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Determination of resistance to cavitation of pyrophyllite samples
No full textU radu je ispitivana otpornost pod dejstvom kavitacije uzoraka sinterovanog pirofilita. Polazni uzorak pirofilita iz ležišta Parsović-BiH mleven je u vibracionom mlinu na granulaciju 20mm, presovan je i sinterovan na temperaturama (ºC): 1000; 1100; 1200. Za procenu kavitacione otpornosti praćena je promena mase uzorka u funkciji vremena delovanja kavitacije. Primenjena je ultrazvučna vibraciona metoda sa stacionarnim uzorkom prema standardu ASTM G32. Izračunate su kavitacione brzine za sve uzorke, kao osnovni pokazatelj otpornosti materijala pod dejstvom kavitacije. Promena morfologije površine uzorka sa vremenom ispitivanja praćena je primenom skenirajuće elektronske mikroskopije. Na osnovu vrednosti kavitacione brzine i analize morfologije oštećenja površine određena je kavitaciona otpornost ispitivanih uzoraka na bazi pirofilita. Dobijeni rezultati ukazuju da uzorci sinterovanog pirofilita imaju zadovoljavajuću otpornost na dejstvo kavitacije i mogu se primeniti u uslovima manjih kavitacionih opterećenja.The resistance under the action of cavitation of sintered pyrophillite samples was investigated. The initial sample of pyrophillite from the Parsovic-BiH deposit was ground a vibrating mill to a granulation of 20 mm, pressed and sintered at temperatures (⁰C): 100; 1100; 1200. To assess cavitation resistance, the change in sample mass as a function of cavitation time was monitored. The cavitation erosion test was performed using the ultrasonic vibratory cavitation test method according to the ASTM G-32 standard. Cavitation velocites were calculated for all samples, as a basic indicator of the resistance of the material under the action of cavitation. The change in the morphology of the surface with the test time was followed by scanning electron microscopy. Based on the values of cavitation velocity and analysis of the surface damage morphology, the cavitation resistance of the tested samples based on pyrophillite was determined. The obtained results indicate that the samples of sintered pyrophillite have satisfactory resistance to the action of cavitation and be applied in conditions of lower cavitation loads
Hydrothermal carbonization of spent mushroom substrate: Physicochemical characterization, combustion behavior, kinetic and thermodynamic study
No full textHydrothermal carbonization (HTC) was employed for the conversion of the spent mushroom substrate (SMS) into a carbonaceous hydrochar. The effect of operating temperature (180, 200, 220, 240, and 260 ?C) on the physicochemical, structural, and combustion properties of the obtained hydrochars was analyzed. The HTC treatment caused the increase of the higher heating value (HHV) and the lower heating value (LHV) of hydrochars for 58 % and 65 % in comparison with SMS, respectively. Analysis of morphology and functional groups showed the formation of microspheres and cracks on the hydrochar surface, which are predominantly dominated by aromatic and oxygen-rich functional groups. Thermal and kinetics analysis showed that HTC treatment improves the combustion behavior of the obtained solids. Combustion kinetic parameters of SMS and hydrochars were determined by the methods of Kissenger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters and pre-exponential factors reveal a complex mechanism of SMS and hydrochars decomposition process
Thermal and XRD analysis in characterization of bentonite modified with different amounts of surfactant
No full textOrganobentonites are usually synthesized by intercalating various long chain organic cations (surfactants) into the interlayer space of bentonite by ion exchange with naturally occurring exchangeable cations. Presence of surfactants in the interlamellar space of bentonite changes its surface properties from hydrophilic to hydrophobic [1].
In this study, results on characterization of organobentonites obtained by treatment of Ca/Na bentonite with different amounts of surfactant – octadecyldimethylbenzyl ammonium chloride – ODMBA (10, 20, 30, 50 and 100 % of cation exchange capacity of Ca/Na bentonite) are presented. Organobentonites are denoted as OB-10, OB-20, OB-30, OB-50 and OB-100 [2]. Characterization of organobentonites were done by XRD [2] and thermal (DTA/TG) analyses. DTA curves as well as the data for mass loss from TG curves of Ca/Na bentonite and organobentonites are presented in the graphical abstract. DTA/TG analysis can be used to differentiate peaks associated with weight loss and those associated with phase transition and is widely used in the study of thermal reactions of the natural clay minerals (e.g. Ca/Na bentonite). These reactions include dehydration, dehydroxylation as well as transformation of the clay to a meta-phase and recrystallization of the meta-phase into a crystalline phase. The first two reactions are endothermic whereas the recrystallization of the meta-phase is exothermic [3]. In the DTA curves of the organobentonites, additional intensive exothermic peaks at temperatures >300ºC were observed representing oxidation of the organic matter present in the interlayer space of clay. The relative intensity of these exothermic peaks increase with increasing amounts of ODMBA in organobentonite. From mass loss, it can be seen that when organic cations are present in the interllamelar space of clay, mass loss in the first temperature region is lower confirming that treatment of Ca/Na bentonite with ODMBA ions increase hydrophobicity of the clay surface
Thermal kinetic analysis of the spent mushroom substrate and hydrochar
No full textA carbon-rich product, hydrochar, was synthesized by hydrothermal carbonization (HTC) of spent mushroom substrate (SMS), at temperature of 260 °C. The thermal kinetic analysis has shown that hydrothermally treatment improve the combustion behavior of hydrochar. The kinetic parameters were determined by Kissinger and Ozawa methods. The SMS-260 had a significantly lower activation energy compared to the SMS, which means that this hydrochar needs a smaller amount of energy to start combustion. Generally, the preliminary results show that HTC is an effective way to transform SMS into alternative solid biofuel
Application of mechanochemically activated sodium carbonate in environmental protection
