Abstract
Due to the existence of new methodologies that have reduced the production costs of microbiological chitosan, this paper puts forward the use of agro-industrial residues in order to produce microbiological chitosan and to apply chitosan as an innovative resource for removing acid orange 7 (AO7) from wastewaters. The best culture conditions were selected by a full 24 factorial design, and the removal of the dye was optimized by a 23 central composite rotational design. The results showed that corn steep liquor (CSL) is an agro-industrial residue that can be advantageously used to produce microbiological chitosan with yields up to 7.8 g/kg of substrate. FT-IR spectra of the product showed typical peak distributions like those of standard chitosan which confirmed the extracted product was chitosan-like. The efficiency of removing low concentrations of AO7 by using microbiological chitosan in distilled water (up to 89.96%) and tap water (up to 80.60%) was significantly higher than the efficiency of the control (chitosan obtained from crustaceans), suggesting that this biopolymer is a better economic alternative for discoloring wastewater where a low concentration of the dye is considered toxic. The high percentage recovery of AO7 from the microbiological chitosan particles used favors this biopolymer as a possible bleaching agent which may be reusable.
Highlights
Among the polymers most investigated today, there is chitosan, a polysaccharide formed by glycosidic amino residues of β-(1-4)-2-amino-2-deoxy-D-glucopyranose, which is obtained by deacetylation of α- or β-chitin found mainly in the shells of crustaceans and mollusks, respectively [1], or by the specific action of the enzyme chitin deacetylase (EC 3.5.1.41) on the residues of γ-chitin present in the cell walls of fungi [2,3,4]
The corn steep liquor (CSL) which was used as the sole source of carbon and nitrogen in batch positively influenced the microbiological production of chitosan
The microbiological chitosan used in the coagulation-flocculation experiments was obtained from S. racemosum grown in the best condition selected by the full factorial design described in Table 2 and used without purification
Summary
Among the polymers most investigated today, there is chitosan, a polysaccharide formed by glycosidic amino residues of β-(1-4)-2-amino-2-deoxy-D-glucopyranose, which is obtained by deacetylation of α- or β-chitin found mainly in the shells of crustaceans and mollusks, respectively [1], or by the specific action of the enzyme chitin deacetylase (EC 3.5.1.41) on the residues of γ-chitin present in the cell walls of fungi [2,3,4]. Obtaining chitosan from α-chitin requires some care regarding standardizing the product [12,13] and incorporating this biopolymer into production lines of different biotechnological areas This method of obtaining chitosan has adverse environmental implications as it produces millions of gallons of acidic and basic residues, which are discharged into the environment, usually without treatment and without a view to re-use [14]. Given this situation, obtaining chitosan by submerged culture of fungi has the advantage of manipulating and standardizing specific physicochemical characteristics, facilitating its incorporation into industrial production lines, besides helping to reduce the environmental waste generated when producing chitosan from the deacetylation of α-chitin [11,15,16]. Despite there already being extensive knowledge of the mechanisms of interactions between chitosan and azo dyes, this study innovates by applying a 23 Central Composite Rotational Design (CCRD), with four central points, to evaluate the simultaneous effect of chitosan concentration, dye concentration and pH on effluent decolorization by coagulation-flocculation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
