Use of waste Japonochytrium sp. biomass after lipid extraction as an efficient adsorbent for triphenylmethane dye applied in aquaculture

Comprehensive processing of Japonochytrium sp., one of marine fungi considered as a perspective source of functional lipids, was tested as an example of circular economy. Residual biomass after extraction of lipids (omega-3 polyunsaturated fatty acids and triacylglycerols) was magnetically modified using methanol suspension of microwave-synthesized magnetic iron oxides and tested as a potential biosorbent for triphenylmethane dye, crystal violet, used in aquaculture. Employing a batch experimental setup, influence of pH value (3-9), incubation time (0-270 min), initial dye concentration (400-1000 mg/L) of crystal violet, and temperature (282.15-313.15 K) on adsorption efficacy was studied. Adsorption equilibrium data were analyzed and fitted to the Langmuir, Freundlich, and Sips isotherm models. The monolayer maximum adsorption capacity of magnetically responsive spent biomass was found to be 329.22 mg/g at 294.15 K. The adsorption process agreed best with the pseudo-second-order kinetic model, and thermodynamic studies showed an endothermic nature of adsorption.