Titanium dioxide decorated natural cellulosic Juncus effusus fiber for highly efficient photodegradation towards dyes

doi:10.1016/j.carbpol.2020.115830

Carbohydrate Polymers

Volume 232, 15 March 2020, 115830

https://doi.org/10.1016/j.carbpol.2020.115830 Get rights and content

Highlights

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A natural cellulosic Juncus effusus fiber was used for photodegradation towards dyes.
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Three-dimensional network structure and interconnected channels were observed.
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99.9 % of degradation efficiency was obtained towards different types of dyes.
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An orientate fabric was fabricated using the prepared TiO₂-JE fibers.

Abstract

The removal of dyes via photocatalytic degradation has been identified as an eco-friendly method for producing clean and purified water. Natural cellulosic fibers are significant renewable resource and important in a wide range of applications. Herein, we report a natural cellulosic Juncus effusus (JE) fiber with 3D network structure as a framework to provide controllable space for the growth of TiO₂ particles. The TiO₂-JE showed remarkable activity in the removal of C.I. Reactive Red 120 (RR120), C.I. Direct Yellow 12 (DY12), and methylene blue (MB) with a photodegradation efficiency of 99.9 % under simulated sunlight irradiation. Additionally, an orientate fabric was fabricated using the prepared TiO₂-JE fibers for the photocatalytic degradation of dye-contaminated water in the sun, further confirming its practical application. The TiO₂ decorated natural cellulosic JE fiber can be a promising material for photocatalysis and sustainable chemistry.

Graphical abstract

Introduction

Water is one of the most vital requirements of living organisms on earth (Vorosmarty et al., 2010). A common observation is that water is abundant on earth but only a small amount is easily accessible, and in the fresh water cases, this is especially true for human (Oki, 2006). However, industrial processes produce toxic wastewater containing aromatic compounds from dyes, which have harmful effects on human immune system and ecosystems. (Dhanya & Aparna, 2016; Meseck, Kontic, Patzke, & Seeger, 2012; Zhang, Li, Li, Li, & Yang, 2018). Conventional adsorption technologies, such as biological degradation (Oh et al., 2014), chemical oxidation (Li, Zhang, Liang, & Yediler, 2013; Sohrabi, Ross, Martin, & Barker, 2013), activated carbon absorption and carbon nanotube nanocomposite absorption (Gao, Zhao, Cheng, Wang, & Zheng, 2013; Hashemian, Salari, Salehifar, & Atashi Yazdi, 2013), ultrafiltration by chemical agents or physical filtration, reverse osmosis, coagulation, and ion exchange (Karimifard & Alavi Moghaddam, 2018; Konstantinou & Albanis, 2004; Natarajan, Thomas, Natarajan, Bajaj, & Tayade, 2011; Tang & An, 1995), because of quantity production and harsh experimental conditions, generation of by-products, and regeneration and reasonable disposal of adsorbents restrict their broader, acceptable application.

As one of the most widely used photodegradable materials, TiO₂ has attracted much attention for the treatment of organic and contaminated components (Hoşgün & Aydın, 2019), due to its biological activity and chemical stability, high oxidizing power toward organic materials, low price, and non-toxicity (Fernández-Ibáñez et al., 2015; Wang et al., 2017; Yang et al., 2017). However, as a single constituent, TiO₂ has some disadvantages, most of which are associated with its limited photocatalytic efficiency in the visible light range on account of its wide band gap and rapid recombination of hole–electron pairs (Da Vià, Recchi, Gonzalez-Yañez, Davies, & Lopez-Sanchez, 2017), low absorption capacity, and low surface area (Cheng, Wang, Zhao, & Han, 2014), thereby reducing its photocatalytic activity. Moreover, in the practical applications, residual TiO₂ nanoparticles in the photocatalytic reaction solution need to be recycled. To address these problems, a large number of synthetic materials, such as polymer films and porous inorganic membranes (Leong et al., 2014; Liu, Chen, Lv, Feng, & Meng, 2015), porous composites (Lefatshe, Muiva, & Kebaabetswe, 2017), composite sponges (Hickman, Walker, & Chowdhury, 2018), clays and clay minerals, zeolites, silica gels, and metal-organic frameworks, as well as complicated methods synthesis have been used to immobilize nano-TiO₂ particles (Butburee et al., 2018; Gu et al., 2016; Kangwansupamonkon, Klaikaew, & Kiatkamjornwong, 2018; Meseck et al., 2012). However, most methods have their limitations owing to complicated process of synthesis, inconvenient, harsh, and not environment friendly conditions, as well as expensive raw materials. Therefore, for the applications of industrial dye wastewater adsorption, the cost of the dye wastewater adsorbent has to be further reduced.

