The consumption and production of biodiesel has grown dramatically in recent decades, motivated by a strong interest in renewable energy. This has generated a surplus of its main by‐product, glycerol. Several catalytic processes have been proposed to generate alternatives for using this excess glycerol, mainly focusing on its transformation into high value‐added chemical products. Various products, ranging from syngas to organic acids, such as acrylic or lactic acid, along with 1,2‐propanediol, 1,3‐propanediol, glycerol ethers or even polymers, have been produced starting from glycerol. Among this multitude of possibilities, the production of lactic acid is one of the most interesting alternatives to valorize glycerol, because of the wide range of applications described for this organic acid. This review focuses on recent studies dealing with the catalytic conversion of glycerol to lactic acid, using different heterogeneous catalysts, and evaluates the factors influencing the oxidation catalytic process and the proposed reaction mechanisms. Finally, recent studies on the separation and purification of lactic acid using ion exchange chromatography resins are also reported. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd

Production of lactic acid by hydrothermal conversion of glycerol is an option to add value to the large amounts of glycerol that is being generated during the production of biodiesel. This work aimed to separate lactic acid by ion-exchange resins in a fixed-bed column. Adsorption isotherms were obtained from the breakthrough curves using different initial concentrations of lactic acid (60-302 g/l) and temperatures (30, 40 and 60 °C). Maximum adsorption capacities were estimated by the Langmuir model. Adsorption and desorption cycles for a binary and a real mixture were performed. The methodology proposed for the separation of lactic acid in a fixed-bed column presented high values of adsorptive capacity for both Amberlite IRA-96 and Amberlite IRA-67 resins at 30 °C. Lactic acid was more strongly adsorbed by Amberlite IRA-96 than the IRA-67 resin with maximum adsorption capacity of 544 and 341 g/l, respectively. Chromatographic experiments for the singlecomponent solution (lactic acid), binary mixture (lactic acid and glycerol) and real mixture showed high values of recovery (29.2%, 31.3% and 23.5%, respectively) and productivity (3.14, 7.00 and 2.43 kg of lactic acid/kg resin. day).

This study evaluates the influence of the presence of oxygenated groups created onto the surface of activated carbon (AC) on its ability to disperse platinum (Pt) or palladium (Pd) particles and on its catalytic performance to drive the transformation of glycerol into lactic acid. AC pretreatment consisted of oxidation in the presence of HNO3 aqueous solutions conducted at 50, 70, and 90 °C, aiming at creating oxygenated groups on the support surface. The catalytic activities of Pt/AC and Pd/AC catalysts were evaluated in the production of lactic acid from both glycerol and crude glycerin. Lower-temperature pretreatments provided catalytic supports showing higher metal uptakes together with similar catalytic activity conversion and yield for both metals (5% Pt/AC and 10% Pd/AC). The catalysts were stable in five reaction cycles, and only negligible activity loss was detected.

The study objective was to measure the effect of consumption of a beverage mixed with a high-iron sweetener (evaporated sugarcane juice known as rapadura) on hemoglobin levels in preschool children, and to compare it with the effect of consuming the same beverage sweetened with refined sugar. Research consisted of a 12-week randomized, controlled double-blind trial conducted in 2007 at a state-run school in Sobral, Brazil, among children aged 2-3 years. The study sample was divided into two groups-one consuming cashew juice mixed with 25 g of rapadura and 40 mg of ascorbic acid (per 200-mL serving), and another consuming the same quantity of juice and ascorbic acid sweetened with 25 g of standard refined sugar. A significant statistical increase in hemoglobin was observed in the group consuming the rapadura-fortified beverage. It was therefore concluded that consumption of rapadura increased hemoglobin and thus reduced iron deficiency anemia in preschool children.

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The transition from fossil to bio-based fuels is a requisite for reducing CO2 emissions in the aviation sector. Jet biofuels are alternative aviation fuels with similar chemical composition and performance of fossil jet fuels. In this context, the Hydroprocessing of Esters and Fatty Acids (HEFA) presents the most consolidated pathway for producing jet biofuels. The process for converting esters and/or fatty acids into hydrocarbons may involve hydrodeoxygenation, hydrocracking and hydroisomerization, depending on the chemical composition of the selected feedstock and the desired fuel properties. Furthermore, the HEFA process is usually performed under high H2 pressures and temperatures, with reactions mediated by a heterogeneous catalyst. In this framework, supported noble metals have been preferably employed in the HEFA process; however, some efforts were reported to utilize non-noble metals, achieving a similar performance of noble metals. Besides the metallic site, the acidic site of the catalyst is crucial for product selectivity. Bifunctional catalysts have been employed for the complete process of jet biofuel production with standardized properties, with a special remark for using zeolites as support. The proper design of heterogeneous catalysts may also reduce the consumption of hydrogen. Finally, the potential of enzymes as catalysts for intermediate products of the HEFA pathway is highlighted.

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