NOVI EKOLOŠKI PRIHVATLJIVI I JEFTINIJI ADITIVI ZA ISPLAKE NA BAZI VODE

This study investigates the possibility of using rice husk ash as an additive to develop an environmentally friendly and low-cost drilling fluid system. Rice husk ash was added as an additive to water-based bentonite drilling fluids at different concentrations ranging from 2 wt% to 15 wt%. The rheological and filtration properties of each developed drilling fluid were measured by using a viscometer and standard low-pressure low-temperature filter press. Subsequently, the cutting carrying index, the minimum annulus velocity required to clean the bottom of the well efficiently, the flow behaviour index and the permeability of mud cakes of the formulated systems were calculated in order to assess the performance of the systems. The results demonstrated that the rheological and properties were improved depending on the concentration of the rice husk ash introduced. With the introduction of 15 wt% concentration of rice husk ash, while apparent viscosity and yield point increased by 60% and 183%, respectively, thixotropy and plastic viscosity decreased by 29% and 63%, respectively. On the other hand, drilling fluid with 4% wt% content of rice husk ash reduced the fluid loss by 10%. Moreover, the results showed that cutting the carrying index, the minimum annulus velocity required to clean the bottom of the well efficiently and the flow behaviour index of the enhanced with the exploitation of the rice husk ash in the drilling fluid. This study showed that rice husk ash is a promising additive to use in water-based bentonite drilling fluids when properly implemented, and hence reduces the impact on the environment, and the total cost for drilling.Istražene su mogućnosti upotrebe pepela rižine ljuske kao aditiva za pripremu ekološki prihvatljivijih i jeftinijih isplaka. Pepeo rižine ljuske dodan je u bentonitnu isplaku u različitim koncentracijama u rasponu od 2 do 15% maseno. Reološka i filtracijska svojstva pripremljenih isplaka mjerena su upotrebom viskozimetra i standardne API filtar preše. Naknadno, kako bi se bolje procijenila svojstva ispitivanih isplaka određen je indeks iznošenja krhotina, minimalna brzina protjecanja isplake u prstenastome prostoru potrebna za efikasno čišćenje dna bušotine, indeks toka te propusnost isplačnoga obloga. Dobiveni rezultati upućuju na poboljšanje reoloških i ostalih svojstava ispitivanih isplaka u ovisnosti o korištenoj koncentraciji pepela rižine ljuske. Kod isplake u koju je dodano 15% maseno pepela rižine ljuske uočeno je povećanje prividne viskoznosti za 60% i naprezanja pri pokretanju za 183%, dok su tiksotropna svojstva i plastična viskoznost smanjeni za 29 % odnosno 63%. S druge strane, kod isplaka koje su pripremljene s 4% maseno pepela rižinih ljuski izmjereno je smanjenje filtracije za 10 %. Štoviše, rezultati upućuju na poboljšanje indeksa iznošenja krhotina, smanjenje minimalne vrijednosti brzine protoka u prstenastome prostoru za efikasno čišćenje dna bušotine i vrijednosti indeksa toka kod upotrebe pepela rižinih ljuski u isplaci. Ovo istraživanje jasno pokazuje da je pravilnom primjenom pepela rižinih ljuski kao aditiva u bentonitnoj isplaci moguće smanjiti utjecaj na okoliš i troškove bušenja

Calcination and Pelletizing of Siderite Ore

In the present study, calcination properties of Hekimhan-Deveci siderite (FeCO3) ore and the effect of calcination process before the pelletization on strength of pellet were investigated and evaluated. Two different calcination processes were followed. One of them is the traditional calcination process and the other one is microwave assisted calcination process which is a new process for siderite ore. The characterization of the calcined and uncalcined siderite ore was done using X-ray diffraction, X-ray fluorescence spectrometry and thermogravimetric analysis. The physical and mechanical properties of pellets which were obtained using the raw siderite and the calcined siderite were compared with each other. As a result of experimental studies, it was found that the calcination process decreased the milling time, causing the significant energy saving and the most suitable calcination process for siderite ore was found as 15 min at 700°C temperature. It was the first time that the calcination process of the siderite ore was achieved by microwave by adding 30 wt% sucrose as a thermal auxiliary. The microwave conditions were determined as 900 W at 3 min. In 3 min, the temperature of the siderite ore increased up to 1100°C and 32.14% weight loss for the sample was achieved