Juncus effusus (JE) fiber is natural cellulosic fiber with excellent biocompatibility, non-hazard, low cost, substantial biodegradability, and recyclability, which has extensively planted in provinces in China such as Jiangxi, Sichuan, and Guizhou (Wang, Ke, Tang, Yuan, & Ye, 2009). More importantly, compared with other cellulose materials used for dispersing nanoparticles to the photocatalytic degradation experiment, such as nano ZnO-blended cellulose acetate-polyurethane membrane(Rajeswari, Vismaiya, & Pius, 2017), β-FeOOH@tunicate cellulose hydrogels (Wang et al., 2020), TiO₂-MFC (Microfibrillated cellulose) thin films (Ng & Leo, 2019), Ag₃PO₄/nanocellulose composite (Lebogang, Bosigo, Lefatshe, & Muiva, 2019), and N-doping of cellulose photocatalytic materials (Chhetri et al., 2017), JE fiber exhibits the natural three-dimensional network structure and interconnected channels, which can be a promising candidate for the in-situ growth of TiO₂ particles by providing a limited space and controlling the size. It is considered that the 3D network structure of an adsorbent is beneficial for adsorption of dyes and the control growth of TiO₂ is vital to photodegradation performance towards dye in water (Froschl et al., 2012). Therefore, the TiO₂-JE material can be a promising material for alleviating the environmental pollution via adsorption and photodegradation towards dyes from wastewater.

Herein, we developed a novel route to immobilize the functional photocatalyst of TiO₂ particles utilizing 3D-porous cellulosic JE fibers. The TiO₂-JE fibers were prepared using a sol-gel approach, followed by stewing and baking crystal treatment. The aim of designing TiO₂-JE fiber material was to bring out the excellent properties of respective components and through the combination of inorganic and organic enhance their respective performance, to make up for their respective shortcomings. JE fiber is one of the potential candidates for supporting TiO₂ particles due to its 3D net-working structure and the composite was prepared by incorporating the photocatalyst with a 3D interpenetrated network structure based on TiO₂ particles with JE fibers for the absorption and degradation of dyes from water.

Section snippets

Materials

The chemicals used for synthesis include tetrabutyl orthotitanate (TBOT) (97 %, Aldrich, USA), acetic acid (99.9 %, Aldrich, USA), and absolute ethanol (99.9 %, Merck, USA). JE fibers were obtained from Jiangxi Juncus effusus Co. Ltd., Jiangxi, China. C.I. Reactive Red 120 (RR120), C.I. Direct Yellow 12 (DY12), and methylene blue (MB) were supplied by Luthai Textile Co. Ltd., Shandong, China. Deionized water was used in all the experiments.

Preparation of TiO₂-JE composites

In recent years, the method of sol-gel has been

Characterization of TiO₂-JE composites

Fig. 2 and Fig.S1 show the surface morphologies, cross sections and longitudinal sections of the JE and TiO₂-JE fibers. From the SEM images of the cross-sectional and longitudinal sectional views, a natural 3D porous structure and the rough surface of the JE fiber were clearly observed. Fine porous structure and excellent surface properties improve the composite materials surface activity. Some TiO₂ particles were formed after aggregation, as shown in Fig. 2(b1)–(b3) and Fig. S1(a1)–(c3). As

Conclusions

In summary, the TiO₂ decorated mesoporous JE fibers were successfully prepared via a simple sol-gel processes using precursors. The natural cellulosic JE fiber has concluded to be a promising material for the controllable growth of TiO₂ due to its 3D network structure. The TiO₂-JE fiber showed stable properties and high degree of adsorption and excellent photodegradation for dyes under UV and visible light; nearly 99.9 % each of RR120, DY12 and MB were degraded within 50 min, 60 min and

Acknowledgments

We are very grateful for the financial support from the National Natural Science Foundation of China (51773158, 21905214) and the China Chemical Fibers Association, Lv Yu Foundation (CCFALY2018-2-4).