Biomass-based adsorbents for wastewater remediation: A systematic review on removal of emerging contaminants

As anthropogenic activities, industrialization, and technology have grown exponentially in recent decades, the presence of emerging contaminants (ECs) is increasing stress on fresh and sustainable water supplies due to their environmental toxicity. Therefore, a holistic approach is urgently required for the development of efficient technologies to bring the idea of wastewater remediation to fruition. Adsorption with biomass-based adsorbents can contribute to this perception as it offers numerous advantages over existing wastewater treatment technologies. This review ensures a thorough analysis of the potential application of natural sustainable adsorbents based on biomass for efficient removal of ECs including pharmaceuticals and personal care products (PPCPs), agrochemicals, aromatics, and microplastics (MPs). Various factors impacting the adsorption efficiency such as adsorbent dosage, concentration, contact time, pH, and temperature, along with the best-fitted models have been provided for the critical literature analysis. The adsorption mechanism involved was reviewed based on the point of zero charges of adsorbents, the ionic form of adsorbate, the hydrophobicity of adsorbate and adsorbent, surface functional groups, etc. Further, literature gaps were also identified and discussed for directing future research needed in the development of inexpensive, eco-friendly, efficient, reusable adsorbents with the overall process based on circular bio-economy and 4R (Reduce, Recycle, Re-use and Recover) approach, so that it can be commercialized to promote more sustainable futures.