Improving Spent Coffee Biochar for Effective Organic Contaminant Removal from Aqueous Media

The contamination of (waste)water with organic pollutants, such as pharmaceuticals and dyes, is drastically increasing. Their removal process presents several difficulties, and often activated carbon (AC) is used in a filtration step. While commercial AC is often based on fossil resources, in this study, we present a new approach toward biochar from spent coffee (SC). This new AC has considerably enhanced surface areas and porosities, making it suitable for wastewater treatment. Using MgCO₃ as an activating agent, a biochar with a significantly enhanced surface area of ∼600 m²/g is produced in a simple but efficient manner. The resulting biochar is effective for the removal of a whole spectrum of organic pollutants in aqueous systems. The dyes methylene blue (MB) and methyl orange (MO), but also the pharmaceuticals diclofenac (DCF) and tetracycline (TET), as well as the xenoestrogen bisphenol A (BPA), are successfully removed by up to 100% from aqueous solutions with the new adsorbents. Removal efficiencies depend on the pH of the solutions. In contaminant mixtures, the biochar shows preferences for adsorption toward some compounds but still shows very high adsorption capacities for all contaminants.