Rapid analysis of carboxylic acids and esters with a direct analysis in real time ion source.

RATIONALE: Coal oxidation produces carboxylic acids (CAs), including aliphatic acids, benzoic acids, and benzenepolycarboxylic acids, which are important fine chemicals which could be used to understand the structural features of coals. However, detecting CAs usually presents great challenges due to extremely troublesome pretreatments. Therefore, it is essential to develop an analytical method for the rapid detection of CAs from coal oxidation. METHODS: A series of model compounds (MCs) of oxidation products and two practical samples were investigated by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) under three different analytical conditions (ionizing gas temperature, organic solvent, and MC concentration). RESULTS: Ionizing methyl benzoate, dimethyl phthalate, and dimethyl adipate produces typical ions of methyl esters, including [M - OCH3 ]+ , [M + H]+ , and [M + NH4 ]+ . In contrast, the characteristic ions generated from CAs are polymer ions, such as [2 M + NH4 ]+ , [3 M + NH4 ]+ , [4 M + NH4 ]+ , and [5 M + NH4 ]+ , indicating the strong intermolecular hydrogen-bond interaction among CAs. CONCLUSIONS: Results suggest that DART-TOFMS could rapidly analyze CAs or esters in coal oxidation products according to their typical ions to further gain deep insights into the coal structure.

Detoxification modification of coal-tar pitch by ultraviolet & microwave radiation-enhanced chemical reaction and toxicity evaluation by chemical index and cytotoxicity assay in vitro.

Although coal tar pitch (CTP) has a large yield in China, its large-scale and effective utilization is significantly hindered because of existing and possibly releasing polycyclic aromatic hydrocarbons (PAHs). Therefore, it is an imminent problem how to prepare an environmentally friendly CTP by detoxification modification. In the investigation, a typical CTP was subjected to structural characterization via solid-state 13C NMR and gas chromatograph/mass spectrometer, which confirmed the existence of dominant PAHs such as fluoranthene, pyrene, as well as benzo[a]pyrene, and few heterocyclic compounds. Subsequently, the CTP was modified using 10-undecenal via alkylation reaction enhanced by ultraviolet & microwave radiation. Compared with the original CTP, the total content of 16 toxic PAHs in the modified CTP decreased with a reduction efficiency of above 90%. According to different environmental standards, toxic equivalent quotient of CTP after modification was reduced by above 90%. In order to veritably and fully evaluate the toxicity of CTP, a living vascular smooth muscle cell (A-10 cell) in vitro was used in the cell counting kit-8 assay. The viability of A-10 cell was always higher when exposed to modified CTP than the original CTP. These results powerfully indicated that the enhanced modification was actually effective and efficient for reducing the toxicity of CTP.

Removal of phenol by powdered activated carbon prepared from coal gasification tar residue.

Coal gasification tar residue (CGTR) is a kind of environmentally hazardous byproduct generated in fixed-bed coal gasification process. The CGTR extracted by ethyl acetate was used to prepare powdered activated carbon (PAC), which is applied later for adsorption of phenol. The results showed that the PAC prepared under optimum conditions had enormous mesoporous structure, and the iodine number reached 2030.11 mg/g, with a specific surface area of 1981 m2/g and a total pore volume of 0.92 ml/g. Especially, without loading other substances, the PAC, having a strong magnetism, can be easily separated after it adsorbs phenol. The adsorption of phenol by PAC was studied as functions of contact time, temperature, PAC dosage, solution concentration and pH. The results showed a fast adsorption speed and a high adsorption capacity of PAC. The adsorption process was exothermic and conformed to the Freundlich models. The adsorption kinetics fitted better to the pseudo-second-order model. These results show that CGTR can be used as a potential adsorbent of phenols in wastewater.

The application of the reverse engineering and rapid prototyping technology in the design of respiratory masks / 中国医疗器械杂志

The application of the reverse engineering and rapid prototyping technologies in the design of respiratory masks is introduced in this paper. Practice indicates that the technologies can reduce the cost and save the time in product developments.