Trimethylamine Adsorption Mechanism on Activated Carbon and Removal in Water and Oyster Proteolytic Solution

In this study, seven coal-based activated carbons (ACs) were adopted to remove trimethylamine (TMA) in an aqueous solution as environmentally friendly and harmless adsorbents. The results showed that columnar AC (CAC) had a clear scale and honeycomb structures with few fragments and micropores, contributing to superior TMA removal capacity compared to granular AC (GAC) (71.67% for 6.0 mm CAC and 69.92% for 40 – 60 mesh GAC). In addition, the process of adsorption was accompanied by desorption, and the recommended absorbed time was 120 – 180 min. The short time to achieve equilibrium indicated that adsorption was kinetically controlled, and pseudo-second-order kinetics was more appropriate than pseudo-first-order kinetics in explaining the adsorption mechanism in both water and oyster enzymatic hydrolysate. The intraparticle diffusion model presented that the adsorption processes could be divided into three steps for GAC and two steps for CAC. The adsorption processes were consistent with the Freundlich model, indicating the existence of physisorption and chemisorption as multilayer adsorption. The results indicated that AC, especially CAC, has great potential for TMA elimination in aquatic product processing.