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Linear and crosslinked Polyurethanes based catalysts for reduction of methylene blue
Misbah Sultan1, Asma Javeed1, Maliha Uroos1
1Institute of Chemistry, University of the Punjab, Lahore, Pakistan.
Journal of Hazardous Materials
|October 17, 2017
Summary
Synthesized polyurethanes, linear (LPUR) and crosslinked (CLPUR), effectively catalyze methylene blue reduction in effluents. CLPUR demonstrated superior stability and efficiency, achieving 100% dye reduction rapidly.
Area of Science:
- Environmental Chemistry
- Polymer Science
- Catalysis
Background:
- Industrial effluents often contain synthetic dyes, posing environmental risks.
- Chemical reduction using catalysts offers a viable method for dye degradation.
- Polyurethanes present potential as novel catalytic materials for pollutant removal.
Purpose of the Study:
- To synthesize and characterize linear (LPUR) and crosslinked (CLPUR) polyurethanes.
- To evaluate the catalytic efficiency of LPUR and CLPUR in the reduction of methylene blue dye.
- To investigate the factors influencing the reduction process and determine its kinetics.
Main Methods:
- Polyurethanes synthesized using toluene diisocyanate (TDI), polyethylene glycol (PEG), and tetraethylenepentamine (TEPA).
- Material characterization via Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis.
- Methylene blue reduction experiments conducted with and without polymeric catalysts in the presence of sodium borohydride (NaBH4).
Main Results:
- CLPUR exhibited good aqueous stability with a density of 0.80 g/cm³ and a surface area of 16.4998 m²/g.
- Both LPUR and CLPUR catalyzed the reduction of methylene blue, achieving 100% reduction in 16 and 28 minutes, respectively.
- The reduction rate was significantly slower without the polymers, and adsorption was negligible (7% dye removal). Optimal conditions included low dye concentration, increased NaBH4 concentration, and higher catalyst dosage.
- Kinetic studies indicated zero-order reaction kinetics.
Conclusions:
- Synthesized polyurethanes, LPUR and CLPUR, act as effective catalysts for methylene blue reduction.
- CLPUR is identified as the optimal choice due to its superior stability in aqueous systems and higher reduction efficiency.
- These polymers offer a promising approach for treating dye-contaminated wastewater.
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