Aplicação de processos oxidativos avançados visando a redução de cor do caldo de cana-de-açúcar variedade RB-92579

Abstract

Phenolic substances are responsible for giving color to the sugarcane juice. Its removal in the broth clarification stage, which occurs after milling, makes a broth clear and the sugar of origin, becomes whiter and of greater commercial value. The sulfitation process, which is applied for this purpose, provides barriers to the commercialization of white crystal sugar, due to the sulfur residues present above the limits of the laws in force in the international market. In this study, aiming to present alternatives to clarifying the sugarcane juice, Advanced Oxidation Processes (POAs) were studied. The sugarcane variety RB-92579 was used, due to its greater productivity in the field, and its industrial limitation due to the high color of the juice. The experiments by POA maintained the operational conditions of the broth clarification stage of the industrial process: temperature around 100 oC and pH between 6.8 to 7.2, corrected with calcium hydroxide solution. A dosage of 0.75 molL-1 of hydrogen peroxide was applied, in addition to exposure to ultraviolet light. The experiments took place in batch mode and in a continuous regime in glass reactor in two configurations: closed reactor without mirror and open reactor internally mirrored. For the treatment of the broth by electrolysis, DSA® electrodes with titanium metal base, coated with ruthenium oxides and titanium oxide, were used, with current densities of 10, 20 and 30 mA / cm2 being applied. And Ca (OH) 2 solution was used to correct the pH of the raw broth. As a result, a reduction of 65% in ICUMSA color was obtained by applying the treatment by POA, in batch experiments and in those carried out in a closed reactor without a mirror. The photolysis of hydrogen peroxide, at 0.75 molL-1 by irradiation of 85 Watts of ultraviolet light applied in an open reactor and mirrored internally, reduced the ICUMSA color of the broth by 85%. The experiments carried out by electrodegradation with a current density of 20 mA / cm2 showed greater efficiency in removing the color from the sugarcane juice (90%), in a time of 90 minutes. The results demonstrated that the applications by Advanced Oxidative Process by photolysis of hydrogen peroxide and Electrolytic Process by electrodegradation, can be alternatives in substitution to the process by sulphite, adding greater value to sugar.