Removal of Acid Violet 7 (AV7) Dye from Aqueous Solutions Using Modified MOF-5 Adsorbents

This study investigated the preparation and modification of MOF-5 for the removal of acid violet 7 (AV7) dye. One type of waste-derived siliceous material, i.e., rice husk ash (RHA), was used in different ratios to create modified MOF-5 adsorbents. From preliminary studies, it appears that MOF-5, modified with RHA-1000, has significant potential for the removal of the AV7 dye. Using Taguchi optimization approach, the optimum adsorbent for the removal of AV7 dye from aqueous solutions was found to be MOF-5/RHA-1000/(2:2:2). The study also investigated the factors influencing the removal of AV7 dye by the modified MOF-5 adsorbent. The optimum initial dye concentration, shaking rate, temperature, pH, amount of adsorbent and contact time for effective AV7 dye adsorption were 85 mg/L, 250 rpm, 50 °C, 9, 0.4 g and 4 h, respectively. The results showed that the Temkin isotherm model and the pseudo-first order model gave excellent agreement with the experimental conditions. The study further demonstrated that the adsorption of AV7 dye onto modified MOF-5 is a non-spontaneous and endothermic process. The results of the SEM micrographs revealed a consistent and nearly uniform arrangement of pristine MOF-5, with cubic particles of similar size. The BET study indicated that the specific surface area was a factor influencing the effectiveness of AV7 dye adsorption. The FTIR analysis confirmed the successful formation of the pristine and modified MOF-5 framework and the presence of new peaks in the FTIR spectra of spent adsorbents indicates the successful adsorption of AV7 dye onto the MOF-5 adsorbents. The results demonstrate that modified MOF-5 adsorbents are effective for removing AV7 dye.