Alikhani Mina, Khoshkalam Ehsan, Sadeghi Jalal, Bulgariu Laura, Eshghi Hossein
Department of Chemistry, Payame Noor University Tehran Iran.
Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad (FUM) Mashhad Iran
RSC Adv. 2024 Aug 5;14(34):24534-24547. doi: 10.1039/d4ra02428a.
The primary goal of this study is to examine PO adsorption from aqueous solutions using zinc-doped carbon dots (Zn-N-CDs) as a new adsorbent and cost-effective technique. Zn-N-CDs were produced through a hydrothermal process and subsequently identified using various techniques. The effect of reaction time, temperature, pH, ionic strength, adsorbent dosage, initial PO concentration, and anion competition (NO , Cl, HCO , and SO ) on PO adsorption using Zn-N-CDs were investigated. The characterization results depicted that Zn-N-CDs have a spherical structure without obvious aggregation and revealed the amorphous nature of carbon dots with many pores. Zn-N-CDs had a high affinity for adsorbing PO , reaching equilibrium within 5 minutes. While PO adsorption reduced with an increase in temperature, it increased with pH and ionic strength. The optimal conditions for PO adsorption were determined to be pH 8, 100 mM KCl as an ionic strength, and 5 g L of Zn-N-CDs. The presence of SO and HCO as competing anions slightly decreased PO adsorption. Thermodynamic studies revealed that PO adsorption onto Zn-N-CDs was endothermic, spontaneous, and disordered, as evidenced by Δ° < 0, Δ° > 0, and Δ° > 0. The experimental data fit well with a pseudo-second-order kinetic model ( = 0.999) and the Freundlich isotherm model ( = 0.9754), signifying that PO adsorption onto Zn-N-CDs occurs through multi-layer and chemi-sorption mechanisms. Overall, Zn-N-CDs indicated a great capability to adsorb high concentrations of PO across a wide range of pH values, indicating their potential for environmental remediation.
本研究的主要目标是使用锌掺杂碳点（Zn-N-CDs）作为一种新型吸附剂和具有成本效益的技术，来研究从水溶液中吸附磷酸根（PO）的情况。Zn-N-CDs通过水热法制备，随后使用各种技术进行鉴定。研究了反应时间、温度、pH值、离子强度、吸附剂用量、初始PO浓度以及阴离子竞争（NO、Cl、HCO和SO）对使用Zn-N-CDs吸附PO的影响。表征结果表明，Zn-N-CDs具有球形结构且无明显聚集，揭示了具有许多孔隙的碳点的非晶性质。Zn-N-CDs对吸附PO具有高亲和力，在5分钟内达到平衡。虽然PO吸附量随温度升高而降低，但随pH值和离子强度增加而增加。确定PO吸附的最佳条件为pH 8、离子强度为100 mM KCl以及Zn-N-CDs用量为5 g/L。作为竞争阴离子的SO和HCO的存在略微降低了PO吸附量。热力学研究表明，PO吸附到Zn-N-CDs上是吸热、自发且无序的，Δ°<0、Δ°>0和Δ°>0证明了这一点。实验数据与伪二级动力学模型（=0.999）和Freundlich等温线模型（=0.9754）拟合良好，表明PO吸附到Zn-N-CDs上是通过多层和化学吸附机制发生的。总体而言，Zn-N-CDs表明在广泛的pH值范围内具有吸附高浓度PO的强大能力，表明其在环境修复方面的潜力。
