Keratin/Hydrotalcites Hybrid Sponges as Promising Adsorbents for Cationic and Anionic Dyes

Abstract

In this work, keratin sponges were prepared by freeze-drying method and tested for adsorption of Azure A and Methyl Orange dyes. The obtained materials showed a porosity of 99.92% and a mean pore size dimension of about 91 µm. The use of oxidized sucrose with a heating treatment at 150 • C was demonstrated to be a useful crosslinking procedure alternative to the conventional glutaraldehyde. Keratin sponges showed a maximum adsorption capacity of 0.063 and of 0.037 mmol/g for Azure A and Methyl Orange, respectively. The absorption of the cationic dye Azure A onto keratin sponges was better described by Freundlich model while the isotherm adsorption of the anionic Methyl Orange was found to correlate with both Langmuir and Freundlich models. The mean free energies evaluated by using the D-R model indicated a physisorption of Methyl Orange and a chemisorptions of Azure A onto keratin sponges. Finally, the functionalization of keratin sponges with Zn Al hydrotalcites nanoparticles did not affect the adsorption performances of the adsorbent toward the cationic dye Azure A, while it improved those toward the anionic Methyl Orange, increasing the related removal efficiencies from 43 to 96%. Collectively, the reported data indicates that the combination of keratin with hydrotalcites nanoparticles is a good strategy to obtain more functional adsorbent materials of potential interest for water treatment and purification.

Preparation Methods and Functional Characteristics of Regenerated Keratin-Based Biofilms

“…Postai et al [ 118 ] prepared a keratin porous sponge film by freeze-drying. To improve the insolubility of the keratin porous sponge film for application in water treatment, oxidised sucrose was used as a cross-linker.…”

“…Modified keratin has shown strong adsorption capacity for the metals As, Cd, Cu, V V , K, Co, Ni, Zn, and Cr VI [ 156 ]. Toxic water pollutants, such as heavy metals, dyes, and antibiotics, can be fixed in the network structure of the keratin-based film through complex reactions [ 118 , 157 , 158 , 159 ]. Qian et al [ 160 ] prepared a cellulose nanocrystal (CNC)/keratin composite film and investigated its blue KN-R dye adsorption behaviour.…”

Valorization of Livestock Keratin Waste: Application in Agricultural Fields

“…Wool keratin hydrolyzed by NaOH has been used to prepare keratin/polyamide 6-blend nanofibers, which have a high Cr 6+ adsorption capacity of over 55.9 mg·g −1 [ 11 ]. The AzureA and Methyl Orange maximum adsorption capacities of wool keratin/hydrotalcite hybrid sponges were reported as 0.20 mmol·g −1 and 0.04 mmol·g −1 at room temperature and neutral pH, respectively [ 140 ]. The Pb 2+ adsorption capacity of polyacrylic acid/wool keratin (product from reduction method) hydrogel can reach 234.60 mg·g −1 at 25 °C and at a pH of 4.…”

Adsorption Studies on the Removal of Anionic and Cationic Dyes from Aqueous Solutions Using Discarded Masks and Lignin

“…Nowadays, many in-depth studies have been conducted on various treatment techniques for dye removal, such as biodegradation, membrane filtration, adsorption, oxidation, flocculation precipitation, ozone oxidation, chemical precipitation, catalytic degradation, etc. [10][11][12]. However, most of the above methods are subject to limitations and are incapable of achieving the complete removal of dyes from wastewater.…”