Waste waters generated in industries and homes have a combination of negatively (anionic) and positively (cationic) charged species. A material called activated carbon is often used to get rid of these contaminants. The commonly used Aquaguard too uses activated carbon. Several RO-UV (short for "reverse osmosis-ultra violet") also use activated carbon. The problem is that this material is a bit too expensive, since its manufacture involves vacuum techniques. Hence it is desirable to come up with alternate materials (called adsorbents), which would be able to adsorb (immobilize) both anionic and cationic contaminants.
In this study, we focus on anionic (Congo Red, Orange G) and cationic (Methylene Blue, Malachite Green) dyes which are widely found in effluents from textile, leather, fishery, and pharmaceutical industries. Their carcinogenic (cancer causing), mutagenic (mutation causing), genotoxic (gene disrupting), and cytotoxic (cell death inducing) impact on mammalian cells is well-established. Remember human beings are mammals too! Hence these dyes, beyond a certain minimal concentration, harms you and me.
We show that combining ZnO, (Zn0.24Cu0.76)O and cobalt ferrite to make an "adsorbent bed" works well. This system efficiently adsorbs the model anionic and cationic pollutants. This adsorbent system works well even when complex mixtures of these pollutants is used. All adsorbent phases are synthesized using room temperature, high yield (~96-100%), green chemical processes. This makes the process eco-friendly and economically viable.
In this paper, we do a comprehensive analysis of the thermodynamics and kinetics involved in the adsorption process. We also study the material properties that are responsible for the observed adsorption behavior.
PS: Niya presented a poster at the Royal Society of Chemistry's Water Quality workshop (Aug 13-14, 2013 in Bangalore). The poster she presented can be found here. This poster contains a brief over view of our work on both photocatalysts, and adsorbents.
