Journal Article

Effects of low molecular weight organic acids on adsorption of quinclorac by sepiolite

Zhou, Xuguo, Deng, Yaocheng, Gong, Daoxin, Yang, Lihua, Luo, Haifeng, Jiang, Fangzhou

2021

Overview

The effects of low molecular weight organic acids (LMWOAs) on the adsorption of quinclorac by sepiolite were investigated using laboratory batch technique. Experiments were conducted with two natural sepiolite samples with different crystal structures and chemical compositions and high-purity sepiolite. The LMWOAs used were acetic, oxalic, and citric acid. And the adsorption mechanism was characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Our analysis revealed that adsorption of quinclorac on α-sepiolite and β-sepiolite was inhibited in the presence of 4 mmol L −1 LMWOAs, whereas LMWOAs stimulated the adsorption of quinclorac in the high-purity sepiolite. Inhibition or stimulation varied across the different types of organic acids. The adsorption isotherms in the presence of 4 mmol L −1 LMWOAs were better explained by Freundlich and linear model. The effect of organic acid concentrations (0–32 mmol L −1 ) on the adsorption of quinclorac by the three sepiolite samples varies greatly depending on the type of organic acid and the property of sepiolite. FTIR, XRD, and XPS analyses showed that LMWOAs bound strongly to the Si–O bond structure, and Si–O-quinclorac-acetic acid (oxalic acid or citric acid) was formed on the surface of β-sepiolite. The adsorption of quinclorac by β-sepiolite was via hydrogen bond, complexation reactions, and charge transfer in the presence of LMWOAs. These results indicate that LMWOAs affect quinclorac adsorption through various interactions involving competition, electrostatic attraction, bridging action, and hydrogen bonding.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Acetic acid / Acids / Adsorption / Aquatic Pollution / Atmospheric Protection/Air Quality Control/Air Pollution / Charge transfer / Chemical composition / Citric acid / Crystal structure / Earth and Environmental Science / Ecotoxicology / electrostatic interactions / Electrostatic properties / Environment / Environmental Chemistry / Environmental Health / Environmental science / Fourier analysis / Fourier transform infrared spectroscopy / Fourier transforms / hydrogen / Hydrogen bonding / Hydrogen bonds / Infrared analysis / Infrared spectroscopy / linear models / Low molecular weights / Magnesium Silicates / Molecular Weight / Organic acids / Oxalic acid / Photoelectron spectroscopy / Photoelectrons / Purity / quinclorac / Quinolines / Research Article / Sepiolite / Spectrum analysis / Waste Water Technology / Water Management / Water Pollution Control / X ray photoelectron spectroscopy / X-ray diffraction