The effect of adsorbent dose and initial concentration on removing the azo-anionic dyes Congo Red andtartrazine present in a synthetic aqueous solution was studied using natural cellulose (CC) and modified cationic cellulose (MCC) from coconut mesocarp. Three levels of adsorbent dosage (5, 8 and 12 mg/L) and initial concentration (40, 70 and 100 mg/L) were used. Cetyl trimethyl ammonium chloride (CTAC) was used as a modifying agent. TGA and DSC showed that the extracted cellulose was of good quality, composed mostly of cellulose with lignin and hemicellulose traces, and 8% moisture. The FTIR spectrum showed the effectiveness of the modification in the structure of the material with symmetric deformation of the C₆H₆-Cl group in 1472 cm⁻¹ present in the CTAC. It was found that decreasing the adsorbent dosage and increasing the initial concentration favored the dyes’ adsorption capacity on the two bioadsorbents. Tartrazine removals of 5.67 mg/g on CC and 19.61 mg/g on MCC were achieved, and for CR of 15.52 mg/g on CC and 19.99 with MCC with removal percentages over 97% with the quaternized biomass in all cases. The kinetic and equilibrium study was carried out to identify the mechanisms involved in the adsorption process. The Freundlich model can describe the equilibrium isotherm data of tartrazine on CC and MCC. In contrast, those of CR is defined by the Langmuir and Dubinin–Radushkevic models for CC and MCC, respectively Adsorption kinetics showed that equilibrium was reached at 30 min, with rapid adsorption in the initial minutes with the removal of about 97% of the contaminant in the first 5 min; fitting to kinetic models showed that the kinetics of tartrazine on CC was fitted by Elovich (R² = 0.756), and on MCC the Elovich (R² = 0.887) and pseudo-second-order (R² = 0.999) models. Removing CR on CC was fitted by pseudo-first-order, pseudo-second-order and Elovich models (R² > 0.98), and when using MCC, all models show a good fitting with R² = 0.99 in all cases.

中文翻译：

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改性椰子（椰子）中果皮在溶液中吸附偶氮阴离子染料的动力学和平衡研究

使用天然纤维素（CC）和改性阳离子纤维素（MCC）从椰子中果皮中研究了吸附剂量和初始浓度对去除合成水溶液中存在的偶氮阴离子染料刚果红和酒石黄的影响。使用三种水平的吸附剂剂量（5、8和12 mg / L）和初始浓度（40、70和100 mg / L）。十六烷基三甲基氯化铵（CTAC）用作改性剂。TGA和DSC显示提取的纤维素质量好，主要由具有木质素和半纤维素的痕量纤维素组成，水分含量为8％。FTIR光谱显示了在1472 cm ^-1处C ₆ H ₆ -Cl基团对称变形对材料结构进行改性的有效性。出现在CTAC中。发现降低吸附剂剂量和增加初始浓度有利于染料在两种生物吸附剂上的吸附能力。在所有情况下，CC上的酒石黄去除量分别为5.67 mg / g和MCC上的去除量为19.61 mg / g，CC上的CR为15.52 mg / g，MCC的去除量为19.99，季铵化生物量的去除率均超过97％。进行了动力学和平衡研究，以确定参与吸附过程的机理。Freundlich模型可以描述酒石黄在CC和MCC上的平衡等温线数据。相比之下，CR的值分别由Langmuir和Dubinin–Radushkevic模型的CC和MCC定义，吸附动力学表明在30分钟时达到了平衡，在最初的几分钟内迅速吸附，并在最初的5分钟内去除了约97％的污染物；拟合动力学模型表明酒石黄在CC上的动力学由Elovich（R² = 0.756），并在MCC上使用Elovich（R ² = 0.887）和伪二阶（R ² = 0.999）模型。用伪一阶，伪二阶和Elovich模型（R ² > 0.98）拟合CC上的CR ，在使用MCC时，所有模型在所有情况下均显示R ² = 0.99的良好拟合。