title: Fibrous polymer-grafted chitosan/clay composite beads as a carrier for immobilization of papain and its usability for mercury elimination.
abstract: Papain, which is an industrially important enzyme, has been immobilized on fibrous polymer-modified composite beads, namely poly(methacrylic acid)-grafted chitosan/clay. Characterization studies have been done using FTIR and SEM analysis. Operating parameters such as pH and initial concentration of papain have been varied to obtain the finest papain immobilized polymer-modified composite beads. The immobilization capacity of composite beads has been determined as 34.47 ± 1.18 (n = 3) mg/g. The proteolytic activity of immobilized papain was operated using bovine serum albumin (BSA) and maximum velocity (V max) and Michaelis-Menten constant (Km) values of the free and immobilized enzymes were determined using Lineweaver-Burk and Eadie-Hofstee equations. Usability of papain immobilized polymer-modified composite beads as adsorbents for the elimination of mercury was investigated. The maximum removal capacity of PIPMC beads has been found to be 4.88 ± 0.21 mg Hg/g when the initial metal concentration and weight of polymer-modified composite beads were 50 mg/L and 0.04 g at pH 7, respectively. Mercury removal performance of the papain immobilized polymer-modified composite beads was investigated in conjunction with Cu (II), Zn (II) and Cd (II) ions. The mercury adsorption capacity of papain immobilized polymer-modified composite beads was a slight reduction from 1.15 to 0.89 mg/g in presence of multiple metal salts.
authors.affiliation: Department of Chemistry, Faculty of Science and Arts, Kırıkkale University, Yahşihan, 71450, Kırıkkale, Turkey. aumetin@gmail.com.
authors.forename: Ayşegül Ülkü
authors.initials: AÜ
authors.lastname: Metin
authors.affiliation: Department of Chemical Engineering, Faculty of Engineering, Hitit University, 19030, Çorum, Turkey.
authors.forename: Erol
authors.initials: E
authors.lastname: Alver
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D048271:Chitosan / Q000737:chemistry*; D000077215:Clay; D004800:Enzymes, Immobilized / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D010206:Papain / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D000538:Aluminum Silicates; D004800:Enzymes, Immobilized; D011108:Polymers; D048271:Chitosan; D010206:Papain; D008628:Mercury; D000077215:Clay
keywords: Composite; Enzymatic activity; Grafting; Mercury removal; Papain