scholarly journals Kinetic modeling of oxidation parameters and activities of lipase-lipoxygenase in wheat germ oil

2021 ◽  
Vol 72 (3) ◽  
pp. e423
Author(s):  
Y. Erim Köse

This study aimed to investigate the oxidation profile of wheat germ oil extracted from raw germ during the stabilization with microwave (MW) treatment, and the kinetics of the oxidation parameters (free fatty acids (FFA), peroxide value (PV), thiobarbituric acid (TBA), α-tocopherol, lipase (LA) and lipoxygenase (LOX) enzymes activities) under different storage conditions. For stabilizing raw germ, the MW was treated at 700 W for three minutes. The oxidation parameters for the kinetic modeling were analyzed at different storage times (0, 15, 30, 45, 60,75, 90, and 105. days) and storage temperatures (-18, 0, 4, and 25 °C). The parameters were mathematically modelled and the PV and LA fitted well to the zero-order kinetic model, while FFA with α-tocopherol and TBA followed the first and second-order kinetics, respectively. The kinetic constant (k) was described by an Arrhenius equation and the activation energy ranged from 5.72 to 18.5 kJ/mol for the stabilized germ.

2013 ◽  
Vol 12 (2) ◽  
pp. 175-180 ◽  

An Upflow Anaerobic Sludge Bed (UASB) reactor was used to evaluate mesophilic anaerobic treatment of a pre-acidified fruit wastewater. The system was operated at increasing volumetric loading rates by sequentially increasing wastewater flowrate. The operational temperature was maintained initially at 37 oC and consequently decreased to 30 and 25 oC. For the volumetric loading rates examined i.e. 5-35 KgCOD m-3d-1), the UASB attained COD removal levels higher than 70%. The first-order kinetics were found to be suitable for representation of the substrate removal. The kinetic constant decreased from 23 to 21 and 19 d-1 at 37, 30 and 25 oC respectively. Prediction of effluent COD and methane production rate during continuous reactor operation was possible using the first-order kinetic model.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Barbara Klik ◽  
Zygmunt M. Gusiatin ◽  
Dorota Kulikowska

AbstractThis paper presents the first tests of Cu (7875 mg/kg), Pb (1414 mg/kg) and Zn (566 mg/kg) removal from contaminated soil with sewage-sludge–derived washing agents (SS_WAs) (dissolved organic matter, DOM; soluble humic-like substances, HLS; soluble humic substances, SHS) and Na2EDTA (as a standard benchmark) in column experiments. Flow rates of 0.5 ml/min and 1 ml/min were used. Using a 1. order kinetic model, the kinetic constant (k), the maximum concentrations of each metal removed (Cmax), and the initial rates of metal removal (r) were established. At both flow rates, stable flow velocity was maintained for approximately eight pore volumes, for flushing times of 8 h (1.0 ml/min) and 16 h (0.5 ml/min). Although the flow rate did not influence k, it influenced Cmax: at 1 ml/min, Cmax values were higher than at 0.5 ml/min. For Cu and Zn, but not Pb, k was about twofold higher with Na2EDTA than with SS_WAs. Although Na2EDTA gave the highest kCu, Cmax,Cu was highest with DOM (Na2EDTA, 66%; DOM 73%). For Pb removal, HLS was the most effective SS_WA (77%; Na2EDTA was 80% effective). kZn was about twofold higher with Na2EDTA than with SS_WAs. Cmax,Zn was highest with HLS. The quick mobilization of Cu, Pb and Zn with most of the WAs corresponded to efficient metal removal from the exchangeable (F1) fraction.


Author(s):  
Lieke Riadi ◽  
Theresia Desy Askitosari ◽  
Ragil Puspita Dutaning Widhi ◽  
Melvina Laurensia ◽  
Yuana Elly Agustin ◽  
...  

Abstract The microalga Arthrospira platensis (Spirulina) is used for tempeh wastewater treatment. The microalga growth and the kinetics of COD degradation under different light intensities (2,100 and 4,300 lux), tempeh wastewater concentrations (0, 0.5, 1, 1.5% v/v), and sodium nitrate concentrations (0, 0.75, 1, 2, 2.5 g/L) were studied. Improved cell growth in wastewater indicated that mixotrophic growth was preferred. The addition of sodium nitrate up to 2 g/L increased the COD removal. The highest COD removal was 92.2%. It was obtained from the cultivation with 1% v/v tempeh wastewater, 2 g/L sodium nitrate, 2,100 lux, and the specific growth rate of 0.33 ± 0.01 day−1. The COD removal followed a pseudo first – order kinetic model with the kinetic constant of 0.3748 day−1 and the nitrate uptake rate of 0.122 g/L-day. The results can be used to design a pilot – scale tempeh wastewater treatment facility using A. platensis for tertiary treatment. Based on the kinetic model, a 20 m3 reactor can treat tempeh wastewater to reduce the COD from 400 to 100 ppm in 4 days and produces approximately 32.8 kg of dried microalgae.


