Displaying publications 361 - 380 of 927 in total

Abstract:
Sort:
  1. Exploring efficacy of indole-based dual inhibitors for α-glucosidase and α-amylase enzymes: In silico, biochemical and kinetic studies
    Kawde AN, Taha M, Alansari RS, Almandil NB, Anouar EH, Uddin N, et al.
    Int J Biol Macromol, 2020 Jul 01;154:217-232.
    PMID: 32173438 DOI: 10.1016/j.ijbiomac.2020.03.090
    α-Glucosidase and α-amylase are enzymes which are associated with diabetic II. These enzymes break macromolecules of sugar into monosugar molecules which is soluble in body, hence increase the sugar level in blood. There is need to develop economical and save inhibitors to prevent them from breaking sugar macromolecules to soluble molecules which will control the level of sugar in blood. Therefore, we synthesized indole-based derivatives (1-18) and evaluated as dual inhibitor for α-glucosidase and α-amylase. These chemical scaffolds were built with variation in aryl ring which were found active with good to moderate activity for α-glucosidase having IC50 value ranging from 13.99 ± 0.10 to 59.09 ± 0.30 μM when compared with standard acarbose with IC50 of 11.29 ± 0.10 μM; for α-amylase IC50 value ranging from 13.14 ± 0.10 to 58.99 ± 0.30 μM when compared with the standard acarbose with IC50 of 11.12 ± 0.10 μM. Structure activity relationship (SAR) has been established for all compounds. Enzymatic kinetic study and molecular docking study have been carried out to investigate the binding interactions α-glucosidase and α-amylase enzyme.
    Matched MeSH terms: Kinetics
  2. Fulltext Antibacterial Activity and Mode of Action of β-caryophyllene on Bacillus cereus
    Moo CL, Yang SK, Osman MA, Yuswan MH, Loh JY, Lim WM, et al.
    Pol J Microbiol, 2020;69:1-6.
    PMID: 32162852 DOI: 10.33073/pjm-2020-007
    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to -3.98 mV, compared to untreated cells (-5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to –3.98 mV, compared to untreated cells (–5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

    Matched MeSH terms: Kinetics
  3. Fulltext Purification and kinetics of the PHB depolymerase of Microbacterium paraoxydans RZS6 isolated from a dumping yard
    Sayyed RZ, Wani SJ, Alyousef AA, Alqasim A, Syed A, El-Enshasy HA
    PLoS One, 2019;14(6):e0212324.
    PMID: 31211775 DOI: 10.1371/journal.pone.0212324
    Poly-β-hydroxybutyrate (PHB) depolymerase is known to decompose PHB, biodegradable polymers and therefore has great commercial significance in the bioplastic sector. However, reports on PHB depolymerases from isolates obtained from plastic-contaminated sites that reflect the potential of the source organism is scarce. In this study, we evaluated the production of extracellular PHB depolymerase from Microbacterium paraoxydans RZS6 isolated from the plastic-contaminated site in the municipal area of Shahada, Maharashtra, India, for the first time. The isolate was identified using 16S rRNA gene sequencing, gas chromatographic analysis of fatty acid methyl esters (GC-FAME), and BIOLOG method. Ithydrolyzed PHB on minimal salt medium (MSM) containing PHB as the only source of carbon. The isolate produced PHB depolymerase at 45°C during 48 h of incubation. The enzyme was purified most efficiently using octyl-sepharose CL-4B column, with the highest purification yield of 6.675 Umg-1mL-1. The activity of the enzyme was enhanced in the presence of Ca2+ and Mg2+ ions but inhibited by Fe2+ (1 mM) ions and mercaptoethanol (1000 rpm). the nzyme kinetic analysis revealed that the enzyme was a metalloenzyme; requiring Mg2+ ions, that showed optimum enzyme activity at 30°C (mesophilic) and under neutrophilic (pH 7) conditions. Scale-up from the shake-flask level to a laboratory-scale bioreactor further enhanced the enzyme yield by 0.809 UmL-1. The molecular weight of the enzyme (40 kDa), as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, closely resembled the PHB depolymerase of Aureobacterium saperdae. Our findings highlighted the applicability of M. paraoxydans as a producer of extracellular PHB depolymerase having potential of degrading PHB under diverse conditions.