Farklı sentez yöntemleri ile lityum triborat sentezi ve karakterizasyonu ve ısısal ışıldama özellikleri.

Lithium triborate, (LiB3O5), is a technologically important material for diverse applications, such as nonlinear optical materials and surface acoustic wave devices or, etc. Furthermore, it is suggested as an efficient thermoluminescent material. LiB3O5, suitable to dosimetric usage, was produced by different synthesis methods which were high temperature solid state reaction, microwave solid state reaction, microwave assisted high temperature solid state reaction and precipitation assisted high temperature solid state reaction. After the synthesis, metal oxides were doped into LiB3O5 to enhance its thermoluminescent properties. Identification and characteristics of LiB3O5 were determined by X-ray diffraction (XRD), Fourier Transform Infra red (FTIR) analyses, Differential Thermal Analyses (DTA), Scanning Electron Microscopy (SEM) and Particle Size Analyzer. The glow curves were obtained by using thermoluminescent (TL) reader. Among four different synthesis methods applied, high temperature solid state method needs very high temperatures and long duration of heating. Therefore, the effect of the reaction temperature, the time intervals, and also starting materials on production of LiB3O5 were investigated. Characterization studies indicated that LiB3O5 could be produced at 710 °C for 4 hours. Among the starting materials used, Li2CO3 and H3BO3 combination was found the most suitable for the synthesis of LiB3O5 considering phase impurity as well as cost. LiB3O5 synthesized by microwave energy was unsuccessful. However, LiB3O5 could be synthesized by microwave assisted synthesis method by adding distilled water, urea and sucrose separately as thermal auxiliaries in microwave pre-heating step. The use of microwave and conventional ovens subsequently shortened the duration of heating. The crystallinity of LiB3O5 was the best in 40 % sucrose addition to initial mixture. The best method for synthesis of LiB3O5 has been found as precipitation assisted high temperature solid state method. This method yields LiB3O5 with higher phase purity as compared to these produced by other methods applied in this thesis and reported in the literature. It seems to be rather attractive since it is simple and needs less energy. Rare earth metal oxides, CuO and Al2O3 were added to LiB3O5 as activators to improve its TL properties. LiB3O5 synthesized by precipitation assisted high temperature solid state reaction and doped by 5 % wt Al2O3 showed the best TL property. Its main dosimetric characteristics revealed that LiB3O5 seemed to be suitable to medical and radiotherapy applications, since it was non-toxic, tissue equivalent, and chemically inert to body fluids.Ph.D. - Doctoral Progra

Investigation of Mechanical Properties of Self Compacting Lightweight Concretes Produced Using Van Pumice and Waste Marble Dust

