Odivan Zanella

Pressurized liquid extraction and chemical characterization of safflower oil: A comparison between methods.

This work investigates the extraction process of safflower oil using pressurized ethanol, and compares the chemical composition obtained (in terms of fatty acids) with other extraction techniques. Soxhlet and Ultrasound showed maximum global yield of 36.53% and 30.41%, respectively (70°C and 240min). PLE presented maximum global yields of 25.62% (3mLmin(-1)), 19.94% (2mLmin(-1)) and 12.37% (1mLmin(-1)) at 40°C, 100bar and 60min. Palmitic acid showed the lower concentration in all experimental conditions (from 5.70% to 7.17%); Stearic and Linoleic acid presented intermediate concentrations (from 2.93% to 25.09% and 14.09% to 19.06%, respectively); Oleic acid showed higher composition (from 55.12% to 83.26%). Differences between percentages of fatty acids, depending on method were observed. Results may be applied to maximize global yields and select fatty acids, reducing the energetic costs and process time.

Electrochemical regeneration of phenol-saturated activated carbon – proposal of a reactor

ABSTRACT An electrochemical process was used to investigate the activated carbon regeneration efficiency (RE) saturated with aromatics. For this purpose, an electrochemical reactor was developed and the operational conditions of this equipment were investigated, which is applied in activated carbon regeneration process. The influence of regeneration parameters such as processing time, the current used, the polarity and the processing fluid (electrolyte) were studied. The performance of electrochemical regeneration was evaluated by adsorption tests, using phenol as adsorbate. The increase in current applied and the process time was found to enhance the RE. Another aspect that indicated a better reactor performance was the type of electrolyte used, showing best results for NaCl. The polarity showed the highest influence on the process, when the cathodic regeneration was more efficient. The electrochemical regeneration process developed in this study presented regeneration capacities greater than 100% when the best process conditions were used, showing that this form of regeneration for activated carbon saturated with aromatics is very promising. GRAPHICAL ABSTRACT

Study of CaCl2 as an agent that modifies the surface of activated carbon used in sorption/treatment cycles for nitrate removal

The efficiency of the application of a chemically-modified activated carbon surface was investigated. The purpose of this study was to examine the effect of treatment with CaCl2 solution at a concentration of 2000 mg.L-1 on the sorption of nitrate ions from aqueous solutions in successive sorption/t reatment cycles. The sorbent was initially subjected to chemical treatment with CaCl2 and subsequently to the sorption process. Nine sorption cycles were performed. The concentrations of nitrate ions in the solution were measured by UV-Vis spectrophotometry before and after sorption. The results show that treatment with CaCl2 caused a significant increase in the percentage removal for each treatment step, reaching a removal rate of 80% of nitrate in the solution after nine cycles.

Successive cycles of sorption/regeneration for granular activated carbon in the removal of nitrate ions

AbstractGranular activated carbon was used in the sorption of nitrate ions with subsequent regeneration by assessing the capacity of the sorbent in successive cycles of sorption/regeneration (S/R). Solutions of HCl, C6H8O7, NaOH, CaCl2, as well as H2O were employed in the regeneration of activated carbon saturated with nitrate. Solution of CaCl2 was the best regenerative agent. Contact times of 30 min and 400 mL of 2,000 mg L−1 CaCl2 solution were used for regeneration. Twenty cycles of S/R, which yielded 54% nitrate removal at the end of the cycles, were possible. During regeneration, the concentration of Ca2+ in the solution of CaCl2 was monitored to keep the initial concentration constant. After 20 S/R cycles, the sorbent was desorbed using 50 mL of 100 mg L−1 HCl and 50 mL H2O (60°C). Over 20 S/R cycles were performed for the sorbent recovered with HCl and 20 S/R cycles for the sorbent desorbed with H2O (60°C). Approximately 58% of nitrate removal was achieved at the end of 20 S/R cycles in both cases...

Equilibrium studies, kinetics and thermodynamics of anion removal by adsorption

In this work, granular activated carbon (GAC) functionalised with CaCl2 was used to remove nitrate and sulphate from aqueous solutions. Functionalisation with CaCl2 influenced the physico-chemical properties and improved the adsorption capacity of activated carbon. The effect of pH on adsorption was investigated, and no significant difference was observed. The adsorption process was found to be of an exothermic nature. Thermodynamic parameters were calculated including the change in Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°). The pseudo-first-order model, pseudo-second-order model and Elovich equation were used to study the adsorption kinetics. The intraparticle diffusion model, Boyds model and Banghams equation were investigated to determine the mechanism of this process. The data showed that nitrate adsorption on activated carbon follows second-order kinetics, whereas that of sulphate follows first-order kinetics. The control mechanism for the two components was determined to be particle diffusion.