Hydrogen (H2) and liquid petroleum gas (LPG) sensing properties of SnO2 thin films obtained by direct oxidation of chemically deposited SnS films has been studied. The SnS film was prepared by a chemical technique called SILAR (Successive Ionic Layer Adsorption and Reaction). The sensor element comprises of a layer of chemically deposited SnO2 film with an overlayer of palladium (Pd) sensitiser. The Pd sensitiser layer was also formed following a chemical technique. The double layer element so formed shows significantly high sensitivity to H2 and LPG. The temperature variation of sensitivity was studied and the maximum sensitivity of 99.7% was observed at around 200°C for 1 vol% H2 in air. The response time to target gas was about 10 seconds and the sensor element was found to recover to its original resistance reasonably fast. The maximum sensitivity of 98% for 1.6 vol% LPG was observed at around 325°C. The sensor response and recovery was reasonably fast (less than one minute) at this temperature.

Looking for alternative sources of energy to generate electricity has been a hot topic for society for a very long time. The need to replace current energy resources such as fuel, oil, and gas is increasing, and the replacement comes from energy obtained from the wind, sun, and sea waves. In many cases, valuable raw materials can be obtained in addition to energy production, while having a significant environmental effect simultaneously.
The shortage of energy and raw material resources in many countries stimulates the growth of interest in all potential sources of energy – solar, wind, wave, tidal – has lead to accelerating the demand for oil and gas, shale gas, as well as the expansion of the areas for the cultivation of technical crops for biofuels. Classical energy resources like oil, gas and coal are serious polluters of the natural environment. Especially harmful is the release of carbon dioxide and sulfur oxides during the exploitation of these resources.
A significant energy raw material potential of non-traditional resources lies in the waters and bottom of the Black Sea, which is a natural geobiotechnological reactor, capable of producing a variety of energy raw resources.
This paper discusses the use of hydrogen sulfide available in the Black Sea waters to produce energy and useful industrial products and proposes the respective. The technology also has an ecological effect in terms of the purification of the hydrogen sulfide pool. The paper also discusses some technologies for the separation of hydrogen sulfide to hydrogen and sulfur. An estimation of the heat value of hydrogen sulfide in the water of the Black Sea is also presented.

A hybrid multi-infeed HVDC (HMIDC) system is composed of line-commutated converter-based high-voltage direct current (LCC-HVDC) and voltage-source converterbased high-voltage direct current (VSC-HVDC), whose receiving ends have electrical coupling. To solve the problem of low-frequency oscillation (LFO) caused by insufficient damping in the HMIDC system, according to the multi-objective mixed H2/H∞ output feedback control theory with regional pole assignment, an additional robust damping controller is designed in this paper, which not only has good robustness, but also has strong adaptability to the change of system operation mode. In the paper, the related oscillation modes and transfer function of the controlled plant are obtained, which are identified by the total least squares estimation of signal parameters via rotary invariance technology (TLS-ESPRIT). In addition, the control-sensitive point (CSP) for suppressing LFO based on the small disturbance test method is determined, which is suitable for determining the installation position of the controller. The results show that the control sensitivity factor of VSC-HVDC is greater than that of LCC-HVDC so that adding an additional damping controller to VSC-HVDC is better than LCC-HVDC in suppressing the LFO of HMIDC. Finally, a hybrid double infeed DC transmission system with three receiving terminals is built on PSCAD/EMTDC where the time-domain simulations are performed to verify the correctness of the CSP selection and the effectiveness of the controller.

Catalytic converters contain the catalytic substance in their structure, which is a mixture of Platinum Group Metals (PGMs). The prices of these metals and a growing demand for them in the market, make it necessary to recycle spent catalytic converters and recovery of PGMs. In the study, the effect of ozone and hydrogen peroxide application on the possibility of extracting PGM from used car catalysts was investigated. The catalytic carrier was milled, sieved and then the fractions with the desired grain size were treated with the appropriate HCl mixture and 3%, 5%, 10%, 15% and 30% H2O2, respectively, and the tests were also carried out at temperature 333 K. Ozone tests were conducted with the O3 flow in the range of 1,3,5 g/h. Samples for analysis were collected after 30 min, 1 h, 2 h, 3 h and after 4 h, respectively. The residue after the experiments and filtration process was also analysed. The obtained results confirmed the assumption that PGMs can be extracted using hydrochloric acid with the addition of H2O2 or ozone as oxidants. It allows to significantly intensify the carried out reactions and to improve the rate of PGMs transfer to the solution.

Many of the drugs used arc not completely metabolized in the human body and with urine and faces arc introduced into the sewage system. Finally, due to their incomplete removal during the conventional wastewater treatment process (CWTP), they can be released into the receiving water. One of the medicaments frequently detected in surface water is diclolcnac. The present study addresses the problem of diclofcnac removal in various aquatic samples using advanced oxidation processes (AOPs). The experiments were performed in distilled water and in biologically treated wastewater. The following AO Ps were applied: Fenlon 's reagent, UVand UV/H2O2-processes. The concentration of diclolcnac in distilled water corresponded to the concentration of this drug in human urine (ca. 20 mg-dm'). The real wastewater samples contained diclofcnac concentrations ranging from 630 to 790 ng-dm-'. The photodcgradation of diclolcnac was carried out in the photorcactor with a medium pressure Hg-vapor lamp (400 W). In the Fcnton's reaction different molar ratiosof H2O2/Fc'' were used. The diclotcnac mineralization (TOC removal) strictly depended on the amount of 1-1,0, applied in the Fcnton's reaction. Diclofcnac was rapidly degraded by direct photolysis (UV) and in UV/H2O2,-process both in distilled water and in wastewater samples. The results proved that the advanced oxidation processes arc cflcctive in diclofcnac removal from aquatic samples. The pseudo first order rate constants It)!' diclolcnac photodcgradation were determined.

A new extraction process suitable for treating refractory CuCo2S4 under atmospheric pressure acidic leaching conditions was investigated. The effect of variables such as oxidant species, liquid-to-solid ratio, leaching time, oxidizing agent and mineral quality ratio, H2SO4 concentration, temperature and sodium chloride concentration on the extraction efficiency of Co, Cu and Fe from CuCo2S4 were investigated. Under optimal conditions including P80-P90 of the sample was d < 0.0074 mm, stirring speed of 400 rpm, leaching time of 8 h with sodium chlorate (NaClO3) and mineral quality ratio of 0.5, 2 mol/L H2SO4, liquid-to-solid ratio of 7, leaching temperature of 90°C and 4 mol/L sodium chloride. The leaching efficiency of Co, Cu, and Fe were nearly 97.08%, 100%, and 92.45%, respectively. Furthermore, the contents of cobalt and copper in leaching residue were all less than 0.4 wt.%, which satisfies the requirements of industrial production.

Surfactants after their use are discharged into aquatic ecosystems. These compounds may be harmful to fauna and flora in surface waters or can be toxic for microorganisms of the activated sludge or biofilm in WWTP. In order to determine effectiveness of different advanced oxidation processes on the degradation of surfactants, in this study the degradation of anionic surfactants in aqueous solution using photolysis by 254 nm irradiation and by advanced oxidation process in a H2O2/UVC system was investigated. Two representatives of anionic surfactants, linear alkyl benzene sulphonate (LAS-R11–14) and ether carboxylic derivate (EC-R12–14E10) were tested. The influence of pH, initial surfactant concentration and dose of hydrogen peroxide on the degradation was also studied. Results show outstanding effectiveness of the H2O2/UVC system in the removal of surfactant from aqueous solutions.