemed to Be University, Bhubaneswar, 24, Odisha, India.
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, 560012, India.
Chemosphere. 2022 Feb;288(Pt 2):132472. doi: 10.1016/j.chemosphere.2021.132472. Epub 2021 Oct 8.
Green synthesis of manganese oxide nanoparticles (NPs) was carried out by sol-gel method using Acacia Concinna fruit extract for removal of reactive dye. The effect of calcination temperature on its morphology was investigated. α-MnO and MnO NPs were synthesized at 400 °C and 900 °C respectively and were characterized by PXRD, SEM, TEM, FTIR, BET, Raman and TGA. As-synthesized MnO NPs were investigated for the adsorption of Reactive Blue 21 (RB-21) dye. The effect of pH, adsorbent dose, agitation speed, initial dye concentration and temperature on dye removal was explored. pH was calculated from zeta potential study showing positive surface charge below pH 3.18 resulting in electrostatic force of attraction between adsorbate and adsorbent. Both linear and non-linear regression approaches were utilised for the fitting of kinetic models and adsorption isotherms. Adsorption data follows a pseudo second order kinetics and fits well with the Freundlich isotherm model. Thermodynamic parameters such as ΔH, ΔS and ΔG were determined. The dye removal efficiency, in case of MnO NPs at pH 3.0 was obtained to be 98% whereas for MnO, no such dye adsorption was observed. The mechanism of adsorption was studied theoretically confirming π-π interaction and H-bonding between the MnO and RB dye molecules.
采用溶胶-凝胶法，以金合欢果实提取物为绿色合成试剂，制备了 MnO 纳米粒子（NPs），用于去除活性染料。研究了煅烧温度对其形态的影响。分别在 400°C 和 900°C 下合成了α-MnO 和 MnO NPs，并通过 PXRD、SEM、TEM、FTIR、BET、Raman 和 TGA 进行了表征。研究了合成的 MnO NPs 对活性蓝 21（RB-21）染料的吸附性能。考察了 pH 值、吸附剂用量、搅拌速度、初始染料浓度和温度对染料去除的影响。通过zeta 电位研究计算了 pH 值，表明在 pH 3.18 以下表面带正电荷，导致吸附质和吸附剂之间存在静电力吸引。采用线性和非线性回归方法拟合了动力学模型和吸附等温线。吸附数据符合拟二级动力学模型，并很好地符合 Freundlich 等温线模型。确定了热力学参数，如ΔH、ΔS 和ΔG。在 pH 3.0 下，MnO NPs 的染料去除效率达到 98%，而 MnO 则没有观察到这种染料吸附。从理论上研究了吸附机理，证实了 MnO 和 RB 染料分子之间的π-π相互作用和 H 键合。
