可回收和轻质氧化石墨烯/壳聚糖/京尼平海绵的合成及其对双氯芬酸、三氯生和微塑料的吸附作用。

Synthesis of recyclable and light-weight graphene oxide/chitosan/genipin sponges for the adsorption of diclofenac, triclosan, and microplastics.

机构信息

Department of Environmental Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea.

Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon 24341, Republic of Korea.

出版信息

Chemosphere. 2024 May;356:141956. doi: 10.1016/j.chemosphere.2024.141956. Epub 2024 Apr 9.

Abstract

Emerging micropollutants, such as pharmaceuticals and microplastics (MPs), have become a pressing water environmental concern. The aim of this study is to synthesize chitosan sponges using graphene oxide (GO) and genipin (GP) for the removal of pharmaceuticals (diclofenac (DCF) and triclosan (TCS)) and MPs, verify their adsorption mechanisms, evaluate the effects of temperature, pH, and salinity on their adsorption capacities, and determine their reusability. The GO/CS/GP sponge exhibited a macroporous nature (porosity = 95%, density = 32.6 mg/cm). GO and cross-linker GP enhanced the adsorption of DCF, TCS, and polystyrene (PS) MPs onto the CS sponges. The adsorption of DCF, TCS, and PS MPs involved multiple steps: surface diffusion and pore diffusion of the sponge. The adsorption isotherms demonstrated that Langmuir model was the most fitted well model to explain adsorption of TCS (q = 7.08 mg/g) and PS MPs (q = 7.42 mg/g) on GO/CS/GP sponge, while Freundlich model suited for DCF adsorption (q = 48.58 mg/g). DCF adsorption was thermodynamically spontaneous and endothermic; however, the adsorption of TCS and PS MPs was exothermic (283-313 K). The optimal pH was 5.5-7 due to the surface charge of the GO/CS/GP sponge (pH = 5.76) and ionization of DCF, TCS, and PS MPs. As the salinity increased, DCF removal efficiency drastically decreased due to the weakening of electrostatic interactions; however, TCS removal efficiency remained stable because TCS adsorption was mainly caused by hydrophobic and π-π interactions rather than electrostatic interaction. The removal of PS MPs was enhanced by the electrostatic screening effects of high Na ions. PS nanoplastics (average size = 26 nm) were removed by the GO/CS/GP sponge at a rate of 73.0%, which was better than that of PS MPs (41.5%). In addition, the GO/CS/GP sponge could be recycled over five adsorption-desorption cycles.

摘要

新兴的微污染物,如药品和微塑料(MPs),已成为紧迫的水环境问题。本研究旨在使用氧化石墨烯(GO)和京尼平(GP)合成壳聚糖海绵,用于去除药品(双氯芬酸(DCF)和三氯生(TCS))和 MPs,验证其吸附机制,评估温度、pH 值和盐度对其吸附能力的影响,并确定其可重复使用性。GO/CS/GP 海绵具有大孔性质(孔隙率为 95%,密度为 32.6mg/cm)。GO 和交联剂 GP 增强了 DCF、TCS 和聚苯乙烯(PS)MPs 吸附到 CS 海绵上。DCF、TCS 和 PS MPs 的吸附涉及多个步骤:海绵的表面扩散和孔扩散。吸附等温线表明,Langmuir 模型最适合解释 TCS(q=7.08mg/g)和 PS MPs(q=7.42mg/g)在 GO/CS/GP 海绵上的吸附,而 Freundlich 模型适合 DCF 吸附(q=48.58mg/g)。DCF 吸附是自发和吸热的;然而,TCS 和 PS MPs 的吸附是放热的(283-313K)。最佳 pH 值为 5.5-7,这是由于 GO/CS/GP 海绵的表面电荷(pH=5.76)和 DCF、TCS 和 PS MPs 的电离。随着盐度的增加,由于静电相互作用减弱,DCF 的去除效率急剧下降;然而,TCS 的去除效率保持稳定,因为 TCS 的吸附主要是由疏水和π-π相互作用引起的,而不是静电相互作用。高 Na 离子的静电屏蔽作用增强了 PS MPs 的去除。GO/CS/GP 海绵以 73.0%的速率去除 PS 纳米塑料(平均尺寸=26nm),优于 PS MPs(41.5%)。此外,GO/CS/GP 海绵可以在五个吸附-解吸循环中回收。

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