Highly recyclable and super-tough hydrogel mediated by dual-functional TiO2 nanoparticles toward efficient photodegradation of organic water pollutants

Yiying Yue; Xianhui Wang; Qinglin Wu; Jingquan Han; Jianchun Jiang

doi:10.1016/j.jcis.2019.12.069

Highly recyclable and super-tough hydrogel mediated by dual-functional TiO₂ nanoparticles toward efficient photodegradation of organic water pollutants

J Colloid Interface Sci. 2020 Mar 22:564:99-112. doi: 10.1016/j.jcis.2019.12.069. Epub 2019 Dec 28.

Authors

Yiying Yue¹, Xianhui Wang¹, Qinglin Wu², Jingquan Han³, Jianchun Jiang⁴

Affiliations

¹ College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, Jiangsu, China.
² School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge 70803, LA, USA.
³ College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China. Electronic address: hjq@njfu.edu.cn.
⁴ College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China; Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, Nanjing 210042, Jiangsu, China. Electronic address: bio-energy@163.com.

PMID: 31911232
DOI: 10.1016/j.jcis.2019.12.069

Abstract

A novel photocatalytic hydrogel was prepared by loading TiO₂ nanoparticles (TiO₂ NPs) onto the surface of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized chitin nanofibers (TOCNs), which were further incorporated into the polyacrylamide (PAM) matrix. The resultant hydrogel exhibited a macro-porous structure with a low density (~1.45 g/cm³) and high water content (~80%). The well-dispersed TiO₂ NPs not only acted as a crosslinking agent for bridging the three-dimensional porous network structure, but also endowed the hydrogel with good catalytic activity. After the introduction of TiO₂ accounting for 10 wt% of the hydrogel mass, the hydrogels showed compressive strength of 1.46 MPa at 70% strain, tensile stress of 316 kPa, tensile strain of 310%, toughness of 47.25 kJ/m³ and fatigue resistance. Compared with neat TOCN-PAM hydrogel, the uniaxial compressive and tensile strengths of the TiO₂-TOCN-PAM10 hydrogel increased 6.35-fold and 3.70-fold, respectively. Furthermore, the removal of methyl orange (MO) was attributed to the synergistic effect of the adsorption and photocatalytic degradation of the hydrogels. The hydrogels adsorbed up to 8.5% of MO after 150 min of adsorption and a photocatalytic degradation rate of 97.3% achieved after 90 min of UV irradiation at pH = 2. Especially, the TiO₂-TOCN-PAM10 hydrogel exhibited excellent recycling performance: its MO removal efficiency was around 96% even after 10 reuse cycles. The as-prepared hydrogels, with characteristics of excellent stretchability, photocatalytic activity and recyclability, are expected to be used in alleviating organic pollutants in practical wastewater treatments.

Keywords: Hydrogel; Mechanical strength; Photocatalytic performance; Reutilization; TEMPO-oxidized chitin nanofiber.