Abstract
The polyethyleneimine (PEI) based hydrogels in different morphology and sizes such as bulk, micro and cryogels were synthesized, and used in various environmental applications. Additionally, the synthesized PEI based hydrogels, microgels, and cryogels were used as template for in situ metal nanoparticles such as Co, Ni, and Cu to generate PEI-M (M: Co, Ni, Cu) composite materials. Then these PEI-M composite hydrogels (bulk, micro and cryo) were used as catalysts in the hydrolysis of NaBH4 for H2 generation (clean energy source), and in the reduction of toxic nitro compounds such as 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP) to their more useful corresponding amino phenols, respectively. Various kinetic and activation parameters such as hydrogen generation rates (HGR), turnover frequencies (TOF), and activation energy (Ea), enthalpy (ΔH) and entropies (ΔS) were calculated for H2 production and nitro compound reductions. Furthermore, the PEI-Cu composite hydrogels used for degradation of organic dyes such as Methylene Blue (MB) and Eosin Y (EY) in different aquatic environments such as distilled water (DI), tap water seawater, and creek waters. Different from those, the PEI based bulk, micro, cryogel were also shown to ve very effective in the removal of toxic metal ions anions such as arsenate (AsO43-), chromate (CrO42-), dichromate (Cr2O72-). Absorption parameters of these tedious, and toxic metal ions were investigated to define the nature of toxic anions by applying Langmuir and Freundlich isotherms. The morphological, structural, thermal and characterization PEI based hydrogel (bulk, micro and cryo) and their metal nanoparticle containing composites were done using SEM, FT-IR, TGA, TEM and AAS measurements. It was found that PEI based hydrogels possesses tremendous potential in the environmental applications for the removal and eliminations of toxic aromatic nitro compounds and organic dyes as well as tedious toxic metal ions such arsenic and chromium.