In this present study, an adsorption process was investigated to removal of Congo Red (CR) dye from aqueous solutions by using multi-walled carbon nanotubes (MWCNTs) as an adsorbent. The physico-chemical properties of MWCNTs were characterized by TEM, SEM, Raman spectroscopy and BET surface area. The response surface methodology, which is including central composite design, was used to investigate the effects of four independent parameters (initial pH of solution (5.5–11.5), initial CR concentration (15–75 mg/L), MWCNTs amount (0.05–0.25 g/L) and contact time (20–60 min)). ANOVA evaluated with Design Expert 10.0 showed that a high value of regression coefficient (R² = 0.988) a good agreement between experimental and model predicted response in addition to significance of the model. The optimum values of the independent variables giving the maximum removal efficiency (78.36%) of CR dye were obtained at the optimum adsorption conditions of initial solution pH: 5.5; initial CR concentration: 15 mg/L; MWCNTs dosage: 0.25 g/L and contact time: 59.62 min. The kinetic study illustrated that the experimental data are well defined with pseudo-second-order adsorption kinetic model. The maximum adsorption capacity (q_max) increased from 115.8 mg/g to 138.3 mg/g with the increase in temperature from 293 to 323 K. Thermodynamic parameters, ΔH (8.56 kJ/mol), ΔG (− 27.08 and − 30.73 kJ/mol) and ΔS (0.1215 kJ/mol K) were determined for the adsorption process.

在本研究中，通过使用多壁碳纳米管（MWCNT）作为吸附剂，研究了从水溶液中去除刚果红（CR）染料的吸附工艺。通过TEM，SEM，拉曼光谱和BET表面积表征了MWCNT的理化性质。包括中心复合设计在内的响应面方法用于研究四个独立参数（溶液的初始pH（5.5-11.5），初始CR浓度（15-75 mg / L），MWCNTs量（0.05-0.05）的影响。 0.25 g / L）和接触时间（20-60分钟））。使用Design Expert 10.0评估的ANOVA显示，回归系数（R ² = 0.988）除了模型的意义外，实验响应与模型预测响应之间也有很好的一致性。在初始溶液的最佳吸附条件为：pH 5.5的条件下，获得给出最大去除率（78.36％）的CR染料的自变量的最佳值。初始CR浓度：15 mg / L；MWCNTs剂量：0.25 g / L，接触时间：59.62分钟。动力学研究表明，利用伪二级吸附动力学模型可以很好地定义实验数据。随着温度从293 K增加到323 K ，最大吸附容量（q _max）从115.8 mg / g增加到138.3 mg / g。热力学参数ΔH（8.56 kJ / mol），ΔG（− 27.08和− 30.73 kJ / mol）和ΔS 确定（0.1215 kJ / mol K）的吸附过程。