Pickering emulsion-embedded hierarchical solid-liquid hydrogel spheres for static and flow photocatalysis

Yalin Lan; Meng Yu; Dongqing He; Yanming Wang; Qing Bo Meng; Hongwei Huang; Yu Zhang; Tianyi Ma; Xi-Ming Song

doi:10.1016/j.jcis.2021.01.020

Pickering emulsion-embedded hierarchical solid-liquid hydrogel spheres for static and flow photocatalysis

J Colloid Interface Sci. 2021 May:589:587-596. doi: 10.1016/j.jcis.2021.01.020. Epub 2021 Jan 14.

Authors

Yalin Lan¹, Meng Yu¹, Dongqing He¹, Yanming Wang¹, Qing Bo Meng¹, Hongwei Huang², Yu Zhang³, Tianyi Ma⁴, Xi-Ming Song⁵

Affiliations

¹ Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China.
² School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.
³ Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China. Electronic address: zhangy@lnu.edu.cn.
⁴ Centre for Translational Atomaterials, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia. Electronic address: tianyima@swin.edu.au.
⁵ Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China. Electronic address: songlab@lnu.edu.cn.

PMID: 33503508
DOI: 10.1016/j.jcis.2021.01.020

Abstract

Pickering emulsion-based photocatalysis is considered to be a promising system due to its large active surface area and water/oil spatial separation capability for enrichment of substrates and products. In this work, a novel hierarchical structure composed of calcium alginate gel sphere wrapped ionic liquid-in-water Pickering emulsion with TiO₂ in the water phase, which are stabilized by graphene oxide, is prepared via a facile one-step emulsion gelation method. Such subtle combination of Pickering emulsion, hydrogel and TiO₂ with a multi-stage solid-liquid assemblage structure shows enhanced degradation activity of 2-naphthol into small molecular alkanes under simulated solar irradiation. The photodegradation activity is attributed to the ionic liquid as adsorption medium for 2-naphthol, and the high-efficient charge separation at graphene oxide/TiO₂ interface superior to that of pure TiO₂. More importantly, the as-prepared millimeter-sized assembled gel spheres can be directly used as the column filler to construct continuous flow photocatalytic system, maintaining the promising performance in removing pollutants from water with ~100% remove ability of 2-naphthol on stream. A charge transfer mechanism of the photocatalyst is proposed, i.e. photogenerated charges are separated in TiO₂/graphene oxide p-n heterostructure at the interface of Pickering emulsion droplets.

Keywords: Flow photocatalysis; Hydrogel sphere; Ionic liquid; Pickering emulsion; Titanium dioxide.