ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY https://doi.org/10.14233/ajchem.2018.21139 INTRODUCTION At present time, it is been observed that the rapid growth of industrialization has turned out to be a curse for the environ- ment owing to the uncontrolled discharging of the industrial effluents and wastewater in aqueous bodies contaminated with heavy metal ions such as Cu(II), Cd(II), Zn(II), Fe(II), etc. The different studies conducted indicate that the cadmium is the one of the most hazardous and toxic metal which is discharged in water through various industries such as melting, plating, metal mining, batteries, oil paint, pigments, pesticides and alloys [1,2]. Cadmium affects the physio-chemical beha- viour and since it has propensity to act as biological catalyst [3]. Due to the hazardous and toxic property of the heavy metals, different techniques have been put to use for the extirpating of heavy metal, methods viz. chemical precipitation [4], reduc- tion-oxidation [5], ion-exchange [6] and biological process [7]. Various studies illustrate that among the different methods of extirpating of heavy metals, adsorption technique is more promising owing to its economical and easy operation. Several studies have been devoted on this method [8,9]. For efficient extirpating of heavy metal ions, it is necessary that adsorbent should have properties like surface area should be high and must possess high adsorption capacity, appropriate pore size and volume, mechanical stability, compatibility, ease of Study of Modified Banana Fiber as Adsorbent for Cadmium(II) Ions from Aqueous Solution MANISH MASIH * and PRASHANT ANTHONY Department of Chemistry, Sam Higginbottom University of Agriculture, Technology & Sciences, Allahabad-211 007, India *Corresponding author: Fax: +91 532 2684012; E-mail: manishmasih14@gmail.com Received: 20 November 2017; Accepted: 31 January 2018; Published online: 29 March 2018; AJC-18835 Raw banana fiber (RBF), acid treated banana fiber (ATBF) from banana stem was evaluated as adsorbent for the elimination Cd 2+ from solution. The Cd 2+ solution of 1000 mg/L concentration was prepared from Cd(NO3)2 and different concentrations were prepared by dilution of stock solution. Effects of adsorbent dose, contact time, temperature, initial metal concentration and pH study were evaluated. Langmuir and Freundlich isotherms were employed to describe adsorption capacity The maximum amounts of cadmium(II) adsorbed (qm), which was evaluated by Langmuir isotherm, were 0.469 mg/g and 5.230 mg/g, and highest R 2 (0.9968, 0.9815,) for raw banana fiber and acid treated banana fiber, respectively. Pseudo-second order kinetics best fitted with R 2 = (0.9457), (0.9571) for raw banana fiber and acid treated banana fiber, respectively. Thermodynamic parameters obtained were ∆G° (-8.268) kJ mol -1 K -1 , ∆H° (-9.874), kJ mol -1 K -1 and ∆S° (-5.152) kJ mol -1 for acid treated banana fiber and spontaneity decreases with increase in temperature in case of raw banana fiber and acid treated banana fiber. This indicates that the system is exothermic. Banana stems possess feasible characteristics for making an adsorbent and acid treated banana fiber is more efficient for removal of Cd 2+ ion from its aqueous solution. Keywords: Adsorption isotherms, Banana stem, Kinetics, Thermodynamics, Cadmium. Asian Journal of Chemistry; Vol. 30, No. 5 (2018), 1031-1036 regeneration, easy accessibility, cost effectiveness and environ- ment friendliness [10]. Different agricultural wastes and non- conventional material have been focused and utilized by resear- chers as to remove heavy metal ions from water bodies are canola residue [11], melon seed husk [12]; cassava waste [13], groundnut husk [14], maize cob [15], orange waste [16], Manihotsculentacranz waste [17,18], rape straw [19], feather, palm fruit fibre [20,21] and rice husk [22]. Among all these adsorbents banana plant has also demonstrated the tendency to remove heavy metals from aqueous solution. Primarily banana is cultivated for fruit, fibre production and sometimes as an ornamental plant. It is normally tall and sturdy, in some species 8 m of height can be reached. In this study the removal of cadmium ion from aqueous solution by utilizing banana fiber as well as sulfuric acid treated banana fiber was evaluated as an adsorbent. Adsorption inten- sity of the adsorbate on adsorbent surface and adsorption potentials of adsorbent were evaluated by adsorption kinetics, thermodynamics studies and Langmuir, Freundlich isotherms, respectively. EXPERIMENTAL Adsorbent preparation: Banana stem was obtained locally from Allahabad. It was chopped into small chunks of