Nilufer Durmaz Hilmioglu

Pervaporation of ethanol/water mixtures by zeolite filled sodium alginate membrane

Abstract For a few decades, pervaporation (PV) has been considered as an energy saving, environmentally friendly and cost effective separation technique which separates close boiling point, azeotropic and thermally sensitive components. It is clearly well known that the PV has significant advantages in azeotropic mixtures separation where distillation needs an entrain solvent which must be removed in the following steps. The most important part of PV is the selection of the appropriate membrane. The inadequate selectivity and low flux values limited the expansion of this process. It is always assumed that efficient pervaporation means a membrane with good permeability and selectivity. In this work, sodium alginate (NaAlg) was used as the membrane material. Pristine NaAlg and zeolite 4A filled NaAlg mixed matrix membranes (MMMs) have been prepared by solution casting evaporation and cross-linking method. Phosphoric acid (PA) was used as the cross-linking agent. The morphologies of the membranes were studie...

Bioethanol recovery using the pervaporation separation technique.

Purpose – The purpose of this paper is to demonstrate applicability of the pervaporation technique for separation ethanol/water mixtures.Design/methodology/approach – For the purposes of membrane material development for pervaporation zeolite filled and unfilled cellulose acetate membranes were prepared. Zeolite types were 4A, 13X. The effect of incorporation of nano‐sized zeolites prepared in a colloidal form in membranes was also investigated. Equilibrium sorption experiments were carried out. Degrees of swelling were calculated at different liquid feed mixture compositions for separating an azeotrope forming mixture, ethanol/water by pervaporation.Findings – Zeolite 13X filled CA membrane may have the better pervaporation performance than zeolite 4A filled CA membrane. From the sorption tests it is concluded that ethanol/water azeotropy can be achieved by pervaporation.Practical implications – Application of CA membranes in industrial scale pervaporation units may be feasible for separation of ethanol/...

Pervaporative desalination of seawater by using composite and blended poly(vinyl alcohol) membranes

In this study, pervaporative separation capability of poly(vinyl alcohol) (PVA) based different membranes were investigated. Pristine, zeolite-loaded and blended PVA membranes were prepared by solution-casting and cross-linking method. Zeolite 3A was used to make PVA more stable and durable during the different operation conditions. Sodium alginate has strong hydrophilic bond structure so it was used to enhance water flux. Flux and salt retention values were investigated over temperature range of 293‐313 K. Pervaporation performances were evaluated as function of flux and salt retention. At low temperature, ion passage was prevented and 100% salt retention was achieved by all membrane types. As the temperature increased from 293 to 318 K, salt retention dramatically decreased. Increasing zeolite loading positively affected the water flux. Also, blended membrane gave better flux results than pristine PVA.

Pervaporative separation of isopropyl alcohol/water mixtures: effects of the operation conditions

Abstract Isopropyl alcohol/water mixture was separated by an environmentally friendly membrane process: pervaporation. Pervaporation experiments were carried out with a polymer blend membranes of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) at different temperatures. PVA/PAA cross-linked membranes were prepared with different blend ratios. The influence of PVA/PAA ratio and of liquid mixture composition were investigated. The apparent activation energies were calculated at different temperatures. With increasing PAA content in the membranes fluxes decreased and selectivities increased. The flux increased with increasing operation temperature, as selectivity decreased. The studies showed that isopropylalcohol/water mixtures can be separated by pervaporation which is an energy efficient technology using the prepared membranes.

Fuel bioadditive production by chitosan/sulfosuccinic acid catalytic membrane

ABSTRACT Global warming is one of the biggest environmental problems of late. The use of renewable raw material resources as biomass and its conversion into alternative energy resources have attracted considerable attention during the recent years. Ethyl levulinate (EL) is a kind of fuel bioadditive for use in diesel and biodiesel engines, which is produced by the esterification of ethanol and levulinic acid. In the present study, sulfosuccinic acid (SSA) catalysts supported on chitosan catalytic membrane is used for the synthesis of EL. The effects of temperature, catalyst amount, and molar feed ratio were studied.

