Synthesis of an Efficient Adsorbent Hydrogel Based on Biodegradable Polymers for Removing Crystal Violet Dye from Aqueous Solution
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Synthesis of an efficient adsorbent hydrogel based on biodegradable polymers for removing crystal violet dye from aqueous solution Riham R. Mohamed, Mahmoud H. Abu Elella, Magdy W. Sabaa & Gamal R. Saad Cellulose ISSN 0969-0239 Cellulose DOI 10.1007/s10570-018-2014-x 1 23 Your article is protected by copyright and all rights are held exclusively by Springer Nature B.V.. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Cellulose https://doi.org/10.1007/s10570-018-2014-x (0123456789().,-volV)(0123456789().,-volV) ORIGINAL PAPER Synthesis of an efficient adsorbent hydrogel based on biodegradable polymers for removing crystal violet dye from aqueous solution Riham R. Mohamed . Mahmoud H. Abu Elella . Magdy W. Sabaa . Gamal R. Saad Received: 16 May 2018 / Accepted: 22 August 2018 Ó Springer Nature B.V. 2018 Abstract Water pollution with toxic dyes threatens Keywords Xanthan gum Á Poly (N-vinyl human health world-wide. Herein, we prepared an imidazole) Á Hydrogel Á Crystal violet Á Adsorption Á effective adsorbent hydrogel for removing toxic Regeneration cationic crystal violet (CV) dye from its aqueous solutions using biodegradable polymers such as; xanthan gum (XG) and poly (N-vinyl imidazole) (PVI). The structure and morphology of the prepared Introduction XG/PVI hydrogel and CV loaded hydrogel were characterized by FTIR, FE-SEM and XRD, while Water pollution is considered one of the most serious thermal stability of investigated hydrogel was charac- problems worldwide as it threatens human health due terized by TGA. Adsorption experiments were carried to rapid industrialization (Kumari et al. 2017). Water out as functions of initial concentration of CV dye, the is polluted with toxic dyes, toxic heavy metal ions and adsorbent dose, pH of solution, temperature, and organic contaminants (Ghorai et al. 2014). Recently contact time. Results were analyzed using Langmuir the use of synthetic dyes in different industries and Freundlich isotherm models. It is found that the increased such as; leather, ink, textile, food process- data were well fitted by Langmuir model. The ing, cosmetics, rubber and paper products because maximum adsorption capacity achieved was found to they are cheap and easily available (Mittal et al. 2014). be 453 mg g-1 due to electrostatic, H-bonding and Dyes are difficult to eliminate due to their synthetic dipole–dipole interactions between adsorbent surface origin and complex structure which makes them very and CV molecules. The adsorption kinetic studies stable (Kumari and Abraham 2007; Martins et al. showed that the adsorption followed pseudo-first order 2017; Mittal et al. 2016). and intraparticle diffusion kinetic models. Regenera- Moreover, dyes are extremely dangerous pollutants tion (desorption) studies showed that XG/PVI hydro- due to their toxicity and carcinogenic nature, poor gel is an interesting adsorbent for removing toxic dyes degradability and high solubility in water, so, they from waste water. accumulate in living cells and cause hazardous effects on human health (Mittal et al. 2014, 2016). Among various dyes, crystal violet (CV) dye (Fig. 1a)—which R. R. Mohamed (&) Á M. H. Abu Elella Á is the target of our research—is a kind of cationic M. W. Sabaa Á G. R. Saad triphenyl methane dye that is responsible for cancer Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt and several eye irritation to human beings (Dil et al. e-mail: [email protected] 2016; Ghorai et al. 2014; Hameed 2008; Xu et al. 123 Author's personal copy Cellulose Fig. 1 Chemical structures of a crystal violet dye CV, b XG and c PVI 2011). Various removal methods have been studied for (Benny et al. 2014; Bilanovic et al. 2016; Mittal et al. water purification from industrial drains by floccula- 2016; Talukdar and Kinget 1995). It was discovered tion, photocatalytic, membrane separation, ozonation, by Allene Jeanes and her co-workers in 1961 (Jeanes coagulation, ion exchange and electrolysis. However, et al. 1961). XG is a water soluble anionic polysac- these processes vary in their effectiveness, costs, and charide, it is known as microbial polysaccharide environmental impacts (Allegre et al. 2004; Hao et al. because it is extracted from Xanthomonas campestris. 