Have you ever given a second thought to the orange rinds or coffee grounds you throw out, or perhaps the waste produced from our agricultural industries? Emenike says he has developed an environmentally friendly and cost effective way of using organic compounds like these to help recycle batteries.
This solves one of the key challenges of battery recycling, which is balancing cost against environmental impact. “There are different perspectives for recycling. One of them is to save the environment, which I think is really important, but the other purpose is also to make money from these materials. Sometimes these two goals can conflict, where it might be much cheaper to use toxic chemicals for recycling the batteries, or on the other hand you can use organic chemicals for recycling, but these can be more expensive.”
Using organic compounds from waste materials — such as sugarcane molasses and spent coffee grounds — is one of the ways Emenike proposes to tackle this challenge. “These organic compounds are biodegradable and will not have a negative effect on the environment. They are also making use of materials we are just throwing away,” he says.
While different methods can be used to extract the metals from the spent batteries, Emenike says he has developed a method that uses waste materials as an alternative to conventional reducing agents. “Reducing agents essentially reduce the oxidation state of the transition metals in the battery, aids their dissolution and improves the overall efficiency of the extraction process,” he says. “Spent coffee grounds, which are often tossed away by cafes, are very effective as reducing agents.”
Similarly, rather than using common acids such as sulphuric acid, phosphoric acid, nitric acid and hydrochloric acid, which are known to harm the environment, Emenike’s research proposes the use of organic acids such as citric acids, ascorbic acid, methanesulfonic acid among others. Some of these acids can even also be found in waste materials, such as citric acid in orange rinds. “These organic acids are biodegradable and less corrosive. Compared to acids such as sulphuric acid, the use of organic acids reduces the chemical and energy requirements in later steps within the recycling process," Emenike says.