Linear and crosslinked Polyurethanes based catalysts for reduction of methylene blue

Misbah Sultan; Asma Javeed; Maliha Uroos; Muhammad Imran; Farhat Jubeen; Shazia Nouren; Nazish Saleem; Ismat Bibi; Rashid Masood; Waqas Ahmed

doi:10.1016/j.jhazmat.2017.10.019

Linear and crosslinked Polyurethanes based catalysts for reduction of methylene blue

J Hazard Mater. 2018 Feb 15:344:210-219. doi: 10.1016/j.jhazmat.2017.10.019. Epub 2017 Oct 10.

Authors

Affiliations

¹ Institute of Chemistry, University of the Punjab, Lahore, Pakistan. Electronic address: misbah_sultan@yahoo.com.
² Institute of Chemistry, University of the Punjab, Lahore, Pakistan.
³ Department of Biological Sciences, Forman Christian College University, Lahore, Pakistan.
⁴ Department of Chemistry, GC Women University, Faisalabad, Pakistan.
⁵ Department of Chemistry, Govt. College Women University, Sialkot, Pakistan.
⁶ Department of Chemistry, Islamia University Bahawalpur, Pakistan.
⁷ Department of Textile Processing, National Textile University, Faisalabad, Pakistan.

PMID: 29035715
DOI: 10.1016/j.jhazmat.2017.10.019

Abstract

The large amount of synthetic dyes in effluents is a serious concern to be addressed. The chemical reduction is one of the potential way to resolve this problem. In this study, linear and crosslinked polyurethanes i.e. LPUR & CLPUR were synthesized from toluene diisocyanate (TDI), polyethylene glycol (PEG;1000g/mole) and tetraethylenepentamine (TEPA). The structure and morphology of synthesized materials were examined by FTIR, SEM and BET. The CLPUR was found stable in aqueous system with 0.80g/cm³ density and 16.4998m²g^-1 surface area. These materials were applied for the reduction of methylene blue in presence of NaBH₄. Both, polymers catalyzed the process and showed 100% reduction in 16 and 28mins., respectively, while, the reduction rate was significantly low in absence of these materials, even after 120mins. Furthermore, negligible adsorption was observed with only 7% removal of dye. The best reduction rates were observed at low concentration of dye, increasing concentration of NaBH₄ and with more dosage of polymeric catalyst. The kinetic study of process followed zero order kinetics. It was hence concluded that both synthesized polymers played a catalytic role in reduction process. However, stability in aqueous system and better efficiency in reduction process endorsed CLPUR as an optimal choice for further studies.

Keywords: Catalyst; Cellular materials; Crosslinking; Methylene blue; Polyurethane.