Fabrication of impregnated activated carbon promoted by iron nitrate and its application for adsorptive removal of organic matters from actual reverse osmosis concentrate

In this study, the potential of a highly efficient composite of activated carbon with iron oxide active substances was explored for removing organic matters from reverse osmosis concentrate. The water quality characteristics indicated that the organic matters were mainly small molecular with molecular weight less than 1 kDa, and composed of hydrophilic-alkali, hydrophilic-neutral and hydrophobic-neutral substances. The specific surface area of the activated carbon composite was 482.96 m2/g, with 91.97% of the total specific surface area being microporous. Iron oxide active substances was loaded on activated carbon skeletons, mainly forming Fe2O3 and Fe3O4. The adsorption process was fitted with pseudo-second-order and Langmuir isotherm models, with the active site playing an important role in the adsorption capacity and the adsorption was spontaneous and endothermic. Combined with the refractory characteristics of the wastewater quality, electrostatic interactions, hydrogen bonding and functional group complexation were the main forces involved in the adsorption process, taking into account the refractory nature of the wastewater.