Author(s):  
Hadeer Zakaria ◽  
Tarek M. Mostafa ◽  
Gamal A. El-Azab ◽  
Nagy AH Sayed-Ahmed

Abstract. Background: Elevated homocysteine levels and malnutrition are frequently detected in hemodialysis patients and are believed to exacerbate cardiovascular comorbidities. Omega-3 fatty acids have been postulated to lower homocysteine levels by up-regulating metabolic enzymes and improving substrate availability for homocysteine degradation. Additionally, it has been suggested that prevention of folate depletion by vitamin E consumption decreases homocysteine levels. However, data on the effect of omega-3 fatty acids and/or vitamin E on homocysteine levels and nutritional status have been inconclusive. Therefore, this study was planned to examine the effect of combined supplementation of fish oil, as a source of omega-3 fatty acids, with wheat germ oil, as a source of vitamin E, on homocysteine and nutritional indices in hemodialysis patients. Methods: This study was a randomized, double-blind, placebo-controlled trial. Forty-six hemodialysis patients were randomly assigned to two equally-sized groups; a supplemented group who received 3000 mg/day of fish oil [1053 mg omega-3 fatty acids] plus 300 mg/day of wheat germ oil [0.765 mg vitamin E], and a matched placebo group who received placebo capsules for 4 months. Serum homocysteine and different nutritional indices were measured before and after the intervention. Results: Twenty patients in each group completed the study. At the end of the study, there were no significant changes in homocysteine levels and in the nutritional indices neither in the supplemented nor in the placebo-control groups (p > 0.05). Conclusions: Fish oil and wheat germ oil combination did not produce significant effects on serum homocysteine levels and nutritional indices of hemodialysis patients.


2018 ◽  
Vol 69 (9) ◽  
pp. 2323-2330 ◽  
Author(s):  
Daniela C. Culita ◽  
Claudia Maria Simonescu ◽  
Rodica Elena Patescu ◽  
Nicolae Stanica

A series of three chitosan-based magnetic composites was prepared through a simple coprecipitation method. It was investigated the influence of mass ratio between chitosan and magnetite on the physical and chemical properties of the composites in order to establish the optimum conditions for obtaining a composite with good adsorption capacity for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions. It was found that the microspheres prepared using mass ratio chitosan / magnetite 1.25/1, having a saturation magnetization of 15 emu g--1, are the best to be used as adsorbent for the metal ions. The influence of different parameters such as initial pH values, contact time, initial concentration of metal ions, on the adsorption of Pb(II) and Cu(II) onto the chitosan-based magnetic adsorbent was investigated in details. The adsorption process fits the pseudo-second-order kinetic model in both mono and bicomponent systems, and the maximum adsorption capacities calculated on the basis of the Langmuir model were 79.4 mg g--1 for Pb(II) and 48.5 mg g--1 for Cu(II) in monocomponent systems, while in bicomponent systems were 88.3 and 49.5 mg g--1, respectively. The results revealed that the as prepared chitosan-based magnetic adsorbent can be an effective and promising adsorbent for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions.


2002 ◽  
Vol 2 (5-6) ◽  
pp. 217-224 ◽  
Author(s):  
Z. Reddad ◽  
C. Gérente ◽  
Y. Andrès ◽  
P. Le Cloirec

