School of Civil and Chemical Engineering, Vellore Institute of Technology, Vellore Campus, Vellore 632014, India.
School of Civil and Chemical Engineering, Vellore Institute of Technology, Vellore Campus, Vellore 632014, India.
Ultrason Sonochem. 2018 Dec;49:175-189. doi: 10.1016/j.ultsonch.2018.07.045. Epub 2018 Aug 3.
Textile dyes pose a serious threat in terms of water pollution due to its complex aromatic structures and poor degradability. In order to reduce the toxic effects of Crystal Violet (CV) and Methylene Blue (MB), an ultrasonic-assisted dye adsorption using urchin like α-MnO nanostructures was studied. The adsorbent was synthesised by hydrothermal method at low-temperature. The crystallinity and morphology were determined to investigate the growth mechanism of α-MnO nanourchins which consists of two main stages. The initial stage includes the formation of α-MnO microspheres followed by the epitaxial growth of nanoneedles on to the surface of them. The α-MnO was characterised by BET, XRD, FT-IR, XPS, SEM, TEM and TGA. At 5.6, the point of zero charge of α-MnO nanostructures was determined. The total pore volume and average pore radius were confirmed to be 4.751 × 10 cc/g and 10.99 Å respectively from the BET analysis. Batch adsorption experiments were performed to investigate the effect of pH, adsorbent dosage, sonication time, initial dye concentration, temperature, ultrasonic frequency and power. The adsorption mechanism was studied using several isotherm and kinetic models. The adsorption data of CV and MB at equilibrium was observed to adopt the Langmuir isotherm model and pseudo-second order kinetic model. The maximum adsorption capacities for CV and MB were found to be 5882.3 and 5000 mg/g respectively. The thermodynamic study predicted that the process was exothermic for CV and endothermic for MB. The effects of competitive ions, ionic strength and humic acid on the uptake of both the dyes were also investigated. And finally, the reusability of recovered α-MnO after dye adsorption was studied up to five cycles for its potential industrial applications.
纺织染料因其复杂的芳香结构和较差的可降解性，对水污染构成了严重威胁。为了降低结晶紫（CV）和亚甲蓝（MB）的毒性作用，研究了一种使用具有刺猬状α-MnO 纳米结构的超声辅助染料吸附方法。该吸附剂是通过低温水热法合成的。通过结晶度和形态的测定，研究了α-MnO 纳米刺猬的生长机制，该机制包括两个主要阶段。初始阶段包括α-MnO 微球的形成，随后在其表面外延生长纳米针。通过 BET、XRD、FT-IR、XPS、SEM、TEM 和 TGA 对α-MnO 进行了表征。在 pH 值为 5.6 时，确定了α-MnO 纳米结构的零电荷点。通过 BET 分析，确定总孔体积和平均孔径分别为 4.751×10-3cc/g 和 10.99Å。进行了批量吸附实验，以研究 pH 值、吸附剂用量、超声时间、初始染料浓度、温度、超声频率和功率对吸附效果的影响。通过几种吸附等温线和动力学模型研究了吸附机制。观察到 CV 和 MB 在平衡时的吸附数据采用 Langmuir 等温线模型和拟二级动力学模型。发现 CV 和 MB 的最大吸附容量分别为 5882.3 和 5000mg/g。热力学研究预测，CV 的过程是放热的，而 MB 的过程是吸热的。还研究了竞争离子、离子强度和腐殖酸对两种染料吸附的影响。最后，研究了染料吸附后回收的α-MnO 的可重复使用性，以评估其在工业应用中的潜力，最多可重复使用五轮。
