Development of laser induced breakdown spectroscopy technique to study irrigation water quality impact on nutrients and toxic elements distribution in cultivated soil

Real-time in situ detection of petroleum hydrocarbon pollution in soils via a novel optical methodology

Petroleum hydrocarbon (PHC) contamination in soils is considered one of the most serious problems currently, of which the detection and identification is a fairly significant but challenging work. Conventional methods to do such work usually need complex sample pretreatment, consume much time and fail to do the in-situ detection. This paper set out to create a novel systematic methodology to realize the goals accurately and efficiently. Based on laser-induced breakdown spectroscopy (LIBS) and self-improved machine learning methods, the innovative methodology only uses extremely simple devices to do the real-time in situ detection and identification work and even realize the quantitative analysis of pollution level accurately. In the study, clean soils mixed with petroleum were served as polluted samples, clean soils to be the blank group for comparison. Based on the elemental information from the spectra obtained by LIBS, machine learning methods were improved and helped optimized the algorithm to identify the PHC polluted soil samples for the first time. Furthermore, a novel model was designed to perform the quantitative analysis of the concentration of PHC pollution in soils, which can be applied to detect the degree of PHC contamination in soils accurately. Finally, the harmful volatile component of the PHC polluted soils was also successfully and identified despite its extremely minimal content in the air. The newly-designed methodology is novel and efficient, which has extensive application prospect in the real-time in situ detection of petroleum hydrocarbon pollution.

Application of a novel hydroxyl functionalized fluorescent covalent organic framework for turn-off ultrasensitive Zn2+ ion detection

In this research, a novel hydroxyl functionalized covalent organic framework (COF) with fluorescence properties was rationally designed based on the reaction between 2,5-dihydroxy-terephthalic-dihydrazide (DHTPz) and 1,3,5-benzenetricarboxaldehyde (Bt) for Zn²⁺ detection. The prepared DHTPz-Bt exhibited strong fluorescence, while the apparent quenching of fluorescence was observed after the introduction of Zn²⁺. Meanwhile, DHTPz-Bt exhibited high sensitivity and promising selectivity during the detection of Zn²⁺. Additionally, the recognition process was revealed to be attributed to the coordination between the hydroxyl groups on the phenyls of DHTPz-Bt and Zn²⁺ ions, as verified by using Fourier-transform infrared spectra and X-ray photoelectron spectra. This work demonstrates the great potential of fluorescent probes by rationally introducing metal ligands, which will lead to a suite of new COF materials for metal ion sensing in a practical manner.