    Matched MeSH terms: Kinetics
  4. Modelling of methylene blue adsorption using peroxidase immobilized functionalized Buckypaper/polyvinyl alcohol membrane via ant colony optimization
    Jun LY, Karri RR, Mubarak NM, Yon LS, Bing CH, Khalid M, et al.
    Environ Pollut, 2020 Apr;259:113940.
    PMID: 31931415 DOI: 10.1016/j.envpol.2020.113940
    Jicama peroxidase (JP) was covalently immobilized onto functionalized multi-walled carbon nanotube (MWCNT) Buckypaper/Polyvinyl alcohol (BP/PVA) membrane and employed for degradation of methylene blue dye. The parameters of the isotherm and kinetic models are estimating using ant colony optimization (ACO), which do not meddle the non-linearity form of the respective models. The proposed inverse modelling through ACO optimization was implemented, and the parameters were evaluated to minimize the non-linear error functions. The adsorption of MB dye onto JP-immobilized BP/PVA membrane follows Freundlich isotherm model (R2 = 0.99) and the pseudo 1st order or 2nd kinetic model (R2 = 0.980 & 0.968 respectively). The model predictions from the parameters estimated by ACO resulted values close the experimental values, thus inferring that this approach captured the inherent characteristics of MB adsorption. Moreover, the thermodynamic studies indicated that the adsorption was favourable, spontaneous, and exothermic in nature. The comprehensive structural analyses have confirmed the successful binding of peroxidase onto BP/PVA membrane, as well as the effective MB dye removal using immobilized JP membrane. Compared to BP/PVA membrane, the reusability test revealed that JP-immobilized BP/PVA membrane has better dye removal performances as it can retain 64% of its dye removal efficiency even after eight consecutive cycles. Therefore, the experimental results along with modelling results demonstrated that JP-immobilized BP/PVA membrane is expected to bring notable impacts for the development of effective green and sustainable wastewater treatment technologies.
    Matched MeSH terms: Kinetics
  5. Modeling and optimization by particle swarm embedded neural network for adsorption of methylene blue by jicama peroxidase immobilized on buckypaper/polyvinyl alcohol membrane
    Jun LY, Karri RR, Yon LS, Mubarak NM, Bing CH, Mohammad K, et al.
    Environ Res, 2020 04;183:109158.
    PMID: 32044575 DOI: 10.1016/j.envres.2020.109158
    Jicama peroxidase (JP) immobilized functionalized Buckypaper/Polyvinyl alcohol (BP/PVA) membrane was synthesized and evaluated as a promising nanobiocomposite membrane for methylene blue (MB) dye removal from aqueous solution. The effects of independent process variables, including pH, agitation speed, initial concentration of hydrogen peroxide (H2O2), and contact time on dye removal efficiency were investigated systematically. Both Response Surface Methodology (RSM) and Artificial Neural Network coupled with Particle Swarm Optimization (ANN-PSO) approaches were used for predicting the optimum process parameters to achieve maximum MB dye removal efficiency. The best optimal topology for PSO embedded ANN architecture was found to be 4-6-1. This optimized network provided higher R2 values for randomized training, testing and validation data sets, which are 0.944, 0.931 and 0.946 respectively, thus confirming the efficacy of the ANN-PSO model. Compared to RSM, results confirmed that the hybrid ANN-PSO shows superior modeling capability for prediction of MB dye removal. The maximum MB dye removal efficiency of 99.5% was achieved at pH-5.77, 179 rpm, ratio of H2O2/MB dye of 73.2:1, within 229 min. Thus, this work demonstrated that JP-immobilized BP/PVA membrane is a promising and feasible alternative for treating industrial effluent.
