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This work proposes the use of agro-industrial wastes, specifically peanut hull (HP) and orange peel (OP), as adsorbents for dyes, such as Remazol Golden Yellow RNL-150% (RYG), Gray Reactive BF-2R (RG) and Reactive Turquoise Q-G125 (RT). Characterization by Brunauer-Emmett-Teller indicates that the adsorbents are mesoporous, with pHzpc values of 5.0 for HP and 4.0 for OP. Fourier transform-infrared spectroscopy identified carbonyl and sulphonic groups. The initial pH of the best-adsorbing solution of the three colours was 2.0. Increasing the concentration of the adsorbent promoted an increase in the percentage of removal until saturation of the adsorbent. In a factorial design, the largest value of q was obtained with 0.25 g of the adsorbent, with a particle size of < 0.4 mm and a stirring speed of 300 rpm. Such conditions were used in kinetic studies and studies of adsorption equilibrium. The evolution kinetics were rapid in the first few minutes, and after 180 min the system reached equilibrium. The kinetic model that best fit the experimental data to a 95% confidence level for the F test was the pseudo-second-order model for RYG/HP, RG/OP and RT/OP. There was no significant difference between the kinetic models as evaluated by the F test for RYG/OP, RG/HP and RT/HP. The experimental results indicated favourable dye adsorption characteristics for the adsorbents studied. The results of the F test showed that for RYG and RG, there was no significant difference between the two evaluated models. This study suggests that HP and OP are viable alternatives for the treatment of effluents containing RYG, RG and RT dyes.

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Research background. Drying represents a viable unit operation for the preservation of food. Convective drying is the most used method for plant materials. However, it can result in negative changes in food nutrient composition, and other quality parameters, besides having high energy consumption. Pretreatments can represent an alternative to minimize these negative aspects of dried materials. This work aimed to evaluate the use of ethanol and ultrasound before pineapple convective drying and its effect on the product´s color, water activity, ascorbic acid, and total carotenoid contents. Experimental approach. For the pretreatment step, fruit samples were immersed in different ethanol concentration solutions, and experiments were carried out for 10 min with and without using ultrasound (25 kHz). Fruit samples were dried at 60 ºC. A control group (without the pretreatment step) was also dried in the same condition. Semi-theoretical models were used for drying data fitting, and the diffusional model was used to describe the moisture transfer and calculate the effective diffusivities. Water activity, ascorbic acid, total carotenoids, and color analyses were performed. Results and conclusions. The association between ethanol and ultrasound as a pretreatment reduced the drying time of pineapple. Higher effective moisture diffusivities were obtained when ethanol and ultrasound were performed before drying. The Two Term Exponential model presented the best fit for drying experimental data. In comparison to the fresh sample, the dried samples showed a darker color. The pretreatment with ethanol resulted in increased retention of the studied bioactive components. This study represents an improvement for the drying process, providing satisfactory results. Novelty and scientific contribution. Ultrasound and ethanol as a pretreatment to convective drying are promising. However, each food matrix has a typical structure and composition. Therefore, the application of the pretreatment in other products or using other conditions is still necessary to deeply understand and explain their effect on the process and the quality of dried products.

a b s t r a c tEffluent treatment for food industry wastewater is a subject of growing concern among the scientific community. Synthetic dyes are a major case and their presence can disturb aquatic environments and introduce highly toxic potentials to the ecosystem, even at low concentrations. In this study, the chemical kinetics of a degradation process was studied for the treatment of a Tartrazine (E102) and Brilliant Blue (E133) solution by different methods. First, the efficiency of eight advanced oxidative processes systems was investigated in their treatment. The most efficient result was obtained in a UV-solar/H 2 O 2 /TiO 2 system, which reached a degradation percentage of 99.36% in 180 min. Second, a 2 3 factorial planning was used to enhance quantitative degradation in this system and a similar result (99.21%) was reached in 90 min with the optimal conditions. The kinetics of this experiment was fitted in a pseudo-first-order model and the rate constant (k) estimated as 0.0541 min -1 . An artificial neural network was developed for the experiment to describe the degradation behaviour over time with a minimum error. Chemical oxygen demand and conductivity were estimated in order to assure the environmental quality of the samples. A Lactuca sativa bioassay revealed an upturn in LC 50 , the concentration to inhibit 50% of the organism growth, from 39.31% (v/v) to 87.73% (v/v). The result indicates a highly favourable reduction in acute phytotoxicity, that coupled with quantitative efficiency, makes the proposed use of solar light as radiation source and improvements in water quality parameters a suitable tool for large-scale synthetic dye treatment.