Review of Renewable Biofuels in the Aviation Sector

The air transport industry has a significant effect on air pollution. Usage of petroleum-derived fuels is responsible for greenhouse gas emissions. Also, these fuels have a high cost. Therefore, development of alternative biofuel from renewable feedstock gains importance. Renewable and sustainable biofuels must be produced and used for the all vehicle engines. This study is related to the synthesis of biofuels and production process. Renewable feedstocks, biofuels, and their production processes are explained.

Improvement of fuel properties of biodiesel with bioadditive ethyl levulinate

Abstract Biodiesel has poor cold flow properties due to their high saturated fatty acid content. Ethyl levulinate is used as bio-based cold flow improver additive in biodiesel. In this work, both ethyl levulinate and biodiesel were synthesized in the laboratory. Ethyl levulinate was added to the biodiesel at different rates, i.e, 5, 10, 15, 20 (vol %). The effect of ethyl levulinate addition on density, kinematic viscosity, acid value, cloud point and pour point was determined and compared to the EN 14214 and ASTM D6751 specification. Consequently, ethyl levulinate appears acceptable as a cold flow improver for biodiesel fuel.

Uçaklarda Buzlanma ve Buzlanmayı Önleyecek Yöntemler

Ucaklarin kanatlari uzerinde ki kar ve buz birikintileri ucus performansini etkileyerek ucusun elverissiz hale gelmesine sebep olur ve kalkis yapmasini engeller. Bu sebeple buzlanma havacilik sektorunde onemli bir meteorolojik tehlikedir. Ucus yuksekligi, hava kosullari, nem, sicaklik gibi cevresel faktorler buzlanmayi onemli derecede etkiler. Buzlanma yolcularin hayatini tehlikeye sokacak sonuclara sebep olabilecegi icin tehlikeli bir durumdur. Dolayisiyla buzlanma olayinin sebepleri, neden oldugu olumsuz sonuclar ve buzlanmayi engelleme veya buzlanmanin olumsuz sonuclarini ortadan kaldirma calismalari hem insan hayati bakimindan hem de teknolojik acidan onemli bir yere sahiptir. Bu calismada buzlanma olusumunu ortadan kaldirmak icin kullanilan buzlanma onleyici ve engelleyici kimyasallar, yapi malzemeleri arastirilmistir

Anhydrous fuel ethanol production by a combined hydrophobic–hydrophilic pervaporation system

ABSTRACT In this study, a hybrid bioethanol production and purification system was designed and operated at different operation conditions. In the first stage, dilute ethanol (3 wt%) was produced by fermentation and concentrated to 80 wt% ethanol–water mixture by means of poly(dimethylsiloxane) membrane. In the second stage, residual water was purified to approximately 99% water content by using carboxymethyl cellulose membrane. The first stage is a fermentor, so the temperature was kept stable at 25°C. Effects of the operation variables such as temperature and concentration of the mixture on membrane separation performance were evaluated.

Bioadditive Synthesis from Glycerol by Esterification Using Catalytic Chitosan Membrane

Glycerol is the main by-product in biodiesel production. The increasing production of biodiesel has resulted in significant amount of glycerol deposition. Esterification of glycerol with acetic acid is a kind of method to consume excess glycerol. The valuable chemicals like that bioadditives are produced in this method. Zr(SO4)2·4H2O loaded chitosan catalytic membrane was prepared by the solution casting method and used as catalyst for esterification of glycerol and acetic acid. The reactions were performed in a batch reactor and in a pervaporation catalytic membrane reactor (PVCMR). The structure of the membranes was investigated by means of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results of esterification of acetic acid and glycerol show that the conversion was slightly improved with the Zr(SO4)2·4H2O content in the membrane at a fixed chitosan content. The reaction rate constant increased with increasing acetic acid/glycerol molar ratio, amount of catalyst loading in the catalytic membrane and reaction temperature. Higher conversion values were obtained by PVCMR.