    Matched MeSH terms: Kinetics
  6. Fulltext Kinetics Study of Microwave-Assisted Brine Extraction of Lipid from the Microalgae Nannochloropsis sp
    Zghaibi N, Omar R, Kamal SMM, Biak DRA, Harun R
    Molecules, 2020 Feb 12;25(4).
    PMID: 32059440 DOI: 10.3390/molecules25040784
    The kinetics of lipid extraction utilizing microwave-assisted extraction (MAE) from Nannochloropsis sp. microalgae were studied using a low cost and green solvent, namely brine (NaCl) solution. The kinetic modelling of the lipid extraction was performed to evaluate the mechanism of the lipid mass transfer using different extraction models, including Fick's Law, First and Second-order Rate Law and the Patricelli mathematical model. The Patricelli mathematical model described the kinetics of lipid extraction well, with the highest average values of determination coefficient (R2 ≥ 0.952) and the lowest average values of mean relative percentage deviation (MRPD ≤ 8.666%). The lipid analysis indicated a positive influence of the microwave temperature and time on the quantity and quality of extracted lipids. SEM analysis of spent microalgae clearly shows an increase in the distorted cell with increase microwave temperature and time, which could be directly correlated to the mechanism of the MAE-brine technique.
    Matched MeSH terms: Kinetics
  7. Biosorption performance of date palm empty fruit bunch wastes for toxic hexavalent chromium removal
    Rambabu K, Bharath G, Banat F, Show PL
    Environ Res, 2020 08;187:109694.
    PMID: 32485359 DOI: 10.1016/j.envres.2020.109694
    Biosorption ability of date palm empty fruit bunch (DPEFB) was examined for the removal of toxic hexavalent chromium (Cr6+) ions from synthetic wastewater. The pretreated DPEFB biosorbent was studied for its morphology and surface chemistry through Scanning electron microscopy, Energy dispersive elemental analysis and Fourier transform infrared spectroscopy. Effect of biosorption parameters such as pH, biosorbent dosage, contact time, temperature, initial feed concentration and agitation speed on the Cr6+ ions removal efficiency by DPEFB was critically evaluated. The isoelectric point for the DPEFB sorbent was observed at pH 2, above which it was dehydronated to capture the positively charged Cr6+ ions. Batch biosorption studies showed that an optimal chromium removal efficiency of 58.02% was recorded by the DPEFB biosorbent for pH 2, dosage 0.3 g, 100 rpm agitation speed, 120 min contact time, 50 mg/L initial feed concentration and 30 °C operational temperature. Thermodynamic analysis showed that the binding of Cr6+ ions on DPEFB surface was exothermic, stable and favorable at room temperature. Equilibrium behavior of chromium binding on DPEFB was more aligned to Temkin isotherm (R2 = 0.9852) highlighting the indirect interactions between Cr6+ ions and the biosorbent. Kinetic modeling revealed that the biosorption of Cr6+ ions by DPEFB obeyed pseudo-second order model than the pseudo-first order and intra-particle diffusion models. Reusability studies of the DPEFB sorbent showed that NaNO3 was an effective regenerant and the biosorbent can be efficiently reused up to three successive biosorption-desorption cycles for chromium removal. In summary, the results clearly showed that the DPEFB biowaste seems to be an efficient, economic and eco-friendly biosorbent for sustainable removal of toxic hexavalent chromium ions from domestic and industrial wastewater streams.
    Matched MeSH terms: Kinetics
  8. Fulltext Ecofriendly Approach for Treatment of Heavy-Metal-Contaminated Water Using Activated Carbon of Kernel Shell of Oil Palm
    Baby R, Hussein MZ
    Materials (Basel), 2020 Jun 09;13(11).
