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The purpose of this research is to investigate the feasibility of utilizing the slag collected after gasification of organic fuel combined with sewage sludge. The residue left after gasification process is likely usable as raw material for production of supercondensers. The sewage sludge neutralization system consists of a dosing system (fuel tank), gasifier, plasma reactor, electrostatic filter, and heat exchangers. For the gasification process, dried solid sewage is supplied in proportion of 70% to biomass 30% by weight. The slag is collected in a specially designed chamber beneath the gasifier. A scanning electron microscope (SEM) was used to evaluate surface morphology of the samples. Elemental analysis of the sewage sludge slag was performed using the energy-dispersive spectroscopy (EDS) method, which showed different solid-state elements contained in the porous structure of the solid phase: carbon 29%, aluminum 26%, potassium 20%, chlorine 1%, and others. The specific surface area of the sewage sludge slag is 6.15 m 2 /g as the BET analysis shows. In order to use the slag as a secondary raw material, detailed analysis of the structure and properties is necessary for a decision on whether the slag left after gasification of sewage sludge is suitable for any further usages. Initial results indicate that the slag may be used for production of electrodes for supercapacitors.Implications: Every year thousands of tons of sewage sludge are formed in Lithuania. Sewage sludge consists of organic and inorganic compounds. Partial combustion, plasma decomposition, and other methods are used to neutralize the sewage sludge. The incineration of sewage sludge results in generation of solid-phase slag. In this paper the material structure and composition of a solid slag (formed during neutralization of sewage sludge) is considered. Also, the impact the ambient temperature on structure and composition of solid slag is analyzed.

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The plasma-activated reactive evaporation technique was used for the formation of indium-tin-oxide (ITO) films. The ITO films were deposited on a heated (up to 350 °C) glass substrates using various mass ratios of indium and tin. The optical and electrical properties of the deposited ITO films were determined. The influence of the indium-to-tin mass ratio on the optical transmittance, bandgap, resistivity and resistance of ITO films was investigated. The bandgap of ITO films was increased from 3.18 to 3.37 eV, and the MIn/MSn ratio increased from 4.25 to 10.00. The average values of optical transmittance at the visible light wavelengths increased from ~43% to ~64% as tin mass was reduced. We demonstrated that ITO films with low resistivity ranging from 7.4 × 10−3 to 43.7 × 10−3 Ω·cm were obtained, and the MIn/MSn ratio changed from 4.25 to 10.00. The ITO film formed at the 9.25 MIn/MSn ratio demonstrated high transparency, a wide bandgap and optimal resistivity and resistance values. The heating characteristics indicated that the frozen ice on the ITO films was completely removed after 30 s when the applied voltage was 24 V.

The influence of alumina additive from 1 to 5 wt. % upon the microstructure and ionic conductivity of ZrO2-8 mol % Y2O3 (YSZ) ceramics, deposited by means of plasma spray technology, was investigated. Plasma sprayed films have been analysed using scanning electron microscopy (SEM) and X-ray analysis (XRD). The microstructural examination reveals that alumina addition decreases the porosity and microcracks of plasma sprayed YSZ. Analysis of SEM micrographs shows that the amount of 5 wt. % alumina substantially improves the microstructure of plasma sprayed zirconia. The crystal structure of all plasma sprayed samples consists of cubic zirconia and α-alumina. By the data of ionic conductivity measurements, no significant influence of annealing at 1073 K for 10 h was noticed on characteristic temperature dependences of σ for plasma sprayed YSZ. Alumina doping from 2 to 5 wt. % considerably increases the ionic conductivity of plasma sprayed zirconia. The higher values of ionic conductivity were obtained when 5 wt. % of Al2O3 powder was added to YSZ.

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