New insight into the effect of layer-by-layer & in-situ growth of MOF on alginate vs preformed MOF mixed alginate composites on dye adsorption

Over the past years, the processing of metal-organic frameworks (MOFs) into body-shaped materials has received remarkable research interest to overcome the difficulties of using MOFs in powder form for advanced applications. In this work, shaped MOF-biopolymer composites are prepared from Iron (Fe), trimesic acid (BTC) for the MOF named Fe-BTC and sodium alginate as biopolymer using different strategies including the conventional mixed phases, the in-situ growth and layer-by-layer synthetic strategies to highlight the role of each method for the accessibility of active sites and determine which one is better for the adsorption capability. The obtained samples were characterized to reveal the interaction between the biopolymer and the MOF and subsequently tested for methylene blue dye adsorption to elucidate the effect of each strategy on the adsorption performance. The results indicated that the layer-by-layer synthetic strategy showed better accessibility for the active sites and thus an enhanced adsorption performance of the dye achieving 88.779 mg/g, surpassing the efficiency of the other strategies.