Organic-Inorganic Hybrid Materials: Layered Double Hydroxides and Cellulose Acetate Films as Phosphate Recovery

With demand increasing for phosphate recovery, a considerable share of current research is dedicated to elaborate multifunctional materials. In this way, the objective of this work was to produce hybrid films from the combination of cellulose acetate (CA) biopolymer and magnesium and aluminium layered double hydroxides (LDHs) and investigate their performance for phosphate recovery. In this work, the following materials were prepared and characterized: LDH, calcinated LDH (LDH-c), CA film (CAF), CA film with LDH (CAF-LDH) and CA film with LDH-c (CAF-LDH-c). The produced materials were characterized by X-ray diffraction, thermogravimetric analysis coupled with differential scanning calorimetry and mass spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy and scanning electronic microscopy. The thickness, H₂O absorption (AH2O), stability in H₂O and phosphate adsorption of the produced films were evaluated. The adsorption capacity of films was compared to LDHs in powder form. The CAF-LDH and CAF-LDH-c increased film thickness, where CAF-LDH-c was thicker than CAF-LDH. CAF-LDH-c had higherAH2O than the other films, because of its increased thickness and mainly because of the H₂O sorption process of these materials. H₂O stability of 98.97% for CAF-LDH and 96.81% for CAF-LDH-c suggest the produced films can maintain their structural properties even after a long contact period with aqueous solutions. For the CAF-LDH-c, the maximum adsorption capacity of phosphate, according to the Langmuir-Freundlich model, was 6.98 mg/g. The adsorption value suggests that this film can be used as an efficient phosphorus (P) adsorbent from wastewater or a eutrophicated source.