    PMID: 32526876 DOI: 10.3390/ma13112627
    Heavy metal ion contamination in water poses a significant risk to human health as well as to the environment. Millions of tons of agricultural wastes are produced from oil palm plantations which are challenging to manage. In this study, we converted palm kernel shells (PKS) from a palm oil plantation into activated carbon (AC) having a surface area of 1099 m2/g using phosphoric acid as an activator. The prepared material was characterized using BET, XRD, Raman, FESEM and FTIR analyses. The AC was applied for the treatment of heavy-metal-contaminated water, and different parameters; the pH, adsorbent dosage, contact time and metal ion concentrations were varied to determine the optimal conditions for the metal ion adsorption. Different kinetic models; the zeroth, first-order and second-order, and Freundlich and Langmuir isotherm models were used to determine the mechanism of metal ion adsorption by the AC. Under the optimized conditions, Cr6+ and Pb2+ were removed completely, while Zn2+ and Cd2+ were more than 80% removed. This is a greener approach in which an agricultural waste, PKS is converted into a useful product, activated carbon and subsequently applied for the treatment of heavy metal-contaminated water.
    Matched MeSH terms: Kinetics
  9. Fulltext Optimization of Washing Processes in Solvothermal Synthesis of Nickel-Based MOF-74
    Kamal K, Bustam MA, Ismail M, Grekov D, Mohd Shariff A, Pré P
    Materials (Basel), 2020 Jun 17;13(12).
    PMID: 32560394 DOI: 10.3390/ma13122741
    Solvothermal synthesis is the most preferable preparation technique of metal-organic frameworks (MOFs) that consists of reactants mixing, ultrasonication, solvothermal reaction, product washing, and solvent evacuation. Owing to fast reaction kinetics in solvothermal reaction, this technique allows for production of uniform MOF particles with high crystallinity, high phase purity, and small particle sizes. However, it exhibits some difficulties of washing processes that may involve the blockage of pores due to incomplete removal of reactive medium from MOF products. The present study proposes an improvement of washing processes by introducing centrifugal separations with optimized parameters at two different stages: after reaction and after product washing. Nickel‑based MOF‑74 was synthesized as the experimental material for this purpose. The quality of the produced sample was evaluated by gas adsorption performance using CO2 at 1 bar and 25 °C. The final sample of the optimized synthesis routes was able to adsorb 5.80 mmol/g of CO2 uptake, which was competitive with literature data and significantly higher than the sample of the basic synthesis. Fourier‑transform infrared spectroscopy (FTIR) and powder X‑ray diffraction (PXRD) analysis revealed that the sample displayed much higher crystallinity structure and was clean from impurities after centrifugations. The outcome indicated the success of separation between MOF products and reactive medium during washing processes, leading to the effective pore activation of MOFs.
    Matched MeSH terms: Kinetics
  10. Characterisation, in-vitro and in-vivo evaluation of valproic acid-loaded nanoemulsion for improved brain bioavailability
    Tan SF, Kirby BP, Stanslas J, Basri HB
    J Pharm Pharmacol, 2017 Nov;69(11):1447-1457.
    PMID: 28809443 DOI: 10.1111/jphp.12800
    OBJECTIVE: This study was aimed to investigate the potential of formulated valproic acid-encapsulated nanoemulsion (VANE) to improve the brain bioavailability of valproic acid (VPA).

    METHODS: Valproic acid-encapsulated nanoemulsions were formulated and physically characterised (osmolarity, viscosity, drug content, drug encapsulation efficiency). Further investigations were also conducted to estimate the drug release, cytotoxic profile, in-vitro blood-brain barrier (BBB) permeability, pharmacokinetic parameter and the concentration of VPA and VANE in blood and brain.

    KEY FINDINGS: Physical characterisation confirmed that VANE was suitable for parenteral administration. Formulating VPA into nanoemulsion significantly reduced the cytotoxicity of VPA. In-vitro drug permeation suggested that VANEs crossed the BBB as freely as VPA. Pharmacokinetic parameters of VANE-treated rats in plasma and brain showed F3 VANE had a remarkable improvement in AUC, prolongation of half-life and reduction in clearance compared to VPA. Given the same extent of in-vitro BBB permeation of VPA and VANE, the higher bioavailability of VANE in brain was believed to have due to higher concentration of VANE in blood. The brain bioavailability of VPA was improved by prolonging the half-life of VPA by encapsulating it within the nanoemulsion-T80.

