Estudo da capacidade de remoção do fármaco ciprofloxacina pelo processo de eletrocoagulação em um contexto de otimização, baixo consumo energético e redução da toxicidade

Abstract

To achieve the best removal capacity for ciprofloxacin (CIP), one must consider the existence of a series of parameters related to the operation of the electrocoagulation reactor (EC) and the intrinsic characteristic of the effluent to be treated, whose effects must be evaluated. From previous research, the importance of the electrical conductivity of the medium, be it a synthetic or real effluent, for the control and response of the total electrical voltage when the reactor is operated in constant electrical current density mode was highlighted. Based on preliminary tests, the joint effects of the parameters were evaluated, and these results served as a basis for the proposal of a more consistent experimental design, of the DCCR type, in addition to defining the treatment time with the best relationship between the maximum removal of pollutants and minimal energy consumption. For this purpose, an EC batch reactor with an effective area of 0.11 m² was built and operated at constant electric current density, using 1 mm thick iron plates. Drug removal was evaluated using total organic carbon (TOC) and high-performance liquid chromatography (HPLC) analysis. A three-stage process integration strategy, to employ electrocoagulation in a batch system with different electrodes, was proposed. The first stage consisted of the application of EC with iron electrodes (EC-Fe) and the efficiency in the response regarding the reduction of CIP was reached in the order of 70% and approximately 60% for the TOC, when using the experimental conditions considered better from the experimental design, the electrical conductivity of 6 mScm-1 and electric current intensity of 5 A (45.45 Am-2), with 20 minutes of electrolysis. As a second treatment step to remove CIP, the iron electrodes were replaced by aluminum electrodes to reduce the highly alkaline pH of the solution. This result was effective since at the end of this stage the pH of the treated solution remained in the order of 5.5 and the removal of CIP and TOC increased to 80% and 65%. In the last stage, the need for an efficient process to remove the remaining pollutants was observed, in this context, electro-Fenton was added to the treatment strategy, finding excellent results for the reduction of the concentration of CIP (≈100%) and of TOC (≈80%) and the visible reduction in toxicity, evidenced by the increase in the median lethal concentration to 80%, it can be stated that the proposed strategy proved to be efficient.