beta
NaslovChemical & biochemical engineering quarterly : the international publication of "Kemija u industriji" : the official journal of Croatian Society of Chemical Engineers, Faculty of Chemical Engineering and Technology University of Zagreb, Slovenian Chemical Society, and Austrian Association of Bioprocess Technology : 33,1(2019) / Co-Editors-in Chief: M. Rogošić, B. Zelić.
ImpresumZagreb : Croatian Society of Chemical Engineers, 2019.
Materijalni opis1 online jedinica građe.
ZbirkaDigitalna zbirka Croatica - obvezni primjerak
ID000622963
Vrsta publikaciječasopis; neomeđena građa
  
rrep
 
14 (1-10)
NaslovPhysicochemical properties, cytotoxicity, and antioxidative activity of natural deep eutectic solvents containing organic acid / Anamarija Mitar, Manuela Panić, Jasna Prlić Kardum, Jasna Halambek, Aleksandra Sander, Kristina Zagajski Kučan, Ivana Radojčić Redovniković, Kristina Radošević.
Materijalni opisGraf. prikazi.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisNatural deep eutectic solvents (NADES) may be considered ‘designer solvents’ due to their numerous structural variations and the possibility of tailoring their physicochemical properties. Prior to their industrial application, characterization of NADES is essential, including determination of their physicochemical properties, cytotoxicity, and antioxidative activity. The most important physicochemical properties of eight prepared NADES (choline chloride:malic acid, proline:malic acid, choline chloride:proline:malic acid, betaine:malic acid, malic acid:glucose, malic acid:glucose:glycerol, choline chloride:citric acid, and betaine:citric acid) were measured as functions of temperature and water content. In general, the structure of prepared NADES greatly influences their physical properties, which could be successfully modified and adjusted by addition of water. All tested NADES were absolutely benign and noncorrosive for investigated steel X6CrNiTi18-10. Furthermore, cytotoxicity of prepared solvents was assessed toward three human cell lines (HEK-293T, HeLa, and MCF-7 cells), and antioxidative activity was measured by the Oxygen Radical Absorbance Capacity (ORAC) method. With regard to cell viability, all tested NADES containing carboxylic acid could be classified as practically harmless and considered environmentally safe. The ORAC values indicated that the tested NADES displayed antioxidative activity.
rrep
1
NaslovUltrasonically facilitated electrochemical degradation of acetaminophen using nanocomposite porous cathode and Pt anode / Reza Darvishi Cheshmeh Soltani, M. Mashayekhi.
Materijalni opisIlustr.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisIn the present research study, an electrochemical process (EC) equipped with a porous cathode was combined with ultrasound (US) to efficiently degrade acetaminophen (ACE) as the target pollutant. The carbonaceous porous cathode was used for in situ generation of hydrogen peroxide. The generation of hydrogen through the cathodic reduction was current-dependent. As a result, the combination of US with EC resulted in the highest degradation efficiency (%) of 74.6 %. Increasing the concentration of Na2SO4 (as supporting electrolyte) from 0.01 to 0.1 M led to enhanced ACE degradation efficiency (%) from 50.6 to 75.7 %, respectively, while a significant drop in ACE removal efficiency from 93.0 to 22.0 % occurred when the initial concentration of ACE increased from 1 to 10 mg L–1, respectively. The operation of US/EC with pulse mode of US irradiation led to a slight increase in ACE degradation efficiency (%) (79.0 %). The presence of halide compounds (chloride ions) significantly enhanced the removal of ACE (96.1 %), while alcoholic compounds, especially methanol, produced a substantial suppressive effect on the treatment of ACE.
rrep
2
NaslovTreatment of bisphenol-A using sonication-assisted photo-fenton hybrid process : influence of reaction parameters / Meral Dükkancı.
Materijalni opisIlustr.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisSonication-assisted photo-Fenton oxidation of an endocrine disrupting compound, bisphenol-A (BPA), was studied under visible-light irradiation in the presence of a LaFeO3 perovskite catalyst. The effects of the parameters: initial BPA concentration ([BPA]0), H2O2 concentration ([H2O2]0), catalyst loading, initial pH of the BPA solution, and reaction temperature were studied on the sonication-assisted photo-Fenton oxidation of an aqueous BPA solution. The optimum conditions for the oxidation were determined to be: [BPA]0 = 10 ppm, [H2O2]0 = 4.8 mM, catalyst loading = 0.75 g L–1, pH = 2.6, temperature = 313 K. During all runs, sonication power of 40 W, visible lights power of 150 W+150 W, BPA solution volume (0.5 L), and stirring speed of 500 rpm were kept constant. Under these conditions, degradation of 56.3 %, COD removal of 50.9 %, and TOC removal of 15.6 % were achieved after 6 h of reaction. The small amount of iron that leached into the solution indicated high stability of the catalyst. The sonication-assisted photo-Fenton oxidation of BPA was described by the second order kinetics with an activation energy of 15.34 kJ mol–1. Toxicity tests were also performed and the results revealed that the intermediates formed in the sonication-assisted photo-Fenton oxidation of BPA were less toxic compared to the parent BPA molecule at a neutral pH value. However, the same interpretation was not valid at the acidic pH of 2.6.
rrep
3
NaslovEffects of phosphorus on loosely bound and tightly bound extracellular polymer substances in aerobic granular sludge / L. L. Yan, L. B. Yu, Q. P. Liu, X. L. Zhang, Y. Liu, M. Y. Zhang, S. Liu, Y. Ren, Z. L. Chen.