2000; Mittal et al. 2016; Sanghi et al. 2007). Adsorp- XG structure (Fig. 1b) is composed of b-(1-4)-D- tion is one of the most effective techniques used for glucopyranose glucan in backbone chain that is linked pollutants removal from contaminated water as it is to side chain (a-D-mannopyranose-(2-1)-b-D-glu- simple, efficient, low cost, eco-friendly technique, curonic acid-(4-1)-b-D-mannopyranose) through b- (Al-Qodah 2000; Laaz et al. 2016; Mittal et al. 2014). (3-1) linkages. The molecular formula of its repeating In the past decades, scientists became interested in unit is C35H49O29 (Benny et al. 2014; Garcıa-Ochoa natural polysaccharides as adsorbents for purifying et al. 2000; Pandey and Ramontja 2016). XG is rarely water from toxic dyes because polysaccharides are used alone as adsorbent due to its solubility in water, available, non-toxic, eco-friendly, biodegradable, so it should be modified to be used as adsorbent (Jalali inexpensive, and easily modified (Ghorai et al. 2014; et al. 2016). Mittal et al. 2016; Parker et al. 2012). Polysaccharides On the other hand, poly (N-vinyl imidazole) (PVI), adsorb dyes through the electrostatic interactions Fig. 1c, is a water soluble synthetic polymer, it is between adsorbent and dyes (Mittal et al. 2015, 2016). produced via free radical polymerization of N-vinyl Xanthan gum (XG) is one of the natural polysac- imidazole (Caner et al. 2007). PVI contains imidazole charides that are used in different applications such as; moiety that contains nitrogen atom, so it forms wastewater treatment, cosmetics, pharmaceuticals and complexes with different toxic heavy metal ions from food industry because it has good properties including their aqueous solutions through coordination bonds biodegradability, biocompatibility and non-toxicity (Broekema et al. 1982; El-Hamshary et al. 2014; Pekel 123 Author's personal copy Cellulose and Gu¨ven 2004). PVI has good properties such as; dissolved in 30 mL of benzene in two-neck round thermal stability, biocompatibility and biodegradabil- bottomed flask and stirred at 70 °C under N2 atmo- ity (Hu et al. 2017). sphere. Then 10 mL (0.1 M) of N-vinyl imidazole was Hydrogels are three-dimensional (3D) networks dropwisely added to the above solution. After that, the formed from physically or chemically crosslinked solution was stirred for 3 h at 70 ± 2 °C. After the polymers, so, they are insoluble in many different time was elapsed, the product was precipitated in solvents. They are capable of absorbing large amount acetone. PVI product was filtered and washed several of water or biological fluids due to the presence of times with acetone to remove unreacted monomer. hydrophilic groups such as; hydroxyl (–OH), car- The final product was dried in vacuum oven at 40 °C boxylic acid (–COOH), sulphuric acid (–SO3H) for 24 h and recovered with 80% yield. The viscosity groups and imidazole rings along chains of the average molecular weight of PVI was determined as hydrogels (Karadag˘ et al. 1995; Pekel and Gu¨ven 7.4 9 105 g mol-1. 2002). They function in water purification by remov- ing heavy metal ions, and then can be regenerated Synthesis of XG/PVI hydrogel easily (Pekel and Gu¨ven 2004; Pekel et al. 2000). Therefore, we expect that synthesized hydrogels 0.5 g of XG was dissolved in 50 mL of distilled water based on biodegradable polymers as XG and PVI under continuous stirring for 1 h then 0.5 g of PVI including different groups such as carboxylate, dissolved in 50 mL of distilled water then it was hydroxyl and imidazole groups along chains which dropwisely added. The mixture was kept under act as efficient adsorbents for removing toxic cationic constant stirring for 2 h at room temperature crystal violet dye from aqueous solutions. The dye (* 30 °C). The precipitated hydrogel was separated adsorption capacity of the prepared XG/PVI hydrogel via filtration using a G2 sintered glass funnel, was studied as a function of the initial concentration of collected by filtration, washed several times with dye, pH, temperature and contact time. The molecular distilled water and then dried in vacuum oven at 40 °C structure and morphology of XG/PVI hydrogel and for 24 h. XG/PVI loaded with CV are characterized via FTIR, XRD and FE-SEM. Swelling measurement The ability of XG/PVI hydrogel for water uptake was Materials and experimental methods studied in phosphate buffered saline (PBS) (pH 7.4) at room temperature (* 30 °C). 50 mg of hydrogel was Materials immersed in 25 mL of PBS at different time periods until equilibrium water uptake was reached. The Xanthan gum was purchased from Alpha-Chemika, swollen hydrogel was removed from PBS then excess India. N-vinyl imidazole was purchased from Alfa water on the surface was removed with filter paper and AesarÒ-Germany. Crystal violet dye was obtained finally weighed. The percentage of the swelling was from Loba chemi Pvt. Ltd., Mumbai, India.