Super water absorbing polymeric gel from chitosan, citric acid and urea: Synthesis and mechanism of water absorption

Abathodharanan Narayanan; Ravishankar Kartik; Elanchezhian Sangeetha; Raghavachari Dhamodharan

doi:10.1016/j.carbpol.2018.03.028

Super water absorbing polymeric gel from chitosan, citric acid and urea: Synthesis and mechanism of water absorption

Carbohydr Polym. 2018 Jul 1:191:152-160. doi: 10.1016/j.carbpol.2018.03.028. Epub 2018 Mar 14.

Authors

Abathodharanan Narayanan¹, Ravishankar Kartik¹, Elanchezhian Sangeetha¹, Raghavachari Dhamodharan²

Affiliations

¹ Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
² Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India. Electronic address: damo@iitm.ac.in.

PMID: 29661303
DOI: 10.1016/j.carbpol.2018.03.028

Abstract

A new superabsorbent with maximum water absorption capacity of ∼1250 g/g is prepared by hydrothermal synthesis from sustainable and biodegradable resources such as chitosan, citric acid and urea (denoted as 'CHCAUR'). CHCAUR is characterized extensively by various analytical techniques such as PXRD, SSNMR, FTIR, and TGA. Pure and saline water absorption study showed that CHCAUR could be a better adsorbent compared to the super absorbent polymer (SAP) used in commercial diaper material. The mechanism of water absorption is shown to arise out of a combination of electrostatic attraction of water to the ionic crosslinks and the presence of macropores as well as undulated surface due to the formation of nanofibrous bundles. When applied to soil CHCAUR was found to decrease water evaporation rate significantly.

Keywords: Chitosan; Hydrothermal synthesis; Macroporous polymer; Superabsorbent; Water retention in soil.