Using magneto-adsorbent for methylene Blue removal: A decision-making via analytical hierarchy process (AHP)

Uncontrolled release of dyes from industrial effluents have led to significant environment pollution. Thus, it is crucial to develop an effective strategy to remove dye molecules from water resources. Over the past few decades, researchers have been investigating the feasibility of using Fe3O4 nanoparticles, natural polymer beads, Fe3O4-encapsulated natural polymer beads and other types of magneto-adsorbents for dye adsorption. Most of the results demonstrated that the dye removal efficiency attained by these adsorbents is promising. However, problem arises when comes to the final decision to select the most suitable adsorbent for industrial implementation. In fact, there has been no systematic comparison performed among different types of adsorbents. Hence, this case study aims to analyse the most suitable type of magneto-adsorbent for methylene blue removal based on a structured analytical hierarchy process (AHP). First, an AHP model was developed via multi-level of objective. The criteria involved in the decision-making were the adsorption capacity, the ability to conduct Fenton degradation, the potential side effect, the adsorbent cost, the energy consumed, and the required downstream separation process. Our analysis implied that Fe3O4 is best to be used for methylene blue removal at its bare condition (i.e without any modification/encapsulation). Here, bare Fe3O4 was found to score higher global priority (0.303) than the modified/encapsulated counterparts owing to its excellent local weight in the dominant criteria.