Abstract
Poly(acrylamide co-acrylic acid) hydrogels were prepared by free-radical copolymerization of acrylamide and acrylic acid in aqueous solutions using electron beam irradiation in the dose range of 2.5 kGy to 6 kGy in atmospheric conditions and at room temperature. The influence of the absorbed dose, the amount of cross-linker (trimethylolpropane trimethacrylate) and initiator (potassium persulfate) on the swelling properties and the diffusion coefficient and network parameters of hydrogels were investigated. The structure and morphology of hydrogels were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The use of the obtained hydrogels by the removal of Cu2+ and Cr6+ from aqueous solutions was investigated at room temperature. During the adsorption of metal ions on hydrogels, the residual metal ion concentration in the solution was measured by an atomic absorption spectrophotometer (AAS). It has been established that the use of a relatively small amount of trimethylolpropane trimethacrylate for hydrogel preparation has led to the increasing of swelling up to 8500%.
Highlights
Heavy metal ions are harmful and toxic to human beings and the environment
The poly(acrylamide co-acrylic acid) hydrogels were prepared by free-radical copolymerization of acrylamide and acrylic acid in aqueous solutions using electron beam irradiation in the dose range of 2.5 kGy to 6 kGy in atmospheric conditions and at room temperature
The Measurement of Gel Content where W 0 is the initial weight of the dried sample and W 1 is the weight of sample after extraction from the waterThe andhydrogel drying. content of a given material is estimated by measuring its insoluble part in dried samples after immersion in water
Summary
Heavy metal ions are harmful and toxic to human beings and the environment. They must be removed from wastewater and drinking water. Heavy metals are very toxic and non-biodegradable; they can readily be accumulated in an ecological system, induce irreversible pollution, or cause adverse health effects in the human body [3]. Because they are non-biodegradable and can accumulate in the food chain, heavy metal ions from industrial effluents seriously threaten the environment and public health, even at very low concentrations [4,5,6]. Some widespread methods for removing heavy metals include chemical coagulation and precipitation [8,9], membrane filtration [10,11], ion exchange [12,13] and Materials 2017, 10, 540; doi:10.3390/ma10050540 www.mdpi.com/journal/materials
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