Rational design of a novel MOF-based ternary nanocomposite for effectively monitoring harmful organophosphates in foods and the environment.

Methyl parathion (MP) is a widely used organophosphate insecticide that is extremely toxic due to its ability to irreversibly inhibit acetylcholinesterase in the body and persistently accumulate in the environment. Timely detection of MP can prevent harmful residue exposure to humans. Therefore, the development of fast, efficient electrochemical methods to detect trace MP has been highly beneficial for monitoring harmful residues in foods and environment to ensure food safety and ecological conservation. Herein, a novel hybrid metal-organic framework (MOF) nanocomposite composed of Pt nanoparticles (PtNPs), multi-walled carbon nanotubes (MWCNTs), and UiO-66-NH2 (PtNPs/UiO-66-NH2/MWCNTs) was rationally designed and prepared by a facile two-step strategy for the sensitive determination of MP. The synergistic effects are illustrated in detail using XRD, XPS, FTIR, TEM, and SEM studies as well as electrochemical technologies such as CV, EIS, and DPV. In addition, the performance of the ternary nanocomposite for detecting MP was investigated by comparing it with the binary-component one. The results showed that the PtNPs/UiO-66-NH2/MWCNT-based electrochemical sensor exhibited outstanding sensitivity of 21.9 µA µM-1 cm-2, satisfactory low detection limit of 0.026 µM and wide linear range of 0.11-227.95 µM for MP analysis. Furthermore, the fabricated sensor delivered distinguished freedom from interferences, outstanding regeneration ability, and adequate recoveries for fresh foods and river water samples. In conclusion, the proposed PtNPs/UiO-66-NH2/MWCNT-based sensor provides a potentially useful analytical tool for determining hazardous residues of OPs in foods and the environment.

[Composite CVOCs Removal in a Combined System of Nonthermal Plasma and a Biotrickling Filter].

A coupling system of nonthermal plasma and a biotrickling filter was used to remove a gas mixture of chlorobenzene (CB) and dichloromethane (DCE). The effects of inlet gas concentration and gas flow rate on the removal of the target pollutants in the coupling system were investigated at the frequency of 10000 Hz and specific input energy (SIE) of 6111 J·L-1. Furthermore, the advantages of the plasma-bio-coupled system were revealed by analyzing the relationship between the degradation products and SIE, biomass, or biodiversity in the biotrickling filter. The results showed that when the SIE and gas flow rate were constant, increasing the initial concentration would decrease the removal efficiency of the mixed gas. The optimal appropriate gas flow rate was 0.71 L·min-1 when considering the cost. The CO2 production amount, CO2 selectivity, and chloride ion concentration increased with the increase of SIE when both the CB and DCE concentrations were 500 mg·m-3 and the gas flow rate was 0.71 L·min-1. The protein content of the biofilter column gradually increased as the reactor operation progressed, and the biomass of the lower layer was higher than that of the upper layer. The high-throughput sequencing analysis showed that the biological community in the biotrickling filter keeped rich and diversified.

[Degradation Characteristics of Composite CVOCs by Non-thermal Plasma].

Non-thermal plasma was used as a pretreatment technology for bio-trickling filter, employing chlorobenzene and dichloroethane as target pollutants. This experiment was conducted to study the purification effect and degradation product in NTP under different frequency power supply,to provide a theoretical basis for coupling with biotechnology. The results showed that the removal efficiency for mixed waste gas in the plasma first increased and then decreased with the increase of the SIE. The maximum energy efficiency was obtained at 6111 J·L-1 under high frequency power and 7167 J·L-1 under low frequency condition, respectively. Extending residence time caused a rise in mixed gas removal efficiency, but the removal load didn't always increase and the highest removal load was observed with the residence time of 5 s, so 5 s was regarded as the optimal reaction condition for the subsequent analysis in this study. The degradation products were analyzed under the specific conditions. Experimental results showed that the amount and the selectivity of carbon dioxide both increased with the increase of SIE in the plasma reactor. The amount of ozone increased to a maximum value and then decreased with the increase of SIE in the plasma reactor, and the amount of ozone produced in low-frequency power plasma was lower than that in high-frequency power. The trend of TOC values was similar to the trend of ozone generation, indicating that the best water solubility was obtained at the highest energy efficiency.