Chemical and toxicological evaluation of pyrotechnically disseminated terephthalic acid smoke

Kinetics Study of Hydrothermal Degradation of PET Waste into Useful Products

Kinetics of hydrothermal degradation of colorless polyethylene terephthalate (PET) waste was studied at two temperatures (300 °C and 350 °C) and reaction times from 1 to 240 min. PET waste was decomposed in subcritical water (SubCW) by hydrolysis to terephthalic acid (TPA) and ethylene glycol (EG) as the main products. This was followed by further degradation of TPA to benzoic acid by decarboxylation and degradation of EG to acetaldehyde by a dehydration reaction. Furthermore, by-products such as isophthalic acid (IPA) and 1,4-dioxane were also detected in the reaction mixture. Taking into account these most represented products, a simplified kinetic model describing the degradation of PET has been developed, considering irreversible consecutive reactions that take place as parallel in reaction mixture. The reaction rate constants (k1–k6) for the individual reactions were calculated and it was observed that all reactions follow first-order kinetics.

Guanidinium 5,5'-Azotetrazolate: A Colorful Chameleon for Halogen-Free Smoke Signals

A progressive halogen‐free multicolored smoke system to obtain white, red, violet, yellow, green, and blue smoke color is presented. The nitrogen‐rich salt guanidinium 5,5′‐azotetrazolate (GZT), which is usually applied as a gas generator or propellant ingredient, was combined with different smoke dyes (Solvent Red 1, Solvent Violet 47, Solvent Green 3, Solvent Yellow 33). These two‐component smoke mixtures offer a convenient and safe multicolor approach without the need for potassium chlorate or any other hazardous material. The common smoke characteristics with respect to burn time/burn rate, yield factor, transfer rate, as well as energetic properties were determined and compared with classic chlorate‐based formulations currently used. To the best of our knowledge, nothing comparable is known in the literature and a completely new research area in modern pyrotechnics is opened.

Terephthalic acid occupational exposure and its effect on organ functions in fiber workers

OBJECTIVES

: To investigate the exposure to terephthalic acid (TPA), and to evaluate it's effects on organ function including the potential risk factors for uroliths and bladder tumor to TPA.

METHODS

: Exposure-response modeling was carried out in a cohort of 141 TPA exposure workers and three subgroups were classified according to their urine TPA concentration. The control group consisted of 77 workers with no exposure to TPA dust. The inhalatory exposure of the application workers was estimated from biological monitoring data. Urine and blood samples were collected from all workers before and after work shift to monitor variables of liver, kidney, and lung. Haematological variables and serum biochemistry were valued, pulmonary functions were tested, and ion changes in both serum and urine were measured.

RESULTS

: Increased urinary excretion of TPA (0-5mmol/molCr after the shift) reflected occupational workers TPA exposure. We also observed the exposure-response relations for the intensity of TPA exposure and the urine variables. Increased serum aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) but within normal range is not increased. The slightly increased serum angiotensin-converting enzyme activity (SACE) was considered to be related to particulate of airborne TPA dust inhalation. No difference between referents and workers exposed to TPA was found for haematological variables.

CONCLUSIONS

: No clinical organ dysfunctions were found in this investigation working with TPA. However, special precautions are still necessarily taken to avoid excessive or prolonged contact.