Electrochemical scission of C–S bond in ethanethiol on a modified β-PbO2 anode in aqueous solution

Nanocomposite based on graphene and intercalated covalent organic frameworks with hydrosulphonyl groups for electrochemical determination of heavy metal ions

An electrochemical sensor constructed by intercalated composites was developed for determination of heavy metal ions. The intercalated composites were composed of hydrosulphonyl functional covalent organic frameworks (COF-SH) and graphene (G). The presence of numerous adsorption sites, such as 18 sulfur atoms and 30 nitrogen atoms per big circle of COFs on COF-SH, was beneficial for the accumulation of heavy metals, while the graphene enhanced the electrical conductivity. The obtained sensor under the optimal conditions successfully detected the presence of heavy metal ions in coastal water samples at concentrations ranging from 1 to 1000 μg L^-1. The detection limits of Cd (II), Pb (II), Cu (II), and Hg (II) were 0.3, 0.2, 0.2, and 1.1 μg L^-1, respectively. Furthermore, the sensor still exhibited good stability after multiple uses less than 5%. When it is used in the analysis of actual samples, the recovery of standard addition is higher than 95%. In sum, the combination of hydrosulphonyl functional COFs with graphene looks very promising for the assembly of sensors with high sensitivity toward the determination of heavy metal ions for coastal environmental monitoring.

Technologies for deodorization of malodorous gases

There is an increasing number of citizens' complaints about odor nuisance due to production or service activity. High social awareness imposes pressure on entrepreneurs and service providers forcing them to undertake effective steps aimed at minimization of the effects of their activity, also with respect to emission of malodorous substances. The article presents information about various technologies used for gas deodorization. Known solutions can be included into two groups: technologies offering prevention of emissions, and methodological solutions that enable removal of malodorous substances from the stream of emitted gases. It is obvious that the selection of deodorization technologies is conditioned by many factors, and it should be preceded by an in-depth analysis of possibilities and limitations offered by various solutions. The aim of the article is presentation of the available gas deodorization technologies as to facilitate the potential investors with selection of the method of malodorous gases emission limitation, suitable for particular conditions.

Decomposition of Ethanethiol by a Corona Radical Injection System

The decomposition of ethanethiol by a corona radical injection system, using water vapor and O3as radical source, was investigated. It is found that only 83.6% of ethanethiol can be decomposed in dry air flow with relative humidity of 13.4%. A proper quantity of water vapor injection can improve the decomposition efficiency, but which is not always increased. The maximum decomposition efficiency of 99.1% can be obtained in wet air flow with relative humidity of 74.7%. 97.6% of ethanethiol can be decomposed when the relative humidity of gas flow is 51.6%, but it is found that only 76.3% of element sulfur is converted to SO2, based on sulfur balance. However, the conversion efficiency of sulfur to SO2increases obviously with the increasing of O3injection. The decomposition efficiency of ethanethiol and conversion efficiency of sulfur to SO2can reach 99.8% and 95.3% respectively, when O3is injected into the reactor by high voltage electrode tubes with concentration of 1 g/m3 and flow rate of 300 L/h. The decomposition products are SO2, CO2and H2O, while no organic product is found, based on which the decomposition mechanism is discussed. The weakest chemical bond C-S in ethanethiol molecule is firstly decomposed to ·SH and ·C2H5radicals. ·SH can be oxidized to elemental sulfur and SO2, and ·C2H5is oxidized to CO2and H2O.

Integration of advanced oxidation processes at mild conditions in wet scrubbers for odourous sulphur compounds treatment

The effectiveness of different advanced oxidation processes on the treatment of a multicomponent aqueous solution containing ethyl mercaptan, dimethyl sulphide and dimethyl disulphide (0.5 mg L(-1) of each sulphur compound) was investigated with the objective to assess which one is the most suitable treatment to be coupled in wet scrubbers used in odour treatment facilities. UV/H2O2, Fenton, photo-Fenton and ozone treatments were tested at mild conditions and the oxidation efficiency obtained was compared. The oxidation tests were carried out in magnetically stirred cylindrical quartz reactors using the same molar concentration of oxidants (hydrogen peroxide or ozone). The results show that ozone and photo-Fenton are the most efficient treatments, achieving up to 95% of sulphur compounds oxidation and a mineralisation degree around 70% in 10 min. Furthermore, the total costs of the treatments taking into account the capital and operational costs were also estimated for a comparative purpose. The economic analysis revealed that the Fenton treatment is the most economical option to be integrated in a wet scrubber to remove volatile organic sulphur compounds, as long as there are no space constraints to install the required reactor volume. In the case of reactor volume limitation or retrofitting complexities, the ozone and photo-Fenton treatments should be considered as viable alternatives.