Valorization of tannery wastes: Lipoamino acid surfactant mixtures from the protein fraction of process wastewater

Abstract

The first stages of the transformation process of hides into leather (beamhouse process) generate an important waste in the tanning industry, since a considerable fraction of solubilised proteins ends up in waste water with the corresponding increase in contamination parameters, especially when the process is carried out without hair recovery (hair-pulping process). The objective of this work was the valorisation of this waste (the separated protein fraction) which conveniently hydrolyzed to amino acid level constituted the starting material for the production of biodegradable surfactants.The lipoamino acid surfactants were obtained by acylation of the amino acids from the protein hydrolisate. These surfactants were characterized and their physico-chemical and biological properties evaluated. They exhibit very low cmc values (about 40 mg/L).These surfactants are readily biodegradable and present an aquatic toxicity significantly lower than many common commercial surfactants derived whether from renewable or petrochemical feedstock. The mixtures of surfactants obtained are able to form oil/water emulsions that remain stable for at least one year. The results obtained in this work confirmed that it is possible the production of biodegradable and efficient lipoamino acid surfactant mixtures from the protein fraction present in beamhouse process wastewaters. This study constitutes a promising approach for the reduction of the pollution load from industrial tannery wastes and its valorisation as raw material for the production of surfactants with excellent environmental properties and good technical properties.

Self‐Aggregation and Emulsifying Properties of Methyl Ester Sulfonate Surfactants

“…As expected, O/W emulsions are formed when a-MES is used. Differences in the refractive index between dispersed and continuous media confirmed that O/W dispersions were formed [46]. These surfactants are water soluble and form micelles and liquid crystals in aqueous solutions that can favor the formation of O/W dispersions as observed by optical microscopy.…”

“…Hoefer et al [44] reported that among MES surfactants used in the production of synthetic materials, such as the polymerization of ethylenically unsaturated monomers, emulsifiers composed of a 22:88 mixture of disodium sulfolaurate and sodium sulfo methyl laurate formed emulsions that were more stable than emulsions obtained from n-dodecylbenzenesulfonate. In the present study, the surfactants were first [45,46]. During the emulsification, the emulsifiers adsorb at the oil-water interface, thereby reducing the interfacial tension while providing steric and electrostatic stabilization of the droplets.…”

“…These surfactants are water soluble and form micelles and liquid crystals in aqueous solutions that can favor the formation of O/W dispersions as observed by optical microscopy. Bancroft's rule states that the formation of more preferable emulsion types will occur in continuous phases where self-aggregation of the surfactant takes place [5,45,46]. Thus, in water, a-MES surfactants will tend to give O/W emulsions.…”

Lipoaminoacids Enzyme-Based Production and Application as Gene Delivery Vectors

“…LAAs that were obtained from naturally renewable sources could be produced by green-chemistry approaches, including biotechnological procedures, such as fermentation or enzymatic catalysis [31][32][33][34][35]. Protein hydrolysates from bioindustrial waste can also be used as a source of natural amino acids, allowing for the conversion of secondary products into high added-value compounds [36,37].…”

Amino Acid-Based Surfactants for Biomedical Applications

“…Natural amino acids are potential building blocks for surfactant synthesis due to their availability, biocompatibility, and multifunctionality [4][5][6]. Protein hydrolysates from waste proteins are ideal raw materials for the production of amino acid-based surfactants thus contributing to the valorization of secondary products, to the reduction of pollution load, and to the sustainable development of the bioindustry [7,8].…”