Bu çalışmada, Van yöresi pomzası ve mineral katkı olarak da mermer tozu kullanılarak kendiliğinden yerleşen hafif beton üretimi yapılmıştır. Toplam olarak 5 farklı beton karışımı üretilmiştir. Mermer tozu, çimentoyla %0, %5, %10, %15 ve %20 oranlarında yer değiştirilerek kullanılmıştır. Tüm karışımlarda su/bağlayıcı oranı ve toplam bağlayıcı miktarı sabit tutulmuştur. Öncelikle taze betonlar üzerinde, çökme- yayılma, T50 süresi, V hunisi ve L kutusu deneyleri yapılarak sonuçlar mermer tozu eklenmeden üretilen betonlarla karşılaştırılmıştır. Daha sonra 23±2°C suda kür edilen 7 ve 28 günlük küp numunelere basınç dayanımı, yarmada çekme dayanımı, ultrases geçiş hızı ve birim hacim ağırlık deneyleri uygulanmıştır. Çalışma sonucunda %15 oranında mermer tozu ilavesinin kendiliğinden yerleşen beton üzerinde olumlu etkisi olduğu gözlenmiştir. Ayrıca mermer tozunun kendiliğinden yerleşen hafif beton üretiminde değerlendirilmesi ile bu atıkların çevreye verdikleri olumsuz etkiler azaltılacak ve ekonomik fayda sağlanacaktır.In the present study, self compacting lightweight concrete was mainly produced by pumice collected from Van Basin adding waste marble dust as mineral additive. Total of five different concrete mixtures were produced replacing cement as the ratio of %0, %5, %10, %15 and %20. The water/binder ratio and amount of total binder were kept constant in all mixtures. Slump-flow, T50, V-funnel and L-box tests were made for fresh concretes and the results were compared with each other. After that, physical properties of all fresh concretes with cube specimens, which were de-moulded and located in standard 23±2°C water cured strenght, unit weight and ultra-sound velocit tests. It is concluded that the addition of %15 waste marble dust increases the properties of self compacting lightweight concrete positevely . Using waste marble dust as a mineral additive may contribute not only economic benefits for production of self compacting lightweight concrete but also decreasing the environmental impact of waste

The effect of different starting materials on the synthesis of lithium triborate

Lithium triborate (LiB3O5) was synthesized using different starting materials. The effect of these materials on the phase purity of LiB3O5 was investigated in each case. Identification and. characterizations of the products were carried out by powder X-ray diffraction (XRD) and infrared (IR) analyses. The present study showed that the starting materials play an important role in the synthesis of lithium triborate with respect to phase impurity

PRIPREMA I ISPITIVANJE ISPLAKE NA BAZI VODE U SVRHU SMANJENJA SKLONOSTI DIFERENCIJALNOM PRIHVATU

The objective of the study is to design a drilling fluid that prevents differential pressure pipe sticking tendency caused by drilling fluid with fly ash that is an industrial waste generated from the combustion of coal. To this end, drilling fluid samples were prepared with different particle sizes obtained through the sieving and grinding process and increasing concentrations of fly ash. Differential pipe sticking tests of the samples were performed by applying 3.447 MPa (500 psi) pressure and using a Fann Model 21150 Differential Sticking Tester in order to determine how the coefficient of sticking and torque reading varied with the fly ash. From the results, it was observed that the coefficient of sticking and torque reading of the water-based drilling fluids decreased up to a specific concentration as the concentration of fly ash increased. Furthermore, particle size analysis illustrated that the coefficient of sticking and torque of the drilling fluid differs depending on the particle size of fly ash introduced. The drilling fluid designed with ground fly ash demonstrated lower sticking coefficient and torque reading than that of drilling fluids formulated with raw and sieved fly ashes. The experimental study revealed that fly ash is a promising additive in the mitigation of differential sticking tendency caused by water-based drilling fluids.Cilj je ovoga istraživanja pripremiti isplaku uz dodatak lebdećega pepela, koji je industrijski otpad dobiven izgaranjem ugljena, koja će spriječiti pojavu diferencijalnoga prihvata bušaćih alatki. Ispitani su uzorci isplake koji su pripremljeni s različitim koncentracijama i veličinama čestica lebdećega pepela, dobivenim mljevenjem i prosijavanjem. Ispitivanje sklonosti diferencijalnom prihvatu u različitim uzorcima isplake provedeno je pri tlaku 3,447 MPa (500 psi) korištenjem uređaja Fann Model 21150, pri čemu je praćena promjena koeficijenta ljepljivosti i očitanja torzije s dodavanjem lebdećega pepela. Iz rezultata je vidljivo da se koeficijent ljepljivosti i očitanje torzije smanjuju s povećanjem koncentracije lebdećega pepela u isplaci. Nadalje, istraživanje je pokazalo da i koeficijent ljepljivosti i torzija ovise o raspodjeli veličine čestica lebdećega pepela u isplaci. Isplaka pripremljena s mljevenim lebdećim pepelom pokazala je niži koeficijent prianjanja i manje očitanje torzije u odnosu na isplake pripremljene s nemljevnim („sirovim”) ili prosijanim lebdećim pepelom. Istraživanje je pokazalo da bi se lebdeći pepeo mogao koristiti kao aditiv za smanjenje sklonosti diferencijalnom prihvatu u isplakama na bazi vode

