doi:10.1038/nindia.2016.145 Published online 1 November 2016
Researchers have created activated carbons from red grape pomace that can remove heavy metals from industrial wastewater via an eco-friendly process1.
Activated carbons prepared from coal and petroleum products are expensive which pushes up the cost of wastewater treatment.
In search of a cheap alternative source, scientists from Dehradun-based Graphic Era University heated and dried chemically-treated ground red grape pomace, which is usually discarded as solid waste by wine-makers. They then assessed the efficiency of carbon-containing grape pomace in binding heavy metals from solutions that mimic metal-ion-polluted wastewater.
Thermal treatment formed irregularly shaped pores on the surface of the grape pomace, increasing its surface area. As well as forming activated carbons, the treatment destroyed the grape pomace polyphenols, which can contaminate treated water.
At pH levels of 4 and above, active sites on the surface of grape pomace gain negative charges and bind to positively charged heavy metals such as lead and cadmium through electrostatic attraction, increasing the adsorption of heavy metals from solutions.
Irrespective of metal ion concentration, the grape pomace showed fast adsorption of heavy metals in the first two hours, before slowing and reaching equilibrium after four hours.
1. Nayak, A. et al. Development of a green and sustainable clean up system from grape pomace for heavy metal remediation. J. Environ. Chem. Eng. 4, 4342-4353 (2016)