High positively charged Fe3O4 nanocomposites for efficient and recyclable demulsification of hexadecane-water micro-emulsion

Rui Wang; Yuxuan Cai; Zhi Su; Xiaoli Ma; Wei Wu

doi:10.1016/j.chemosphere.2021.133050

High positively charged Fe₃O₄ nanocomposites for efficient and recyclable demulsification of hexadecane-water micro-emulsion

Chemosphere. 2022 Mar;291(Pt 3):133050. doi: 10.1016/j.chemosphere.2021.133050. Epub 2021 Nov 26.

Authors

Rui Wang¹, Yuxuan Cai¹, Zhi Su², Xiaoli Ma¹, Wei Wu³

Affiliations

¹ College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830054, China; Xinjiang Key Laboratory of Energy Storage and Photoelectrocatalytic Materials, Xinjiang Normal University, Urumqi, 830054, China.
² College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830054, China; Xinjiang Key Laboratory of Energy Storage and Photoelectrocatalytic Materials, Xinjiang Normal University, Urumqi, 830054, China; Xinjiang Institute of Technology, Akesu, 843100, China.
³ College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830054, China; Xinjiang Key Laboratory of Energy Storage and Photoelectrocatalytic Materials, Xinjiang Normal University, Urumqi, 830054, China. Electronic address: wuwei0523@sina.cn.

PMID: 34843832
DOI: 10.1016/j.chemosphere.2021.133050

Abstract

Oily wastewater not only causes major environmental issues, but also threatens human health. Magnetic nanoparticles (MNPs) are an attractively alternative commercial demulsifiers for their recyclability and high surface area. The wettability and surface charge of magnetic materials are significant factors in oily wastewater treatment. However, the specific influence of surface charge on the demulsification performance has not been rigorously investigated. Herein, a series of MNPs coated by dimethyl-diallyl-ammonium chloride (PDDA) and fulvic acid (FA) (Fe₃O₄/FA/PDDA) with different surface positive charges were synthesized by adjusting the PDDA concentrations and applied in demulsification of hexadecane-water micro-emulsion. The oil-water separation efficiency (Es) was enhanced gradually with increasing the surface positive charge of demulsifiers. Derjaguin-Landau-Verwey-Overbeek (DLVO) theory confirmed that with increasing surface positive potential, the electrostatic attraction between demulsifiers and oil droplets increased, and thus, Es increased. In addition, the superior Es of Fe₃O₄/FA MNPs for hexadecyl trimethyl ammonium bromide (CTAB)-stabilized micro-emulsions and Fe₃O₄/FA/PDDA MNPs for sodium dodecyl sulfate (SDS)-stabilized micro-emulsions further confirmed that electrostatic force was critical in demulsification. The high positively charged Fe₃O₄/FA/PDDA MNPs can be used as an efficient and recyclable demulsifier for hexadecane-water micro-emulsion. This study provides a theoretical basis for designing demulsifiers.

Keywords: DLVO theory; Demulsification; Electrostatic interaction; Fe(3)O(4)/FA/PDDA MNPs; Hexadecane-water micro-emulsion.

MeSH terms

Alkanes
Emulsions
Humans
Nanocomposites*
Water*

Substances

Alkanes
Emulsions
Water
n-hexadecane