doi:10.1038/nindia.2016.67 Published online 27 May 2016
A nanocomposite that can remove toxic organic dyes by adsorbing them and breaking them down into inactive products by harnessing sunlight is potentially useful for treating industrial wastewater1.
While polymer-based nanocomposites can efficiently adsorb organic dyes, they cannot safely dispose the adsorbed dyes.
To develop a nanocomposite capable of both adsorbing and disposing dyes, researchers used titanium dioxide, gold nanoparticles and polymers to synthesize a nanocomposite. They then explored how efficiently this nanocomposite removed two organic dyes — methyl violet and acid orange — for various pH, adsorbent dosages and dye concentrations in the presence of sunlight.
The negatively charged surface of the nanocomposite favoured the adsorption of positively charged methyl violet. Increasing the pH, increased the adsorption of methyl violet and reduced the removal rate of negatively charged acid orange.
When exposed to sunlight, the nanocomposite degraded adsorbed methyl violet into inactive products, removing almost 90% of the adsorbed dye. It also efficiently degraded toxic dyes present in a textile effluent after being exposed to sunlight for 4 hours.
In addition, the nanocomposite inhibited the growth of Escherichia coli bacteria when illuminated by visible light from an artificial source.
“Since the nanocomposite can adsorb and degrade dyes by harnessing sunlight, it offers a solution for disposing of dyes that are potentially harmful to environment,” says lead researcher Sagar Pal.
The authors of this work are from: Polymer Chemistry Laboratory and Department of Applied Chemistry, Indian School of Mines, Dhanbad, and Discipline of Inorganic Materials and Catalysis, Central Salt and Marine Chemicals Research Institute (CSIR), Bhavnagar, Gujarat, India
1. Sarkar, A. K. et al. Efficient removal of toxic dyes via simultaneous adsorption and solar light driven photodegradation using recyclable functionalized amylopectin−TiO2−Au nanocomposite.ACS Sustainable Chem. Eng. 4, 1679−1688 (2016)