Abstract

Lotus leaf powder (LLP) was chemically modified with dimethylamine (DMA) to achieve a tertiary amine type powder, named DMA-LLP, and used as an adsorbent for the removal of Reactive Red 195 (RR 195) from the aqueous medium. DMA-LLP was characterized using field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), point of zero charge (pH_PZC), and fourier transform infrared (FTIR) spectroscopy. The kinetic data exhibited a good correlation coefficient (R² > 0.9916) for the pseudo-second-order model. To evaluate the equilibrium data at different temperatures, the non-linear Langmuir and Freundlich isothermal models were used. The Langmuir model best described the equilibrium data (R² > 0.9931). The maximum adsorption uptake from the Langmuir model, q_max, was 131.5 mg/g (pH = 2.0, C_o = 300 mg/L, dosage = 0.03 g/30 mL, and T = 298 K). The pH_PZC of DMA-LLP was found to be 5.5. The obtained thermodynamic parameters demonstrated the spontaneous and endothermic nature of the adsorption. The regeneration findings indicate that DMA-LLP could be used up to five times, with maximum removal of 72% achieved after the fifth cycle. Thus, we conclude that the DMA-LLP was an efficient adsorbent for removing RR 195 from the aqueous environment.

NOVELTY STATEMENT

In the modern era, dyes are inevitable and their surging usage leads to colossal contamination of aqueous streams, thereby threatening both the land and aquatic species. One among such dye is anionic Reactive Red 195 (RR 195), and traceable even at minute concentrations of aqueous streams, posing a severe threat to living species. Moreover, RR 195 is highly recalcitrant offering resistance to biodegradation due to the presence of an azo (–N=N–) group within its structure. Thus, there is a definite need to address the issue of eliminating RR 195 from industrial wastewater effluents. In lieu of this, the primitive objective of this study is to test the effectiveness of the natural adsorbent lotus leaf (Nelumbo nucifera) for the selective sorption of RR 195 from the aqueous stream. Although ample literature is available on the direct utilization of lotus leaf as adsorbent, yet no study was performed on the chemical modification (dimethylamine) of the aforementioned adsorbent. Hence, an attempt has been made in this direction to add a new sorbent into the adsorbents database.

中文翻译：

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使用经二甲胺化学改性的莲花 (Nelumbo nucifera) 叶粉从水介质中吸附活性红 195：表征、等温线、动力学、热力学和机理评估

摘要

荷叶粉 (LLP) 用二甲胺 (DMA) 进行化学改性，得到叔胺型粉末，命名为 DMA-LLP，并用作吸附剂从水介质中去除活性红 195 (RR 195)。DMA-LLP 使用场发射扫描电子显微镜 (FE-SEM)、能量色散 X 射线光谱 (EDX)、Brunauer-Emmett-Teller (BET)、零电荷点 (pH _PZC ) 和傅里叶变换红外进行表征(FTIR) 光谱学。动力学数据表现出良好的伪二级模型相关系数（ R ^{2 > 0.9916）。}为了评估不同温度下的平衡数据，使用了非线性 Langmuir 和 Freundlich 等温模型。Langmuir 模型最能描述平衡数据（R² > 0.9931)。Langmuir 模型的最大吸附量q _max为 131.5 mg/g（pH = 2.0， C _o = 300 mg/L，剂量 = 0.03 g/30 mL， T  = 298 K）。发现 DMA-LLP的 pH _PZC为 5.5。获得的热力学参数证明了吸附的自发和吸热性质。再生结果表明 DMA-LLP 最多可使用五次，在第五次循环后最大去除率达到 72%。因此，我们得出结论，DMA-LLP 是一种从水环境中去除 RR 195 的有效吸附剂。

新颖性声明

在现代，染料是不可避免的，其激增的使用导致水流的巨大污染，从而威胁到土地和水生物种。其中一种染料是阴离子活性红 195 (RR 195)，即使在微量水流浓度下也可追踪，对生物物种构成严重威胁。此外，由于在其结构中存在偶氮 (-N=N-) 基团，RR 195 具有很强的抗生物降解性。因此，明确需要解决从工业废水排放物中消除 RR 195 的问题。取而代之的是，本研究的原始目的是测试天然吸附荷叶（Nelumbo nucifera) 用于从水流中选择性吸附 RR 195。尽管有大量关于直接利用荷叶作为吸附剂的文献，但尚未对上述吸附剂的化学改性（二甲胺）进行研究。因此，已经尝试在这个方向上将新的吸附剂添加到吸附剂数据库中。