Abstract: Provided are methods and structures for adsorbing contaminants from liquid, and applications thereof. An adsorbing mixture comprised substantially of rice hull ash is added to a liquid with contaminants that is at a preferred temperature for the adsorbing mixture. The adsorbing mixture interacts with the liquid with contaminants for a preferred amount of time and adsorbs the contaminants such that the contaminants are removed from the liquid. The adsorbing mixture is removed from the liquid using a filter that separates the adsorbing mixture from the liquid by way of a preferred pore size that allows the liquid to pass through but not the adsorbing mixture.