This is a protocol for determining the pH-dependent adsorption of chemicals by biochar. The resulting product is a plot of adsorbed concentration, or adsorbed fraction of added sorbate, as a function of pH. These plots are typically referred to as "adsorption edges" for cations or "adsorption envelopes" for anions. In cases where the exact adsorption mechanism is unknown, the general term "sorption" is substituted for "adsorption". Variables such as initial sorbate concentration, ionic strength of the background solution, and biochar:solution ratios need to be considered beforehand for the results to be practically useful.
The reagents, concentrations, and reaction times in this protocol will refer to those detailed in Padilla et al., (2024). However, there is much flexibility with these variables, so please see the "Guidelines & Warnings" tab before starting.
Padilla, J.T., Watts, D.W., Szogi, A.A., Johnson, M.G. (2024). Evaluation of a pH- and time-dependent model for the sorption of heavy metal cations by poultry litter-derived biochar. Chemosphere 347, 140688.