Adsorption of dirty dozen chemicals (DDCs) from water: A comprehensive review

Due to their long-term environmental persistence and propensity to cause serious health issues, “dirty dozen” chemicals (DDCs) are a big concern when found in marine environments. With the urgent need to remove them from water, this work presents an extensive evaluation of the adsorption technique for removing DDCs from aqueous environments. From review, the physicochemical characteristics of the adsorbent, the pH of the solution, and the DDCs property are the key factors that affect adsorption chemistry. The highest reported adsorption capacity for DDCs is 967 mg/g for H₃PO₄ activated carbon derived from wood observed in the removal of 2-monochlorinated biphenyl. The key mechanisms for DDCs uptake was observed to be complexation, π-π interactions, hydrophobic contacts, electrostatic interactions, hydrogen bonding, and pore filling. Most DDCs uptake is favoured in the neutral pH range which is ideal for potential scaled-up operations as acidification can have significant cost implications. DDCs are efficiently eluted from spent adsorbents using organic solvents (ethanol, methanol and hexane) and most adsorbents are reusable for 3–10 cycles. Future studies can focus on developing a better understanding of the cost performance of adsorption for DDCs removal, an area not fully explored currently. It is surmised that adsorption is ideal for DDCs removal and avenues for scalable application of the technology to be explored.