Materijalni opisGraf. prikazi.
AutorLiu, S.,Ren, Y.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisThe stability of aerobic granular sludge (AGS) is closely related to its extracellular polymeric substances (EPS). In this study, the composition and physicochemical characteristics of EPS in AGS were determined to evaluate their roles in AGS stability. The study evaluated the influence of influent phosphorus concentration on EPS protein (PN), polysaccharide (PS) and orthophosphate content, zeta potential (ζ) and fluorescence spectrum (EEM) in loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). With higher influent phosphorus concentration, the PN, PS and orthophosphate content were higher, as was the zeta potential in TB-EPS, but it had less influence on LB-EPS. Three-dimensional, synchronous fluorescence spectroscopy and fluorescence region integral (FRI) showed that protein-like substances were the primary components of LB-EPS and TB-EPS. Phosphorus had a dynamic quenching effect on EPS at a concentration between 0 mg L–1 and 17.5 mg L–1, which is the indirect production of phosphorus by cations. An increased concentration of influent phosphorus was beneficial to AGS stability.
rrep
4
NaslovPoly(3-hydroxybutyrate) production from natural gas by a methanotroph native bacterium in a bubble column bioreactor / Kianoush Khosravi-Darani, Fatemeh Yazdian, Fatemeh Babapour, A. R. Amirsadeghi.
Materijalni opisIlustr.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisReducing the total cost of poly(3-hydroxybutyrate) (PHB) production as an attractive substitute for conventional petrochemical plastics still remains an unsolved problem. The aim of this research was the screening of PHB-producing microorganisms and selection of the best suitable medium for microbial growth and PHB production from methane. A new isolated methanotroph for PHB production from natural gas was studied in different media. After selection of the suitable medium, the effect of five process variables (content of nitrogen source, disodium hydrogen phosphate, methane to air ratio, seed age, and pH) on PHB production was investigated in a bubble column bioreactor. Also, hydrodynamic and mass transfer factors (flow regime, mixing time, gas hold up, and kLa) were considered. At optimum operating conditions and engineering parameters in a bubble column, PHB content in the dried biomass reached 25 % w/w. The results showed that pH is the most important variable in the selected conditions.
rrep
5
NaslovBiocatalytic synthesis of polymeric esters used as emulsifiers / S. Ortega-Requena, M. Serrano-Arnaldos, M. C. Montiel, F. Máximo, J. Bastida, M. D. Murcia.
Materijalni opisIlustr.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisPolyglycerol polyricinoleate (PGPR) is a polymeric ester widely used as emulsifier in the food industry. In this work, PGPR biocatalytic synthesis was carried out in a onestep solvent-free enzymatic process using lipase CALB immobilized in Lewatit® Monoplus MP 64 by adsorption. The optimal immobilization conditions were determined: initial enzyme concentration of 13 mg of Lowry protein per mL phosphate buffer pH 7, and ricinoleic acid as a support activator. An immobilized derivative with 35.93 ± 4.90 mg of Lowry protein per g of dry support was obtained. It was used as a catalyst for PGPR production in open air and vacuum batch reactors, and the results obtained showed that only when the reaction equilibrium was shifted towards ester production by means of water removal, the PGPR produced fulfilled the European legislation (acid value ≤ 6 mg of KOH per g of product).
rrep
6
NaslovInfluence of sparger type and regime of fluid on biomass and lipid productivity of Chlorella vulgaris culture in a pilot airlift photobioreactor / Yaremi Lopez-Hernandez, Carlos Orozco, Ines Garcia-Peña, Jorge Ramirez-Muñoz, Luis G. Torres.