In the present work, sugar beet pulp, a common waste from the sugar refining industry, was studied in the removal of metal ions from aqueous solutions. The ability of this cheap biopolymer to sorb several metals namely Pb2+, Cu2+, Zn2+, Cd2+ and Ni2+ in aqueous solutions was investigated. The metal fixation capacities of the sorbent were determined according to operating conditions and the fixation mechanisms were identified. The biopolymer has shown high elimination rates and interesting metal fixation capacities. A pseudo-second-order kinetic model was tested to investigate the adsorption mechanisms. The kinetic parameters of the model were calculated and discussed. For 8 × 10-4 M initial metal concentration, the initial sorption rates (v0) ranged from 0.063 mmol.g-1.min-1 for Pb2+ to 0.275 mmol.g-1.min-1 for Ni2+ ions, with the order: Ni2+ > Cd2+ > Zn2+ > Cu2+ > Pb2+. The equilibrium data fitted well with the Langmuir model and showed the following affinity order of the material: Pb2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+. Then, the kinetic and equilibrium parameters calculated qm and v0 were tentatively correlated to the properties of the metals. Finally, equilibrium experiments in multimetallic systems were performed to study the competition of the fixation of Pb2+, Zn2+ and Ni2+ cations. In all cases, the metal fixation onto the biopolymer was found to be favourable in multicomponent systems. Based on these results, it is demonstrated that this biosorbent represents a low-cost solution for the treatment of metal-polluted wastewaters.


2018 ◽  
Vol 21 (8) ◽  
pp. 583-593 ◽  
Author(s):  
Sara Rahnama ◽  
Shahab Shariati ◽  
Faten Divsar

Objective: In this research, a novel magnetite titanium dioxide nanocomposite functionalized by amine groups (Fe3O4@SiO2@TiO2-NH2) was synthesized and its ability for efficient removal of Acid Fuchsine as an anionic dye from aqueous solutions was investigated. Method: The core-shell structure of Fe3O4@SiO2@TiO2 was prepared using Fe3O4 as magnetic core, tetra ethyl orthosilicate as silica and tetra butyl titanate as titanium source for shell. The synthesized nanocomposites (particle size lower than 44 nm) were characterized by FT-IR, XRD, DRS, SEM and TGA instruments. The various experimental parameters affecting dye removal efficiency were investigated and optimized using Taguchi fractional factorial design. Results: The synthesized adsorbent showed the highest removal efficiency of Acid Fuchsine (99 %) at pH= 3.5, without salt addition and during stirring at contact times less than 10 minutes. The study of kinetic models at two concentration levels showed the fast dye sorption on the surface of proposed nanocomposites with pseudo second order kinetic model (R2=1). Also, the fitting of Acid Fuchsine sorption data to Freundlich, Langmuir and Temkin isotherms suggested that Freundlich model gave a better fitting than other models (R2=0.9936, n=2). Conclusion: Good chemical stability, excellent magnetic properties, very fast adsorption kinetics and high removal efficiency make the synthesized nanocomposite as a proper recoverable sorbent for removal of Acid Fuchsine dye from wastewaters.


2021 ◽  
Author(s):  
Anam Khalid ◽  
Muhammad Sohaib ◽  
Muhammad Tahir Nadeem ◽  
Farhan Saeed ◽  
Ali Imran ◽  
...  

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1615
Author(s):  
Thanh Tam Nguyen ◽  
Hung-Hsiang Chen ◽  
Thi Hien To ◽  
Yu-Chen Chang ◽  
Cheng-Kuo Tsai ◽  
...  

Adsorbent made by carbonization of biomass under oxygen-limited conditions has become a promising material for wastewater treatment owing to its cost-effective, simple, and eco-friendly processing method. Ultrasound is considered a green technique to modify carbon materials because it uses water as the solvent. In this study, a comparison of Reactive Black 5 (RB5) adsorption capacity between biochar (BC) generated by pyrolysis of water bamboo (Zizania latifolia) husks at 600 °C and ultrasound-assisted biochar (UBC) produced by pyrolysis at 600 °C assisted by ultrasonic irradiation was performed. UBC showed a greater reaction rate and reached about 80% removal efficiency after 4 h, while it took 24 h for BC to reach that level. Scanning electron microscope (SEM) images indicated that the UBC morphology surface was more porous, with the structure of the combination of denser mesopores enhancing physiochemical properties of UBC. By Brunauer, Emmett, and Teller (BET), the specific surface areas of adsorbent materials were analyzed, and the surface areas of BC and UBC were 56.296 m2/g and 141.213 m2/g, respectively. Moreover, the pore volume of UBC was 0.039 cm3/g, which was higher than that of BC at 0.013 cm3/g. The adsorption isotherms and kinetics revealed the better fits of reactions to Langmuir isotherm and pseudo-second-order kinetic model, indicating the inclination towards monolayer adsorption and chemisorption of RB5 on water bamboo husk-based UBC.


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