Extraction characterization and application of bio-coagulant for treating dyes containing solution using aristeus antennatus and aristaeomorpha foliacea red shrimps

Abstract

Chitosan is a biopolymer having huge possibilities when it comes to chemical and mechanical structural changes. These physicochemical properties confer to the polymer numerous areas of applications, in particular in the area of water treatment. From the environmental point of view, this will result in a much lower risk of toxicity for the treated waters. In addition, the sludge produced would be in lesser quantity, with a better biodegradability and a low metal content. Shells of red shrimp (Aristeus antennatus and Aristaeomorpha foliacea) fished locally 45 km to the west of Algiers, were used as raw materials for the extraction of chitosan by deproteinization, demineralization and deacetylation. The final product was characterized by different methods (FTIR, potentiometric titration, SEM, DRX); the deacetylation degree of chitosan was found to be around 75%, which was compared in the rest of this study with commercial chitosan at 95% deacetylation degree. In most cases, this polymer is used as adsorbent in its solid form, but it can also be used in the dissolved state in the coagulation-flocculation process. This work is concerned with the use of dissolved chitosan for the removal of sulfonated azo dyes. Amongst the important parameters affecting the coagulation-flocculation process are the coagulant dose and the initial pH. The best removal rates were found to be between 50% and 55% in acidic media around pH 3. The dye coagulation mechanism appears to be governed by charge neutralization. The dye sulfonic groups being attracted to protonated amino groups of chitosan in the colored solution.

Keywords: Red shrimp, chitosan, characterization, coagulation-flocculation, sulfonated azo dyes