Materijalni opisIlustr.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisThe effect of different types of spargers and the influence of the air flow rate on biomass and lipids production by Chlorella vulgaris was evaluated. These data allowed correlation of the hydrodynamic behavior of the photobioreactor with the byproducts production. The hydrodynamic characterization was developed by determining the mixing time (tM), hold-up, and total volumetric mass transfer coefficient of CO2, kLa(CO2)T, at increasing air flow rates for three different spargers: star-shaped, cross-shaped and porous glass surface sparger. The hydrodynamic characterization showed that the tM decreased, while the hold-up values and the kLa(CO2)T increased as a result of the increment in the volumetric air flow rate between 5 to 17 L min–1. The highest biomass and lipid concentrations were determined at the higher aeration rate (20 L min–1), which was correlated with the lower tM, the higher hold-up and kLa(CO2)T values. Biomass and lipid production showed an inverse correlation. The highest biomass concentration (750 mg L–1) and the lowest lipid concentration (10 mg L–1) were measured with the star sparger. In contrast, when the lowest biomass concentration was obtained (240 mg L–1), the highest lipid concentration of 196 mg L–1 was measured with the glass sparger. The maximum biomass productivity values were determined at the lower aeration rate and the star sparger, with the minimum power per unit of volume, which could be useful for a cost-effective process.
rrep
7
NaslovStudy on sustainable recovery and extraction of polyhydroxyalkanoates (PHAs) produced by Cupriavidus necator using waste glycerol for medical applications / Geeta Gahlawat, Sanjeev Kumar Soni.
Materijalni opisGraf. prikazi.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisThe current study shows that Cupriavidus necator has the ability to grow on waste glycerol as carbon source, and can synthesize a highly thermostable copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Batch cultivation on waste glycerol showed accumulation of 6.76 g L–1 biomass containing 4.84 g L–1 poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer with 3-hydroxyvalerate content of 24.6 mol%. A novel recovery strategy was developed for the extraction of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer from Cupriavidus necator using recyclable solvents, i.e., propylene carbonate, butyl acetate, isoamyl alcohol, and ethyl acetate. Propylene carbonate demonstrated the recovery efficiency of 90 % and polymer purity of 95 %, at 120 °C after 30 min. Ethyl acetate exhibited a higher efficiency than butyl acetate in terms of recovering the copolymer from cells. Ethyl acetate extraction demonstrated a recovery yield of 96 % and purity of 93 % at 100 °C. Efficacy of an anionic surfactant, linear alkylbenzene sulfonic acid (LAS), was also tested for extraction, and it showed maximum yield of 84 % and purity of 90 % at 80 °C and pH 5.0. Extraction of copolymer using these solvents could help in replacing generally used chlorinated toxic solvents, such as 1,2 dichloroethane and chloroform. Further, GPC, TGA and DSC analysis revealed that the thermo-physical properties were not significantly affected by the extraction method. However, the molecular weight distribution of the polymer showed a variation depending on the type of solvent used for extraction. Subsequently, endotoxins were removed efficiently to less than 5 EU g–1 of copolymer using alkali at optimized conditions of 6 h digestion time and 2.5 N NaOH concentration for medical applications.
rrep
8
NaslovSurfactant-enhanced bioremediation of n-hexadecane-contaminated soil using halo-tolerant bacteria Paenibacillus glucanolyticus sp. strain T7-AHV isolated from marine environment / Shokouh Ghafari, Zeynab Baboli, A. Neisi, S. A. Mirzaee, Reza Darvishi Cheshmeh Soltani, Reza Saeedi, Mehrnoosh Abtahi, Sahand Jorfi.
Materijalni opisIlustr.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisA halo-tolerant bacterial strain Paenibacillus glucanolyticus sp. strain T7-AHV isolated from marine environment was used for bioremediation of n-hexadecane-contaminated soil. Soil/water ratio, initial inoculums volume, surfactant addition, n-hexadecane concentration, and salinity were investigated. The possibility of biosurfactant production by isolated strain was also studied, and the results demonstrated that it was not a biosurfactant producer, based on measurement of the surface tension of culture broth. Both tween 80 and rhamnolipid enhanced the biodegradation of n-hexadecane significantly up to 44 and 46 %, respectively. A biodegradation rate of 39.7 % was observed at salinity level of up to 2 %, and the biodegradation efficiency decreased significantly at higher salinity concentrations. A natural hydrocarbon-contaminated soil sample with total petroleum hydrocarbon (TPH) concentration of 1437 mg kg–1 was subjected to bioremediation using the selected conditions of operational parameters, and a biodegradation rate of 22.1 % was obtained.
rrep
9
NaslovAlginate lyase of a novel algae fermentation strain / Wen Zhang, X. Xia, Z. Zhang.
Materijalni opisGraf. prikazi.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisA novel algae fermentation strain was obtained in our previous work. This strain can produce alginate lyase and alcohol dehydrogenase used for the ethanol fermentation from algae. This research investigated the fermentation, separation and purification of alginate lyase, and the molecular weight of alginate lyase was determined. The optimum conditions for enzyme fermentation were as follows: fermentation medium with 20 g L–1 alginate, initial pH 6.0, and temperature 35 °C. The flasks were cultured in a shaking incubator at 120 rpm for 96 h. The enzyme was purified using the method of salting out, dialysis, and gel chromatography. After purification, the SDS-PAGE method was used to determine the molecular weight of the protein. The molecular weight of alginate lyase was 30–35 KDa. This research contributes to algae biodegradation and fuels production from algae.
rrep
10
14 (1-10)