No full textSodium carbonate samples were mechanically activated in a vibro mill. The increase in the
free surface area of the activated samples was monitored by the BET method, and the state of the crystal
lattice by the diffraction method. The analysis of the results showed a significant increase in the free
surface of the activated material as well as significant changes in the crystal structure of the samples due
to grinding in a vibro mill. Such activation of sodium carbonate would enable a significant increase in the
sorption properties of sodium carbonate and thus its application in environmental protection
Assessment of sorption capability of alginate immobilized peach stone particles for lead removal from water
No full textFruit waste produced in huge quantities from the food and agriculture industries causes numerous difficulties in landfills due to their high biodegradability. The reuse of this waste is one of the future requirements for accomplish economic and environmental sustainability. Recent studies have shown that with appropriate modifications (chemical, physical or thermal) this material can be used to obtain a high-quality biosorbent to remove pollutants from wastewater. In this paper, peach stone (Prunus Persica L) particles (PS), as a part of fruit industrial organic waste, were immobilized in sodium alginate (PS-A) and utilized to remove lead from water solutions. The PS-A was characterized and analyzed by Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy-attenuated total reflection (FTIR-ATR); contact pH and pHpzc were done as well. The effect of operating parameters such as contact time, mass to volume ratio, and pH on the performance of Pb removal in the batch reaction system was investigated. The experimental data were fitted by appropriate kinetic models. The results from this paper indicate that PS-A particles have the potential to be applied as an effective adsorbent of lead ions from an aqueous solution
Removal of diesel pollution by biochar – support in water remediation
No full textWater contaminated with diesel oil is one of the great challenges in waste water management. It is crucial to remove the water soluble fractions (WSF) from water in order to avoid toxic effects of these compounds and to meet the discharge regulations set by the environmental authorities. Biochar sorbents have generated a lot of attention as a new type of material due to their low cost origin and surface properties which lead to exceptionally high sorption capacities in water-pollution separation process. In this study, we have reported the synthesis and characteristics of novel biochar sorbent made from waste lignocellulosic biomass (peach stones) and evaluated its possible application in removal of WSF from synthetic wastewater. The synthesized biochar materials were characterized using scanning electron microscopy (SEM), Fourier (FTIR) and Brunauer, Emmett and Teller (BET) technique, while the elemental analysis was also done. Characterisation of peach stone biochar (PS-B) indicated multi porous high surface area (159.1 m2/g), with an average pore diameter of 2.66 nm. FTIR results indicated the presence of more aromatic compounds in biochar compared to peach stones. The sorption experiments were performed in batch system with mixing, with initial WSF of diesel components of 20 mg/L. The application of peach stone biochar (PS-B) resulted in more than 95% removal of diesel WSF, with reaching equilibrium after 5h of contact (under described operational conditions). Sorption mechanism can be described as multilayer chemisorption process, well described by Freundlich equation, which was also confirmed by pseudo-second order equation. Ecotoxicology tests have shown a decrease of toxicity of contaminated water on A. fischeri after the treatment of water by biochar sample. Therefore these forms of carbon based sorbents have great potential to be good sorbents of petroleum hydrocarbons WSF and can be successfully applied for their removal in water treatment
Dobijanje hidročađi iz industrijskog useva Miscantus x giganteus kao čvrstog biogoriva i komponente preparata za dalju primenu u zaštiti životne sredine
No full textInvestigation of bentonite characteristics for application in geopolymers and hybrid cement binders
No full textSince the late seventies of twentieth century geopolymers have been investigated as a new type of aluminosilicate binders which will eventually replace traditional cement based structural materials. Geopolymers are the three-dimensional synthetic inorganic polymers, which contain amorphous and semi-amorphous crystal microstructures. Hybrid binders are structural materials which combine alkali activated raw materials and cement in its mixdesign. In this paper the characteristics of bentonite, which are important for its application in geopolymers and hybrid cement binders, were thoroughly investigated in order to evaluate its proneness to alkali activation. Bentonite samples from three different deposits were submitted to detail testing. Elaborate physico-chemical and mineralogical characterization was The Nineth Serbian Ceramic Society Conference »Advanced Ceramics and Application« September 20-21, 2021 Serbian Academy of Sciences and Arts, Knez Mihailova 35, Belgrade, Serbia 83 conducted. Determined moisture contents in bentonite samples were from 20.54 % to 24.15 %. Hygroscopic moisture was in range 7.99 - 8.99 %, and specific mass was in range 2.42 - 2.52 g/cm3 . Grain-size analysis of the bentonite samples was conducted using Sympatec laser sizer. Mineralogical analysis highlighted smectite, α-crystbalite, quartz, and feldspar as the most aboundant mineral phases. DTA/TG analyses were conducted to monitor thermal behavior of the bentonite samples in thermal range 20 – 1000 °C. Cation exchange capacity, CEC, (Ca2+, Mg2+, Na+ , and K+) was also conducted. Obtained total CEC values were from 66.16 meq/100g to 78.97 meq/100g. Plasticity of bentonite samples was determined using Atterberg – Casagrande methodology. Also Moisture absorption coefficient (using Enslin –Neff methodology), pH values and dioxin content in samples were tested. It was determined that investigated bentonite samples showed high potential for application in construction materials, i.e. geopolymers and hybrid binders