    CONCLUSIONS: Nanoemulsion containing VPA has alleviated the cytotoxic effect of VPA and improved the plasma and brain bioavailability for parenteral delivery of VPA.

    Matched MeSH terms: Kinetics
  11. Congo red dye removal from aqueous environment by cationic surfactant modified-biomass derived carbon: Equilibrium, kinetic, and thermodynamic modeling, and forecasting via artificial neural network approach
    Karaman C, Karaman O, Show PL, Karimi-Maleh H, Zare N
    Chemosphere, 2022 Mar;290:133346.
    PMID: 34929270 DOI: 10.1016/j.chemosphere.2021.133346
    Herein, it was aimed to optimize, model, and forecast the biosorption of Congo Red onto biomass-derived biosorbent. Therefore, the waste-orange-peels were processed to fabricate biomass-derived carbon, which was activated by ZnCl2 and modified with cetyltrimethylammonium bromide. The physicochemical properties of the biosorbents were explored by scanning electron microscopy and N2 adsorption/desorption isotherms. The effects of pH, initial dye concentration, temperature, and contact duration on the biosorption capacity were investigated and optimized by batch experimental process, followed by the kinetics, equilibrium, and thermodynamics of biosorption were modeled. Furthermore, various artificial neural network (ANN) architectures were applied to experimental data to optimize the ANN model. The kinetic modeling of the biosorption offered that biosorption was in accordance both with the pseudo-second-order and saturation-type kinetic model, and the monolayer biosorption capacity was calculated as 666.67 mg g-1 at 25 °C according to Langmuir isotherm model. According to equilibrium modeling, the Freundlich isotherm model was better fitted to the experimental data than the Langmuir isotherm model. Moreover, the thermodynamic modeling revealed biosorption took place spontaneously as an exothermic process. The findings revealed that the best ANN architecture trained with trainlm as the backpropagation algorithm, with tansig-purelin transfer functions, and 14 neurons in the single hidden layer with the highest coefficient of determination (R2 = 0.9996) and the lowest mean-squared-error (MSE = 0.0002). The well-agreement between the experimental and ANN-forecasted data demonstrated that the optimized ANN model can predict the behavior of the anionic dye biosorption onto biomass-derived modified carbon materials under various operation conditions.
    Matched MeSH terms: Kinetics
  12. Multistage optimizations of slow pyrolysis synthesis of biochar from palm oil sludge for adsorption of lead
    Lee XJ, Lee LY, Hiew BYZ, Gan S, Thangalazhy-Gopakumar S, Kiat Ng H
    Bioresour Technol, 2017 Dec;245(Pt A):944-953.
    PMID: 28946195 DOI: 10.1016/j.biortech.2017.08.175
    This research investigated the removal of lead (Pb(2+)) by a novel biochar derived from palm oil sludge (POS-char) by slow pyrolysis. Multistage optimizations with central composite design were carried out to firstly optimize pyrolysis parameters to produce the best POS-char for Pb(2+) removal and secondly to optimize adsorption conditions for the highest removal of Pb(2+). The optimum pyrolysis parameters were nitrogen flowrateof30mLmin(-1), heating rateof10°Cmin(-1), temperatureof500°C and timeof30min. The optimum Pb(2+) adsorption conditions were concentrationof200mgL(-1), timeof60min, dosageof0.3g and pH of 3.02. The various functional groups within POS-char played a vital role in Pb(2+) uptake. Regeneration was demonstrated to be feasible using hydrochloric acid. Adsorption equilibrium was best described by Freundlich model. At low concentration range, adsorption kinetic obeyed pseudo-first-order model, but at high concentration range, it followed pseudo-second-order model. Overall, the results highlighted that POS-char is an effective adsorbent for Pb(2+) removal.
