Date palm waste biochar for the adsorptive removal of pharmaceuticals: a review

Over the past decade, pharmaceuticals have emerged as a significant class of environmental contaminants due to their adverse impacts on natural ecosystems. The removal of pharmaceuticals from aquatic environments, soils, and wastewater treatment systems using techniques such as adsorption, advanced oxidation, biological degradation, and membrane filtration has been widely investigated. Among these approaches, adsorption attracted considerable attention due to its simplicity, high removal efficiency, and low energy requirements. Date palm waste biomass is abundant biomass source what makes it a promising precursor for biochar and activated carbon adsorbents production for water treatment. This review critically evaluate the impact of the different date palm components, pyrolysis conditions, and activation methods on biochar properties and its performance as an adsorbent of emerging contaminates, particularly pharmaceuticals, from wastewater. Moderate pyrolysis temperatures (400–600 °C) found to generally enhance adsorption performance, while higher temperatures (≥ 700 °C) increase surface area but reduce surface polarity and affinity towards polar pharmaceuticals. Moreover, chemically activated biochars (H3PO4, KOH, or ZnCl2) exhibit an improved porosity and adsorption capacities, reaching 400 mg/g, that is comparable to commercial activated carbons. In contrast, physical activation (steam, CO2) is a more environmentally friendly approach that relatively increases surface area and pore volume, but shows limited improvement in adsorption capacity. Despite these advances in the literature, the relationship between specific date palm feedstock and adsorption performance remains insufficiently explored, highlighting the need for systematic comparative studies.