Simple Preparation of a Novel Poly(vinyl Alcohol)/Gallic Acid Adsorbent for Effective Removal of Methylene Blue from Aqueous Solution
2021
Gulyuz, Umit | Arslan, Mustafa
A novel bio-based polymeric adsorbent was fabricated and used for the removal of methylene blue (MB) from aqueous solutions. The method includes the synthesis of polymeric adsorbent from biocompatible chemicals such as poly(vinyl alcohol) (PVA) and 3,4,5-trihydroxybenzoic acid (gallic acid, GA) by using acid catalyzed esterification reaction. The obtained PVA/GA adsorbent was successfully characterized by the spectral, morphological, and thermal investigations using FTIR, SEM, DSC, and TGA. In the batch experiments, the adsorption performances of PVA/GA for MB were systematically investigated at various dye concentration, pH, contact time, and temperature conditions. The adsorption capacity of the PVA/GA reached a maximum value of 633.3 mg g⁻¹ at 25 °C. Possible reasons for high adsorption capacity of PVA/GA may be that the porosity and functional groups of PVA and GA afford sufficient active spots to advance the affinity of MB to the surface of adsorbent. The reusability efficiency of the adsorbent maintained above 96% after four adsorption–desorption cycles. In the data of adsorption process, it was most consistent with the Langmuir isotherm and pseudo-second-order kinetic models. Furthermore, it was confirmed that the adsorption is spontaneous and favorable from the thermodynamic point of view. The results demonstrated that the low-cost PVA/GA adsorbent system is simple to prepare and operate and exhibits promising properties as a reusable adsorbent for removal of hazardous dyes from aqueous solutions.
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