Synthetic Hydrogels and Their Impact on Health and Environment

Abstract

Hydrogels have been discovered nearly 60 years ago and due to their permeability to water systems, they have become very important materials for use in comparison to other polymers. Hydrogels are materials first rationally designed for use in human medicine, and they find important usage in various areas, for example, in products for personal care, pharmaceutical, agriculture, and environmental protection. Especially interesting is the class of stimuli-sensitive hydrogels, due to their properties to respond to changes in pH, temperature, and ionic strength of the surrounding medium, whereby changes exist in the network structure, for example, swelling properties. Hydrogels have significant applications: in diagnosis, as substrates or implants in tissue engineering, as drug delivery carriers, and in cosmetics. Water pollution by heavy metals and dyes is a major environmental problem because of toxicity to the living world, bioaccumulation, and bio-non-degradability. Adsorption of heavy metals, radioactive elements, and dyes using the hydrogels is an effective way for their removal. The mechanism of heavy metals and dye ions removal using hydrogels could be explained by the physical adsorption, hydrogen bonding, complexation, and/or chelation and ion exchange. The pollutants adsorption process using hydrogels has some important advantages compared to conventional techniques: high adsorption capacity for removal of pollutants from aqueous solutions, binding ability, and reusability (regeneration). Hydrogels have applications in some systems for the controlled and sustained release of pesticides and fertilizers, so reducing the contamination of the soil and surface water by these agrochemicals.