doi:10.1038/nindia.2013.109 Published online 21 August 2013
Researchers have developed new hydrogels that can remove toxic dyes such as Congo red and methyl violet from water . They produced these hydrogels by dissolving organic compounds such as acrylic acid and hydroxylethyl methacrylate in an aqueous solution of sodium alginate. Such hydrogels will be very useful for treating industrial effluents containing these toxic dyes.
Congo red is a commonly used dye in the textile industry. It is toxic to many organisms and is a potential carcinogen. Vast quantities of methyl violet are used for dyeing textiles and paper. Studies have shown that 15 per cent of such dyes are released into the environment via wastewater. Existing methods for disposing of these toxic dyes are not ecofriendly and involve complex processes.
To devise an easy, environmentally friendly way to remove the toxic dyes, the researchers synthesized hydrogels by mixing acrylic acid and hydroxylethyl methacrylate with an aqueous solution of sodium alginate. They used an organic compound to crosslink the hydrogels, producing an interpenetrating network of hydrogels.
They prepared aqueous solutions of Congo red and methyl violet and tested how effectively the hydrogels removed these dyes from water. Based on measurements of the swelling, diffusion and network parameters of the hydrogels, the researchers say that the hydrogels showed high adsorption of the two dyes from water.