    Matched MeSH terms: Kinetics
  13. Fulltext Base Catalytic Approach: A Promising Technique for the Activation of Biochar for Equilibrium Sorption Studies of Copper, Cu(II) Ions in Single Solute System
    Hamid SBA, Chowdhury ZZ, Zain SM
    Materials (Basel), 2014 Apr 09;7(4):2815-2832.
    PMID: 28788595 DOI: 10.3390/ma7042815
    This study examines the feasibility of catalytically pretreated biochar derived from the dried exocarp or fruit peel of mangostene with Group I alkali metal hydroxide (KOH). The pretreated char was activated in the presence of carbon dioxide gas flow at high temperature to upgrade its physiochemical properties for the removal of copper, Cu(II) cations in single solute system. The effect of three independent variables, including temperature, agitation time and concentration, on sorption performance were carried out. Reaction kinetics parameters were determined by using linear regression analysis of the pseudo first, pseudo second, Elovich and intra-particle diffusion models. The regression co-efficient, R² values were best for the pseudo second order kinetic model for all the concentration ranges under investigation. This implied that Cu(II) cations were adsorbed mainly by chemical interactions with the surface active sites of the activated biochar. Langmuir, Freundlich and Temkin isotherm models were used to interpret the equilibrium data at different temperature. Thermodynamic studies revealed that the sorption process was spontaneous and endothermic. The surface area of the activated sample was 367.10 m²/g, whereas before base activation, it was only 1.22 m²/g. The results elucidated that the base pretreatment was efficient enough to yield porous carbon with an enlarged surface area, which can successfully eliminate Cu(II) cations from waste water.
    Matched MeSH terms: Kinetics
  14. Fulltext Inhibition of Mild Steel Corrosion in Sulfuric Acid Solution by New Schiff Base
    Al-Amiery AA, Kadhum AAH, Kadihum A, Mohamad AB, How CK, Junaedi S
    Materials (Basel), 2014 Jan 28;7(2):787-804.
    PMID: 28788488 DOI: 10.3390/ma7020787
    The efficiency of Schiff base derived from 4-aminoantipyrine, namely 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene) hydrazinecarbothioamide as a corrosion inhibitor on mild steel in 1.0 M H2SO4 was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PD) and electrochemical frequently modulation (EFM) in addition to the adsorption isotherm, corrosion kinetic parameters and scanning electron microscopy (SEM). The results showed that this inhibitor behaved as a good corrosion inhibitor, even at low concentration, with a mean efficiency of 93% and, also, a reduction of the inhibition efficiency as the solution temperature increases. A polarization technique and EIS were tested for different concentrations and different temperatures to reveal that this compound is adsorbed on the mild steel, therefore blocking the active sites, and the adsorption follows the Langmuir adsorption isotherm model. The excellent inhibition effectiveness of 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene)hydrazinecarbothioamide was also verified by scanning electron microscope (SEM).
    Matched MeSH terms: Kinetics
  15. Fulltext Carbon Derived from Jatropha Seed Hull as a Potential Green Adsorbent for Cadmium (II) Removal from Wastewater
    Mohammad M, Yaakob Z, Abdullah SRS
    Materials (Basel), 2013 Oct 09;6(10):4462-4478.
