Thermal behavior of food preservative sorbic acid and its derivates.

Sorbic acid and its potassium and calcium salts used as food preservatives and sorbic chloride were submitted to thermal analysis in order to characterize their thermal behavior on heating and cooling processes, using TG/DTG/DTA, TG-MS, DSC, hot stage microscopy and DRX analysis. Sorbic acid melted and decomposed under dynamic heating. Under isothermal it sublimated without decomposition before melting (T < 134 °C). The potassium salt presented a solid-solid phase transition before decomposition. Both potassium and calcium salts decomposed in temperatures higher than the acid without melting, producing the respective carbonates and oxides as final residues. Sorbic chloride evaporate without condensation, on dynamic heating.

Thermal behavior of inosine 5'-monophosphate in acidic form and as alkali and alkaline earth salts.

Inosine 5'-monophosphate in acidic form and its lithium, potassium, magnesium, calcium, strontium and barium were prepared from the sodium salt, characterized by elemental analysis and Fourier transform infrared spectroscopy and submitted to thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and thermogravimetry coupled to infrared spectroscopy (TG-FTIR) of the volatile products evolved during heating. All the salts were hydrated containing from 4 to 7.5 H2O. After dehydration these salts decomposed releasing the nitrogenous base followed by the ribose group, and producing pyrophosphates as final residue. Evolved Gas Analysis (EGA) reveled the release of water, isocyanic acid and hydrocyanic acid during decomposition of the organic moiety. It was observed only water loss up to 200 °C. At temperatures above 200 °C, the nucleotides were unstable and decomposed, implying that foods containing those additives should be processed below this temperature. Finally, a general mechanism for the decomposition of the inosinates was proposed.

Evaluation of waste biomasses and their biochars for removal of polycyclic aromatic hydrocarbons.

This work evaluates the use of biomasses and their biochars as adsorbents to remove polycyclic aromatic hydrocarbons from water. Coconut waste (CW) and orange waste (OW) were pyrolyzed at 350 °C to produce the corresponding biochars (BCW and BOW). Adsorption tests using a mixed solution of benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, and dibenzo(a,h)anthracene showed removal percentages of 30.33-83.43% (CW), 47.09-83.02% (BCW), 24.20-74.25% (OW), and 23.84-84.02% (BOW). The adsorption mechanisms appeared to involve π-π interactions of similar groups of the adsorbate and adsorbent, together with hydrophobic effects. There was no indication of competition between the PAHs for the adsorption sites, and there was evidence of cooperative adsorption. The PAHs could be desorbed from the adsorbents with efficiencies in the range 34.88-72.32%, and the reuse of the adsorbents in two further cycles demonstrated their potential for use in the removal of PAHs from water.