A comprehensive review of coconut-based porous materials for wastewater treatment and CO₂ capture

For several decades, water pollution has become a major threat to aquatic and non-aquatic species, including humans. Different treatment techniques have already been proposed and implemented depending on wastewater characteristics. But many of these treatment techniques are expensive and inefficient. Adsorption-based techniques have shown impressive performances as an inexpensive treatment method previously. Coconut-based resources have been considered as adsorbents for wastewater treatment because of their abundance, low cost, and favorable surface properties. However, over the last decade, no comprehensive study has been published regarding biochar from coconut-based materials for wastewater treatment and CO₂ capture. This review discusses biochar production technology for coconut-based materials, its modification and characterization, its utilization as an adsorbent for removing metals and organics from wastewater, and the associated removal mechanisms and the economic aspects of coconut-based biochar. Coconut-based materials are cheap and effective for removing various organic compounds such as pesticides, hormones, phenol, and phenolic compounds from solutions and capturing CO₂ from air mainly through the pore-filling mechanism. Utilizing coconut-based biochars in a hybrid system that combines adsorption and other techniques, such as biotechnology or chemical coagulation is a promising way to increase their performance as an adsorbent in wastewater treatment.