The thermoluminescent properties of lithium triborate (LiB3O5) activated by aluminium

In this paper, the thermoluminescence (TL) dosimetric characteristics of Al-doped LiB3O5 compounds are presented. The powder samples were prepared by the solid-state reaction method and the formation of the compounds were confirmed by an X-ray diffraction study. The TL studies of undoped and Al-doped LiB3O5 samples showed similar glow curve structures. They have three TL glow peaks at about 60, 130 and 200 degrees C after heating at a constant heating rate of 1 degrees C/s. Their comparative TL studies indicated that 5 wt% Al-doped LiB3O5 compound was approximately 240 times more sensitive than undoped compound. The TL emission spectra of Al-doped LiB3O5 showed a maximum band at around 520 nm. The main dosimetric characteristics, which are namely the TL dose response, TL sensitivity, fading, minimum detectable dose, reproducibility, precision of dose measurement and annealing procedure, indicated that Al-doped LiB3O5 sample, can be used in dosimetric applications. The trap parameters namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the glow peaks in beta irradiated undoped and Al-doped LiB3O5 samples were obtained by glow curve deconvolution (GCD) program

Synthesis of a Multifunctional Quinoxaline and Benzodithiophene Bearing Polymer and Its Electrochromic Device Applications

A quinoxaline (Qx) and benzodithiophene (BDT) comprising of random copolymers, namely poly(5-(6-(5-(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b ']dithiophen-2-yl)-4-(2-ethylhexyl)thiophen-2-yl)-4,8-bis ((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b ']dithiophen-2-yl)-2,3-bis(3,4-bis(octyloxy)phenyl)quinoxaline) (PQBT), is synthesized via Stille polycondensation reaction. To investigate the effect of the pi-bridge on the electrochromic properties, 3-(2-ethylhexyl) thiophene is incorporated the between Qx and BDT moiety. The resulting random copolymer is characterized by NMR spectroscopy, gel permeation chromatography (GPC), attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). PQBT exhibits ambipolar and multichromic characteristics and is highly soluble in common solvents. Optoelectronic studies reveal two well-separated absorption bands having maxima at 500 and 532 nm with 1.83 eV optical band gap (E-g(op)). PQBT exhibits orange color in the neutral state with brown, green, and blue colors in the intermediate, oxidized, and reduced states, respectively. Subsequently, a PQBT and poly-3,4-ethylenedioxythiophene (PEDOT)-bearing prototype bilayer electrochromic device working between orange and blue colors is constructed and characterized

Synthesis of a Multifunctional Quinoxaline and Benzodithiophene Bearing Polymer and Its Electrochromic Device Applications