    PMID: 28788340 DOI: 10.3390/ma6104462
    Carbon from jatropha seed hull (JC) was prepared to study the adsorption of cadmium ions (Cd(2+)) from aqueous solutions under various experimental conditions. Batch equilibrium methods have been used to study the influences of the initial metal ion concentration (0.5-50 ppm), dosage (0.2-1 g), contact time (0-300 min), pH (2-7), and temperature (26-60 °C) on adsorption behavior. It has been found that the amount of cadmium adsorbed increases with the initial metal ion concentration, temperature, pH, contact time, and amount of adsorbent. A kinetic study proved that the mechanism of Cd(2+) adsorption on JC followed a three steps process, confirmed by an intraparticle diffusion model: rapid adsorption of metal ions, a transition phase, and nearly flat plateau section. The experimental results also showed that the Cd(2+) adsorption process followed pseudo-second-order kinetics. The Langmuir and Freundlich adsorption isotherm models were used to describe the experimental data, with the former exhibiting a better correlation coefficient than the latter (R² = 0.999). The monolayer adsorption capacity of JC has been compared with the capacities of the other reported agriculturally-based adsorbents. It has been clearly demonstrated that this agricultural waste generated by the biofuel industry can be considered a potential low-cost adsorbent for the removal of Cd(2+) from industrial effluents.
    Matched MeSH terms: Kinetics
  16. Fulltext Electrochemical Study on Newly Synthesized Chlorocurcumin as an Inhibitor for Mild Steel Corrosion in Hydrochloric Acid
    Al-Amiery AA, Kadhum AAH, Mohamad AB, Musa AY, Li CJ
    Materials (Basel), 2013 Nov 27;6(12):5466-5477.
    PMID: 28788402 DOI: 10.3390/ma6125466
    A new curcumin derivative, i.e., (1E,4Z,6E)-5-chloro-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,4,6-trien-3-one (chlorocurcumin), was prepared starting with the natural compound curcumin. The newly synthesized compound was characterized by elemental analysis and spectral studies (IR, ¹H-NMR and 13C-NMR). The corrosion inhibition of mild steel in 1 M HCl by chlorocurcumin has been studied using potentiodynamic polarization (PDP) measurements and electrochemical impedance spectroscopy (EIS). The inhibition efficiency increases with the concentration of the inhibitor but decreases with increases in temperature. The potentiodynamic polarization reveals that chlorocurcumin is a mixed-type inhibitor. The kinetic parameters for mild steel corrosion were determined and discussed.
    Matched MeSH terms: Kinetics
  17. Assessment of fish scales waste as a low cost and eco-friendly adsorbent for removal of an azo dye: Equilibrium, kinetic and thermodynamic studies
    Ooi J, Lee LY, Hiew BYZ, Thangalazhy-Gopakumar S, Lim SS, Gan S
    Bioresour Technol, 2017 Dec;245(Pt A):656-664.
    PMID: 28917100 DOI: 10.1016/j.biortech.2017.08.153
    In this study, AB113 dye was successfully sequestered using a novel adsorbent made of mixed fish scales (MFS). The influence of adsorbent dosage, initial pH, temperature, initial concentration and contact time on the adsorption performance was investigated. The surface chemistry and morphology of the adsorbent were examined by FTIR, TGA and SEM. Amides, phosphate and carbonate groups were evidently responsible for the high affinity of MFS towards the dye. The adsorption equilibrium and kinetic were well described by Langmuir and pseudo-second-order models, respectively. The maximum adsorption capacities of MFS were 145.3-157.3mg/g at 30-50°C. The adsorption of AB113 dye onto the adsorbent was exothermic and spontaneous as reflected by the negative enthalpy and Gibbs energy changes. The results support MFS asa potential adsorbent for AB113 dye removal.
    Matched MeSH terms: Kinetics
  18. Adsorption of divalent heavy metal ion by mesoporous-high surface area chitosan/poly (ethylene oxide) nanofibrous membrane
    Shariful MI, Sharif SB, Lee JJL, Habiba U, Ang BC, Amalina MA
    Carbohydr Polym, 2017 Feb 10;157:57-64.
