Cross determination of the vapor liquid equilibrium of formaldehyde aqueous solutions by quadrupole mass spectrometry and infrared diode laser spectroscopy

An Upgrade of Apparatus and Measurement Systems for Generation of Gaseous Formaldehyde: A Review

Formaldehyde (FA) is ubiquitous in the atmospheric environment. It is generally the dominant atmospheric carbonyl compound. Due to its well-known carcinogenicity, FA is a compound that arises the attention in the scientific community. In studies concerning the toxicological effects of FA on humans, animals, and the environment, testing and calibration of air sampling systems and analytical instruments are pivotal. Therefore, the preparation of controllable standard gaseous atmospheres containing FA at levels known with precision and accuracy is essential. This review summarizes the procedures for generating the FA atmosphere, given that operative solutions have been evolving recently. Furthermore, an overview on the available system to collect and store gaseous standard is reported. The progressively implemented FA generation techniques, together with commercially-available instruments, are herein described, classified, and compared.

Heterotopic formaldehyde biodegradation through UV/H2 O2 system with biosynthetic H2 O2

Biodegradation was regarded an environmentally benign and cost-effective technology for formaldehyde (CH₂ O) removal. However, the biotoxicity of CH₂ O inhibited microbial activity and decreased removal performance. We developed a novel heterotopic CH₂ O biodegradation process that combined bioelectrochemical system (BES) and UV/H₂ O₂ . Instead of exogenous addition, H₂ O₂ was biosynthesized with electron transferred from electrochemically active bacteria. Heterotopic biodegradation of CH₂ O was more efficient and faster than in situ biodegradation, as confirmed by 69%-308% higher removal efficiency and 98% shorter degradation time. Operated under optimal conditions for 30 min, which are optical distance of 2 cm, initial H₂ O₂ concentration of 102 mg/L, and pH 3, heterotopic biodegradation removed 78%, 73%, 49%, and 30% of CH₂ O with 6, 8, 10, and 20 mg/L initial concentration. Mild formation of hydroxyl radicals from UV/H₂ O₂ is beneficial to sustainable CH₂ O degradation and efficient H₂ O₂ utilization. Heterotopic biodegradation is a promising technology for efficient degradation of other organic compounds with biological toxicity. PRACTITIONER POINTS: H₂ O₂ biosynthesis through electrochemically active bacteria (EAB) served as source of ·OH for CH₂ O removal in UV/H₂ O₂ . Heterotopic CH₂ O biodegradation avoided the biotoxicity of CH₂ O. Heterotopic biodegradation of CH₂ O saved 98% time than in-situ biodegradation. Heterotopic CH₂ O biodegradation improved 69%-308% efficiency than in-situ.

Identification of Di(oxymethylene)glycol in the Raman Spectrum of Formaldehyde Aqueous Solutions by ab Initio Molecular Dynamics Simulations and Quantum Chemistry Calculations

Di(oxymethylene)glycol forms in formaldehyde aqueous solutions by polymerization of methanediol. The structure and hydrogen bond interactions of di(oxymethylene)glycol with water were characterized by performing Car-Parrinello molecular dynamics simulations. The anharmonic vibrational frequencies of di(oxymethylene)glycol in solution were determined with ab initio calculations considering explicitly the hydrogen-bonded water molecules, while other interactions with solvent were described within a polarizable continuum model approach. The calculations allow for a detailed interpretation of the experimental Raman spectrum of formaldehyde aqueous solutions, leading to the assignment of the band at 920 cm(-1) to the symmetric CO stretching mode of di(oxymethylene)glycol.