A quinoxaline (Qx) and benzodithiophene (BDT) comprising of random copolymers, namely poly(5-(6-(5-(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b ']dithiophen-2-yl)-4-(2-ethylhexyl)thiophen-2-yl)-4,8-bis ((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b ']dithiophen-2-yl)-2,3-bis(3,4-bis(octyloxy)phenyl)quinoxaline) (PQBT), is synthesized via Stille polycondensation reaction. To investigate the effect of the pi-bridge on the electrochromic properties, 3-(2-ethylhexyl) thiophene is incorporated the between Qx and BDT moiety. The resulting random copolymer is characterized by NMR spectroscopy, gel permeation chromatography (GPC), attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). PQBT exhibits ambipolar and multichromic characteristics and is highly soluble in common solvents. Optoelectronic studies reveal two well-separated absorption bands having maxima at 500 and 532 nm with 1.83 eV optical band gap (E-g(op)). PQBT exhibits orange color in the neutral state with brown, green, and blue colors in the intermediate, oxidized, and reduced states, respectively. Subsequently, a PQBT and poly-3,4-ethylenedioxythiophene (PEDOT)-bearing prototype bilayer electrochromic device working between orange and blue colors is constructed and characterized

Non-fullerene organic solar cells based on thienopyrroledione comprising random copolymers; effect of alkyl chains

Two new random copolymers, signed as P1 and P2, were designed and synthesized. 5-(2-ethylhexyl)-4Hthieno[3,4-c]pyrrole-4,6(5H)-dione (TPD) was utilized as electron-accepting moiety whereas selenophenewas utilized as spacer, 4,8-bis[5-(2-ethylhexyl) thiophen-2-yl]-2,6-bis(trimethylstannyl)benzo[1,2-b:4,5-b’](BDT(TiC8)), thiophene and alkylthiophene were utilized as donor moieties. Structural analyses of thepolymers were carried out by attenuated total Reflectance-Fourier-transform infrared spectroscopy(ATR−FTIR). Weight-average and number-average molecular weights (Mw, Mn) of the polymers weredetermined via size exclusion chromatography (SEC). Electrochemical and spectroelectrochemicalmeasurements were performed to investigate optoelectronic properties. The polymers were used asdonor polymers in active layer to fabricate non-fullerene, bulk heterojunction (BHJ) organic solar cells(OSCs). BHJ solar cells' device structure is ITO/PEDOT: PSS/Active Layer/LiF/Al, where active layer consistsof ITIC as acceptor and thienopyrroledione containing donors. Various optimization studies (solventselection, donor: determination of acceptor ratio, active layer’s mass ratio optimizations, determinationof the active layer's thickness, additive selection and thermal annealing) were carried out to obtain thebest performance from the devices. The device based on P1: ITIC (1:1) blend with a thickness of 161 nmgave the best performance with a power conversion efficiency (PCE) of 7.94 %. The highest PCE obtainedfrom P2 based organic solar cell is 1.96 %. P2 exhibited low solubility attributed to the lack of alkyl groupsenhancing polymer solubility, electronic properties, and photovoltaic performances. Our study representsa synthetic approach to exhibit alkyl chains' effect on OSCs' performance based on TPD containing randompolymers and non-fullerene acceptors.Two new random donor-acceptor (D-A) copolymers, signed as P1 and P2, were designed and synthesized. Electrochemical and spectroelectrochemical measurements were performed to investigate absorption, energy levels, electronic and optical band gaps for comparison. The polymers were used as donor polymers in the active layer to fabricate non-fullerene, bulk heterojunction (BHJ) organic photovoltaics (OPVs). Investigations were carried out through the conventional BHJ structure; ITO/PEDOT: PSS/Active Layer/LiF/Al, where active layer consists of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC) as the acceptor and thienopyrroledione containing donors. The device based on P1:ITIC(1:1) blend with a thickness of 161 nm gave the best performance with a power conversion efficiency (PCE) of 7.94%, an open-circuit voltage (VOC) of 0.86 V, a short-current density (JSC) of 18.45 mA cm−2 and a fill factor (FF) of 50.12%. The highest PCE obtained from P2 based organic solar cell is 1.96%. P2 exhibited low solubility attributed to the lack of alkyl groups enhancing polymer solubility, electronic properties, and photovoltaic performances. The research outputs exhibit that introduction of alkyl chains on the polymer backbone can enhance device performance