Title : Selective adsorption capacity of grape marc hydrogel for adsorption of binary mixtures of dyes
Abstract:
In this work, an aqueous solution containing industrial dyes consisting of methylene blue (MB), and methyl red (MR) was treated with bio-oxidize grape marc entrapped or not in calcium alginate hydrogels. Experiments were carried out in batch, a room temperature using different concentration of adsorbents and dyes. When dyes were evaluated separately, non-immobilized grape marc hydrogel was unable to remove any MR whereas when the bioadsorbent was immobilized in calcium alginate beads the removal of MR was around 88%. Contrarily, 98% of MB was removed with both, nonentrapped or entrapped grape marc. Regarding binary mixtures, it was observed that the adsorption of MR was not affected by the presence of MB, whereas the adsorption of MB decreased in high extend on nonentrapped grape marc when MR was present.
Adsorption conditions were optimized for binary mixtures using a Box-Behnken factorial design, obtaining theoretical equations that allowed to calculate the removal percentage and capacity of calcium alginate-grape marc hydrogel depending on the concentration of dyes (40–100 mg/L), ratio between bioadsorbent and water stream (0.6–1.2) and adsorption time (10–60 min). The equations obtained revealed that grape marc hydrogel is able to remove 100.0–93.3% of MB and 78.72–57.80% of MR in 10 min in the range of dye and bioadsorbent stablished in the experimental design, being the extraction time the less significant variable. Additionally, the kinetic study showed that pseudo-second-order was the model that better explained the bioadsorption process for both dyes in binary mixtures onto grape marc hydrogel
Audience Take-Away:
The main objectives of this work were:
- Evaluate the selective adsorption capacity of two synthetic dyes, methylene blue (MB), and methyl red (MR), from aqueous solutions, on an eco-friendly bio-adsorbent based on biodegraded grape pomace.
- Evaluate the influence of calcium alginate beads on the removal efficiency of the two synthetic dyes and the possible interaction between the two dyes in a binary mixture.
- Obtain validated theoretical equations that predict the adsorption of binary mixtures under different concentrations of dyes and bio-adsorbent.
- Evaluate the kinetic behavior during the adsorption of the dyes on the calcium alginate-grape pomace hydrogel, in binary mixtures, by applying different kinetic models including pseudo-first order, pseudo-second order, Chien-Clayton and intraparticle diffusion.
