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Asked 24th Dec, 2013
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Can salt be used to activate charcoal / biochar?
I read an intriguing paper called 'Low-Tech Coconut Shell Activated Charcoal Production' by Cobb et al in the 'International Journal for Service Learning in Engineering', Vol. 7, No. 1, pp. 93-104, Spring 2012,ISSN 1555-9033. They found that salt led to activation of coconut shell charcoal, though it was only 1/6th of adsorptive capacity of commercial GAC. I repeated their experiment using a hard word charcoal and found similar results to Cobb et al. - the salt activated char removed twice as much of the methyl orange dye as the non-activated char. When adding salt, the char seems to froth and Stephen Joseph (Prof Emeritus, UNSW) suggested there may be concentration of chloride ions in the water layer just above the floating biochar particles as evaporation occurs. I'm trying to find a way of activating charcoal / biochar cheaply and safely for use in waste water clean-up in developing countries so this possibility of using salt rather than something like NaOH or steam seems appealing. So interested in experts' opinions on feasibility / reproducibility / pitfalls of this idea. Thanks v. much, Simon
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dear Miguel - if you send me your email i will send you a copy of the paper where I read about this. Other experts I've spoken to are not entirely convinced by the methodology the authors used. But worth exploring further. Gasification chars seem to work well as they have a higher surface area. I guess gasified coconut shell is ideal for water filtration.
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All Answers (5)
Dear Simon,
Salt could be potentially a good material for activation of your charcoal. you have also obtained good results in removing your reference dye. maybe you can try to check your activated charcoal with other pollutants as well and see how much improvement you can get in terms of adsorption capacity.
hi Babak - thanks for your response. Can you please recommend a pollutant for me to try? I'm doing the field work in Cambodia and some of the chemicals the farmers use in the rice fields are 2-4-D, glyphosate, validamycin A and malathion. My problem might well be in the lab analysis of the chemical concentration post-filtration so something that can be detected relatively easily would be better. All best, Simon
you can try Heavy metals or maybe other types of dyes such as Methylene Blue or reactive or basic dyes. they are easy to detect.
dear Miguel - if you send me your email i will send you a copy of the paper where I read about this. Other experts I've spoken to are not entirely convinced by the methodology the authors used. But worth exploring further. Gasification chars seem to work well as they have a higher surface area. I guess gasified coconut shell is ideal for water filtration.
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