    PMID: 27987964 DOI: 10.1016/j.carbpol.2016.09.063
    In this study, chitosan/poly (ethylene oxide) nanofibres were fabricated at different chitosan:PEO weight ratio by electrospinning process. The effects of chitosan/PEO composition onto adsorption capability for Cu(II), Zn(II) and Pb(II) ions were studied. Formation of beadless fibres were achieved at 60:40 chitosan:PEO ratio. Average fiber diameter, maximum tensile strength and the specific surface area of the beadless fibres were found to be 115±31nm, 1.58MPa and 218m2/g, respectively. Chitosan/PEO composition that produced beadless fibres tend to possess higher hydrophilicity and maximum specific surface area. These characteristics lead the beadless fibres to the maximum adsorption capability. Adsorption equilibrium data were analysed by Langmuir and Freundlich isotherm. Freundlich isotherm showed the better fit with the experimental data and proved the existence of the monolayer adsorption conditions. The maximum adsorption capacity of the beadless fibres for Cu(II), Zn(II) and Pb(II) ions were found to be 120, 117 and 108mgg-1, respectively.
    Matched MeSH terms: Kinetics
  19. Hyaluronic acid-modified betamethasone encapsulated polymeric nanoparticles: fabrication, characterisation, in vitro release kinetics, and dermal targeting
    Pandey M, Choudhury H, Gunasegaran TAP, Nathan SS, Md S, Gorain B, et al.
    Drug Deliv Transl Res, 2019 04;9(2):520-533.
    PMID: 29488170 DOI: 10.1007/s13346-018-0480-1
    Atopic dermatitis (AD) is a chronically relapsing eczematous skin disease characterised by frequent episodes of rashes, severe flares, and inflammation. Till date, there is no absolute therapy for the treatment of AD; however, topical corticosteroids (TCs) are the majorly prescribed class of drugs for the management of AD in both adults and children. Though, topical route is most preferable; however, limited penetration of therapeutics across the startum cornum (SC) is one of the major challenges for scientists. Therefore, the present study was attempted to fabricate a moderate-potency TC, betamethasone valerate (BMV), in the form of chitosan nanoparticles (CS-NPs) for optimum dermal targeting and improved penetration across the SC. To further improve the targeting efficiency of BMV and to potentiate its therapeutic efficacy, the fabricated BMV-CS-NPs were coated with hyaluronic acid (HA). The prepared NPs were characterised for particle size, zeta potential, polydispersity index (PDI), entrapment efficiency, loading capacity, crystallinity, thermal behaviour, morphology, in vitro release kinetics, drug permeation across the SC, and percentage of drug retained into various skin layers. Results showed that optimised HA-BMV-CS-NPs exhibited optimum physicochemical characteristics including finest particle size (
    Matched MeSH terms: Kinetics
  20. Fulltext Silver Nanoparticles in the Water Environment in Malaysia: Inspection, characterization, removal, modeling, and future perspective
    Syafiuddin A, Salmiati S, Hadibarata T, Kueh ABH, Salim MR, Zaini MAA
    Sci Rep, 2018 01 17;8(1):986.
    PMID: 29343711 DOI: 10.1038/s41598-018-19375-1
    The current status of silver nanoparticles (AgNPs) in the water environment in Malaysia was examined and reported. For inspection, two rivers and two sewage treatment plants (STPs) were selected. Two activated carbons derived from oil palm (ACfOPS) and coconut (ACfCS) shells were proposed as the adsorbent to remove AgNPs. It was found that the concentrations of AgNPs in the rivers and STPs are in the ranges of 0.13 to 10.16 mg L-1 and 0.13 to 20.02 mg L-1, respectively, with the highest concentration measured in July. ACfOPS and ACfCS removed up to 99.6 and 99.9% of AgNPs, respectively, from the water. The interaction mechanism between AgNPs and the activated carbon surface employed in this work was mainly the electrostatic force interaction via binding Ag+ with O- presented in the activated carbon to form AgO. Fifteen kinetic models were compared statistically to describe the removal of AgNPs. It was found that the experimental adsorption data can be best described using the mixed 1,2-order model. Therefore, this model has the potential to be a candidate for a general model to describe AgNPs adsorption using numerous materials, its validation of which has been confirmed with other material data from previous works.
    Matched MeSH terms: Kinetics
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links