Removal of Azo Dyes Through a Natural Coagulant Obtained from Coffee Waste (coffea Arabica)

Abstract

The present work evaluated the performance of coffee (Coffea Arabica) Caturra variety waste extracts for the removal of two azo dyes used in the textile industry. Ultrasonic extractions were performed to evaluate the effect of particle size and type of residue on the concentration of polyphenols in the extracts, finding that the dehydrated pulp with a particle diameter of 3.375 mm is the residue with the highest yield with 6.96 ± 0.08 milligrams of Gallic Acid in a gram of dry base (mgGAE/gBD); The extract of polyphenolic compounds was dosed in synthetic waters with azo dyes to test its efficacy as a coagulant, using a jar test by varying the doses and pH. It was found that the maximum removal for the acid red dye was 59.37 % of the acid red dye #88 (RD-88) at a concentration of 15 milligrams per liter (mg/L) of the natural coagulant at acid pH and 49.76 % of the acid yellow dye #36 (YD-36) at a concentration of 15 mg/L of the polyphenolic extract at neutral pH. Finally, the results obtained were compared with the performance of aluminum sulfate (AS), which achieved a 65.44% removal of YD-36 at a concentration of 15 mg/L at neutral pH and 95.04% of RD-88 at a concentration of 10 mg/L of metallic coagulant at acid pH. natural coagulants obtained from coffee residues have the potential to be used in the removal of cationic dyes by coagulation processes, it is necessary to carry out tests to optimize the process and improve the coagulant by means of chemical modifications and the use of complementary flocculants.