Abstract Herein, we report on the evaluation of chemically modified hyrdroxyethylcellulose for its sorption efficacy to remove Cd(II) from spiked high-hardness ground water (GW) and distilled water (DW) solutions. Hyrdroxyethylcellulose was chemically modified using adipic anhydride in the presence of DMAP as a catalyst under homogeneous reaction conditions. Hyrdroxyethylcellulose adipate (HEC-Adip) obtained was then converted to its sodium salt as HEC-Adip-Na after treating with saturated solution of NaHCO3. Structures were thoroughly characterized using FTIR, SEM, EDS and solid-state CP/MAS 13C NMR. The surface charge of the sorbent was monitored by pHZPC (pH of zero point charge). The sorption data fitted well to Langmuir isotherm and pseudo-second order kinetic model. Maximum sorption capacity of Cd(II) was calculated to be 114.94 mg g−1 and 112.35 mg g−1 from DW and GW, respectively. Thermodynamic parameters, i.e., ΔH°, ΔS° and ΔG°, were also calculated and showed negative values indicating spontaneous and exothermic nature of sorption process. In addition, the synthesized sorbent is more suitable for repeated use because it shows negligible decrease in its sorption capacity for the uptake of Cd(II) from aqueous solution after five regeneration cycles.

中文翻译：

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己二酸羟乙基纤维素钠：一种高效且可重复使用的吸附剂，用于从高硬度地下水中吸收镉

摘要 在此，我们报告了化学改性羟乙基纤维素从高硬度地下水 (GW) 和蒸馏水 (DW) 溶液中去除 Cd(II) 的吸附功效的评估。在均相反应条件下，在 DMAP 作为催化剂的存在下，使用己二酸酐对羟乙基纤维素进行化学改性。在用饱和NaHCO 3 溶液处理后，获得的己二酸羟乙基纤维素(HEC-Adip)然后转化为其钠盐作为HEC-Adip-Na。使用 FTIR、SEM、EDS 和固态 CP/MAS 13C NMR 对结构进行了彻底表征。吸附剂的表面电荷由pHZPC（零点电荷的pH）监测。吸附数据与朗缪尔等温线和伪二级动力学模型非常吻合。Cd(II) 的最大吸附容量计算为 114。分别来自 DW 和 GW 的 94 mg g-1 和 112.35 mg g-1。还计算了热力学参数，即 ΔH°、ΔS° 和 ΔG°，并显示出负值，表明吸附过程的自发和放热性质。此外，合成的吸附剂更适合重复使用，因为它在五次再生循环后从水溶液中吸收 Cd(II) 的吸附能力下降可以忽略不计。