Abstract Diglycolamine (DGA), one of the alkanolamine solvent used in natural gas sweetening unit, produces total organic acid (TOA) anions as degraded products that has detrimental effects over the operational units. In this study, calcium alginate carbon (CAC) adsorbents were used to remove TOA anions from industrial lean DGA solvent. The adsorbents were characterized by TGA, DSC, Raman, FTIR, and SEM analysis. Effects of different parameters such as the adsorption time, adsorbent dosage, and solution temperature were examined in the batch adsorption experiments. The kinetic data were best fitted to the pseudo-second-order model, highlighting chemisorption as the rate-limiting step. This was also validated using molecular modeling by predicting the intermolecular hydrogen bond formation between the organic acid anions and the calcium alginate molecules. The TOA uptake increased with the increase in the solution temperature from 49.9 mg/g at 25 °C to 72.5 mg/g at 55 °C. The CAC beads were regenerated effectively for six adsorption–desorption cycles in a fixed-bed column. The environmentally friendly CAC adsorbent exhibited significant application potential for the removal of TOA anions from lean DGA solvents.

中文翻译：

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使用海藻酸钙碳吸附剂从工业贫二甘醇胺溶剂中去除总有机酸阴离子，以及分子模型研究

摘要 二甘醇胺 (DGA) 是天然气脱硫装置中使用的一种烷醇胺溶剂，会产生总有机酸 (TOA) 阴离子作为降解产物，对操作装置产生不利影响。在这项研究中，海藻酸钙碳 (CAC) 吸附剂用于从工业贫 DGA 溶剂中去除 TOA 阴离子。通过 TGA、DSC、拉曼、FTIR 和 SEM 分析表征吸附剂。在批量吸附实验中考察了吸附时间、吸附剂用量和溶液温度等不同参数的影响。动力学数据最适合伪二级模型，突出化学吸附作为限速步骤。这也通过预测有机酸阴离子和藻酸钙分子之间的分子间氢键形成，使用分子模型进行了验证。TOA 吸收随着溶液温度的升高而增加，从 25 °C 时的 49.9 mg/g 增加到 55 °C 时的 72.5 mg/g。CAC 珠在固定床柱中有效地再生了六个吸附-解吸循环。环保的 CAC 吸附剂在去除贫 DGA 溶剂中的 TOA 阴离子方面具有显着的应用潜力。