title: Proton play in the formation of low molecular weight chitosan (LWCS) by hydrolyzing chitosan with a carbon based solid acid.
abstract: Low molecular weight chitosan (LWCS) constitute a special class of value added chemicals that are primarily obtained from crustacean shells, which are the main water pollutants from crabs and shrimp processing centers. Unlike chitin and chitosan, LWCS possess improved solubility in water and aqueous solutions, making them widely applicable in numerous fields ranging from drug delivery to waste water treatment. Among the methods employed for their production, chemical breakdown by strong liquid acids has yielded good success. However, this method is met with severe concerns arising from the harsh nature of liquid acids, which may corrode the reactors for commercial synthesis, and their limited reusability. The physical methods like ultrasound and microwave are energy intensive in nature, while the enzymatic methods are expensive and offers limited scope for reuse. We have attempted to overcome these problems by employing carbon based solid acid (CSA) for hydrolyzing chitosan to LWCS. CSA can be easily produced using activated carbon, a cost-effective and easily available raw material. Reactions were carried out between chitosan and CSA in a hydrothermal glass reactor and the products, separated by cold centrifugation, were purified and dried. The dried products were characterized for their molecular weight and solubility. Results indicated more than ten-fold decrease in the molecular weight of chitosan and the product exhibited water solubility. The CSA could be used upto four times, without regeneration, to give a consistent quality product. The aqueous solution of resulting LWCS exhibited a pH of 6.03±0.11, as against the acidic pH range of solutions of commercially available LWCS, indicating its suitability for biomedical applications. Our investigation facilitates a 'green approach' that may be employed for commercial production of value added chemicals from waste products of marine industry.
authors.affiliation: Department of Chemical Engineering, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India; Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India.
authors.forename: R Akhil
authors.initials: RA
authors.lastname: Krishnan
authors.affiliation: Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India.
authors.forename: Pranjal
authors.initials: P
authors.lastname: Deshmukh
authors.affiliation: Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Agarwal
authors.affiliation: Polymer and Advanced Materials Laboratory, National Chemical Laboratory, Pashan, Pune 411008, India.
authors.forename: Poorvi
authors.initials: P
authors.lastname: Purohit
authors.affiliation: Polymer and Advanced Materials Laboratory, National Chemical Laboratory, Pashan, Pune 411008, India.
authors.forename: Deepa
authors.initials: D
authors.lastname: Dhoble
authors.affiliation: Mettler-Toledo India Private Limited, Amar Hill, Saki Vihar Road, Powai, Mumbai 400072, India.
authors.forename: Prashant
authors.initials: P
authors.lastname: Waske
authors.affiliation: Mettler-Toledo India Private Limited, Amar Hill, Saki Vihar Road, Powai, Mumbai 400072, India.
authors.forename: Dileep
authors.initials: D
authors.lastname: Khandekar
authors.affiliation: Department of Chemical Engineering, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India. Electronic address: rd.jain@ictmumbai.edu.in.
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Jain
authors.affiliation: Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India. Electronic address: pd.jain@ictmumbai.edu.in.
authors.forename: Prajakta
authors.initials: P
authors.lastname: Dandekar
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D048271:Chitosan / Q000737:chemistry*; D055772:Green Chemistry Technology; D006868:Hydrolysis; D008970:Molecular Weight; D011522:Protons; D059027:Recycling / Q000379:methods; D012995:Solubility; D013464:Sulfuric Acids / Q000737:chemistry*; D014866:Waste Products
chemical_list: D011522:Protons; D013464:Sulfuric Acids; D014866:Waste Products; D002244:Carbon; D048271:Chitosan; C033158:sulfuric acid; D019342:Acetic Acid
keywords: Carbon based solid acid; Chitosan; Green synthesis; Hydrolysis; Low molecular weight chitosan