International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 06 | June 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 5072 Sorption of Zinc (II) Ions onto Modified Jute Fibers (MJF): Application of Two-Parameter Equilibrium Isotherms Shafiul Hossain 1 , Myisha Ahmed Chowdhury 1 1 Lecturer, Department of Chemical Engineering and Polymer Science, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - In the present study, adsorption of Zinc ion on modified Jute fiber (MJF) was done and the equilibrium isotherms were studied. The raw jute fibers were treated by sodium hydroxide and sodium chlorite in order to remove lignin, coloring substances and other alkali soluble compounds from the surface of the fiber. It was then modified by sulfuric acid to increase the proportion of hydroxyl group in the MJF. The MJF samples were characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. The MJF samples were later applied as a potential adsorbent for the removal of Zn (II) ion from aqueous solution. The equilibrium sorption data ware fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. The Langmuir isotherm was best fitted with the experimental data and the maximum monolayer sorption of 142.85 mg/g for Zn (II) ion onto MJF adsorbent was found. The favorability of the adsorption process was indicated by separation factor (RL) and sorption intensity (n) constants of Langmuir and Freundlich isotherms respectively. The Temkin isotherm indicates that the heat of sorption was positive and the process was exothermic. The mean free energy determined by using Dubinin-Radushkevich was 69 KJ/mol which clearly shows that the system followed chemisorption process. Key Words: Modified Jute Fibers (MJF), Heavy metals, Zn (II) ion, Adsorption, Isotherm 1. INTRODUCTION Heavy metals are toxic and carcinogenic in nature, which poses serious threats on the natural environment and living organisms. They are released in natural aqueous system due to different human activity such as industrial activity, smelting operations, agriculture and mining work. The major pollutants released from different industries are lead (Pb), zinc (Zn), copper (Cu), arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni) and mercury (Hg) [1]. There are different techniques for removal of heavy metal ions from solutions including chemical precipitation [2, 3], solvent extraction [4]; coagulation and flocculation [5], and membrane processes [6], osmosis [7] and adsorption [8, 9, 10]. Among these methods, adsorption is one of the most efficient physico-chemical treatment for heavy metal removal as it has overcome inherent limitations of other techniques such as high cost, large amount of sludge formation, low efficiency, and sensitive operating conditions [11, 12]. There are several commercial adsorbent such as graphene oxide [13] and activated carbon [14, 15, 16] widely used for the removal of heavy metals. Despite their high efficiency, they are not affordable for many small-scale industrial concerns in many less developed countries [17]. To overcome this issue, Researchers are trying different low cost, naturally available adsorbents and found that agriculture waste material such as sugarcane bagasse [18, 19], raw rice bran[17], sawdust [20], ricehusk [21], neem bark [22], coconut husk [23] and pine bark [24] to be a viable alternative. To establish an adsorbate-adsorbent system, the role of a well suited equilibrium isotherm is unavoidable as it gives information about the maximum adsorption capacity, adsorption system design etc. [25, 26, 27]. Jute fiber is one of the most produced natural fibers in India (mainly West Bengal), Bangladesh, China, and Myanmar. The abundance of jute fibers accounts for the feasibility of choosing it as raw material in this paper. The principal constituents of jute fiber are mainly cellulose (58-63 %), hemicellulose (20-24 %), lignin (12-15 %), and some other small quantities of constituents like fats, pectin, aqueous extract etc. [28]. The hydroxyl and carboxyl functional group present in cellulose helps to bind the metal ion by forming complex [29, 30]. The raw cellulose fibers are reported to have low efficiency compared to the treated one [31, 32, 33]. In this work jute fiber had been modified using chemical treatment method. Biomass characterization was determined with Fourier transform infrared (FT-IR) spectrum and scanning electron microscope (SEM). The modified jute fibers were then used to remove Zn (II) from the aqueous solution and different two-parameter equilibrium isotherms (Langmuir, Freundlich, Temkin and Dubinin- Radushkevich) were studied to define the Jute fiber-Zn (II) system. 2. MATERIAL AND METHOD 2.1. Materials The modified jute fiber (MJF) was prepared from raw Jute (Corchorus capsularis) which is the most available fiber of Bangladesh. The jute fiber was purchased from the local market of Bangladesh. Sulphuric acid (H2SO4) and Acetic acid