The response surface methodology has been extended to study the adsorption of malachite green dye (MG) on Indian Neem leaf powder (NLP), Azadirachta indica. The study was experimented by varying the solution concentration from 10 to 100 mg/l. The removal percentage of MG was determined by spectrophotometer at wavelength of 618 nm. Design Expert 11.0 was used as a tool to study the optimal conditions of MG adsorption (applying 2-factorial interaction model of central composite design) and evaluation of interaction effects of different operating parameters including pH, time, solute concentration, temperature and adsorbent dosage. Numerical optimization helped to identify the optimal conditions for achieving the targeted dye removal of 95.493% when the pH, time, solute concentration, temperature and adsorbent amount were set at the range of 6.868, 36.4 min, 27.899 mg/l, 308.477 K, and 4.3475 g/l respectively. The experimental results indicate that the maximum adsorption capacity of NLP depends on various operating parameter like, pH, dye concentration, particle size of adsorbents and it’s activation. It was noted that adsorption capacity of the NLP increases from 33.33 to 66.72 mg/g when it was activated with dilute HCl. The higher correlation coefficient value (R²) of Langmuir isotherm 0.996 and lower p value (0.01203) indicate the fitness of the response surface 2FI model developed. Kinetic studies displayed the suitability of pseudo second order reaction for this adsorption process. The thermodynamic study show that the sorption process is exothermic and spontaneous in nature. It was observed that the adsorbent NLP in the form of fine powder are very effective for the removal of MG from its aqueous solution. The satisfactory values of regression coefficients at different temperature, and fittings of adsorption isotherms indicate that Indian NLP is a promising adsorbent for treatment of textile dyes.

中文翻译：

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利用响应面方法从印度印em叶（印度印za）合成潜在的生物吸附剂并优化从工业废料中去除孔雀石绿染料的动力学，等温线和热力学研究

响应面方法已经扩展到研究孔雀绿染料（MG）在印度印em叶粉（NLP），印za（Azadirachta indica）上的吸附。通过将溶液浓度从10更改为100 mg / l进行了实验。通过分光光度计在618nm的波长下测定MG的去除百分比。设计专家11.0被用作研究MG吸附的最佳条件的工具（应用中心复合设计的2因子相互作用模型）和评估不同操作参数（包括pH，时间，溶质浓度，温度和吸附剂剂量）的相互作用效果。当pH，时间，溶质浓度，温度和吸附剂量分别设置为6.868、36.4 min，27.899 mg / l，308.477 K和0.868时，数值优化有助于确定实现目标染料去除率95.493％的最佳条件。分别为4.3475克/升。实验结果表明，NLP的最大吸附能力取决于各种操作参数，例如pH，染料浓度，吸附剂的粒径及其活化。注意到当用稀HCl活化时，NLP的吸附容量从33.33增加到66.72mg / g。相关系数值越高（Langmuir等温线的R ²）为0.996，较低的p值（0.01203）表明所开发的响应面2FI模型的适用性。动力学研究表明伪二级反应适合该吸附过程。热力学研究表明，吸附过程本质上是放热的，自发的。观察到细粉形式的吸附剂NLP对于从其水溶液中除去MG非常有效。在不同温度下令人满意的回归系数值，以及吸附等温线的拟合表明，印度NLP是一种有前途的吸附剂，用于处理纺织品染料。