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-MnO₂ 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-MnO₂ nanourchins which consists of two main stages. The initial stage includes the formation of α-MnO₂ microspheres followed by the epitaxial growth of nanoneedles on to the surface of them. The α-MnO₂ was characterised by BET, XRD, FT-IR, XPS, SEM, TEM and TGA. At 5.6, the point of zero charge of α-MnO₂ nanostructures was determined. The total pore volume and average pore radius were confirmed to be 4.751x10^-2 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-MnO₂ after dye adsorption was studied up to five cycles for its potential industrial applications.

纺织染料由于其复杂的芳族结构和差的可降解性而在水污染方面构成严重威胁。为了减小结晶紫（CV）和亚甲基蓝（MB），使用像海胆α-MnO的超声波辅助的染料吸附的毒性作用_2个纳米结构进行了研究。通过水热法在低温下合成吸附剂。测定结晶度和形态来研究α-MnO的生长机制_2个nanourchins它由两个主要阶段。初始步骤包括α-MnO的形成_2个微球，接着纳米针的外延生长以使它们的表面上。α-MnO的₂用BET，XRD，FT-IR，XPS，SEM，TEM和TGA表征。在5.6，零电荷α-的MnO的点_2级确定的纳米结构。根据BET分析，确认总孔体积和平均孔半径分别为4.751×10 ^-2 cc / g和10.99。进行批量吸附实验以研究pH，吸附剂用量，超声处理时间，初始染料浓度，温度，超声频率和功率的影响。使用几种等温线和动力学模型研究了吸附机理。采用Langmuir等温线模型和拟二阶动力学模型，观察了CV和MB在平衡状态下的吸附数据。发现了CV和MB的最大吸附容量分别为5882.3和5000 mg / g。热力学研究预测该过程对CV是放热的，对于MB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收的影响。最后，回收的α-MnO的的可重用性₂染料吸附后进行了研究最多五个循环其潜在的工业应用。