Análise da secagem de sementes de mamão formosa (Carica papaya L.) utilizadas na adsorção do corante vermelho do congo

Abstract

The liquid industrial effluent, when released into receiving water bodies without treatment, causes serious environmental problems due to its load of contaminants. A typical contaminant in the textile industry are the azo dyes, which are synthetic organic compounds widely used. To decompose under certain conditions, this class of dye develops carcinogenic potential, becoming toxic to humans and ecosystems. The adsorption process is one of the methods most commonly used wastewater treatment for such industrial waste. This procedure aims at removing contaminants from wastewater through an adsorbent material. Are predominant factors for the success of adsorption, the proper choice of sorbent, its economic viability and low toxicity. For vegetable biomasses can be used as adsorbent means applying unit operations for the preparation of this material is usually required. Among the techniques used for this purpose, we highlight the grinding and drying. According to the foregoing, the main objective of this study was to analyze the influence of drying and grinding on the adsorption efficiency of the dye Congo Red by Formosa papaya seeds (Carica papaya L.). In the first stage of work, we performed an investigative study of the application of the seeds of papaya fruit for the adsorption of Congo Red dye, which obtained a removal efficiency ranging from 6.5 to 43%. In the second stage, there was the physical characterization (distribution of average particle size, true density, bulk density and porosity of the bed), physico-chemical (sorption isotherms) and morphological inspection of seeds (microscopy). This characterization step seeds were analyzed in whole and fresh, whole and dry milled and physical conformations and dry. In the third step was conducted to study the kinetics of drying seeds in a fixed-bed dryer with air flow parallel, where the variables drying temperature (40 to 60 ° C), air speed were evaluated (1 and 2 m / s), height of the tray (5 and 10 mm) and physical conformation seeds (whole and ground). In the fourth step, the favorable for the adsorption of Congo Red dye were determined conditions, and such conditions occurred in the effluent concentration of 50 mg / L biomass mass ratio by volume of effluent 0.01 g / ml and contact time with the effluent of the biomass of 30 min. In the fifth step, we carried out the study of the influence of drying and grinding on the adsorption efficiency of Congo Red dye from seeds of papaya fruit (Carica papaya L.). In this study the biomass presented the highest adsorption efficiencies, with values of about 58%, dry seeds were ground in physical conformation and conditions of T = 60 ° C and v = 1 m / s. Finally, we determined the maximum adsorption capacity of Congo Red dye, obtaining a value of approximately 15 mg of Congo Red dye adsorbed for each gram of seed used.