scholarly journals Aqueous Photocatalytic Oxidation of Lignin: The Influence of Mineral Admixtures

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Elina Portjanskaja ◽  
Sergei Preis
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Oxidation ◽  
Catalyst Support ◽  
Oxidation Mechanism ◽  
Ion Concentration ◽  
Mineral Admixtures ◽  
Oh Radicals ◽  
Ferrous Ions ◽  
The Difference ◽  
The One

The photocatalytic oxidation (PCO) of UV-irradiated aqueous solutions containing lignin onTiO2was studied for the influence of ferrous ions. The addition ofFe2+, up to 2.8 mgL−1, to the acidic lignin solution leads to the drastic, for about 25%, increase in PCO efficiency. A further increase in ferrous ion concentration results in a decrease in PCO efficiency of lignin. The maximum PCO efficiency, up to 9.2 mgW−1h−1, was observed in neutral and slightly basic media: the oxidation mechanism with OH-radicals seems to prevail. Also, the difference in the PCO performance with a different attachment mode of titanium dioxide on the catalyst support was observed. Sprayed catalyst exhibited 1.5 times higher efficiency than the one attached by submersion, although sprayed one was easily resuspended in acidic lignin solutions. The efficiency of the N-doped photocatalyst active in visible light was observed to be negligible with lignin.

The Influence of Different Ph Values and High Concentrations of Na2SO4 and NaCl on the Photocatalytic Oxidation (PCO) of Methylene Blue (MB) by Aqueous Suspension of Nano-Sized TiO2

2012 ◽  
Vol 490-495 ◽  
pp. 3892-3896
Author(s):  
Yu Ping Jiang
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Oxidation ◽  
High Salinity ◽  
Aqueous Suspension ◽  
Ion Concentration ◽  
Ph Values ◽  
Orthogonal Experiments ◽  
Degradation Rates ◽  
The Difference ◽  
High Concentrations

To study the PCO of high-salinity organic wastewater, nano-sized TiO2 was used for PCO of MB in solutions with different pH values and high concentrations of Na2SO4 or NaCl. The rates of PCO were monitored by total organic carbon (TOC) measurement. The results showed that the degradation rates increased with increasing pH and decreased as the concentration of Na2SO4 or NaCl increased. The difference of degradation rates in Na2SO4 or NaCl aqueous solutions increased as the ion concentration increased. In the orthogonal experiments, the rates decreased remarkably under certain ratios of the ions concentration. The mechanisms were explored in some detail.

scholarly journals Aqueous photocatalytic oxidation of lignin and humic acids with supportedTiO2

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
Elina Portjanskaja ◽  
Sergei Preis ◽  
Juha Kallas
Keyword(s):  
Hydrogen Peroxide ◽  
Humic Acids ◽  
Photocatalytic Oxidation ◽  
Radical Formation ◽  
Ion Concentration ◽  
Alkaline Media ◽  
Radical Mechanism ◽  
Ferrous Ions ◽  
Glass Plates ◽  
Oxidation Efficiency

The photocatalytic oxidation (PCO) of UV-irradiated aqueous solutions containing humic acids and lignin was studied. The photocatalystTiO2was attached to buoyant hollow glass microspheres and glass plates. A maximum oxidation efficiency as low as1.1and2.54mgW−1h−1for humic acids and lignin, respectively, was achieved in neutral and alkaline media with 25gm−2of the buoyant catalyst. In acidic media, efficiency was even lower. The photocatalytic efficiency with the photocatalyst attached to glass plates was about 3 to 4 times higher than that for the buoyant catalyst. Ferrous ions added to acidic solutions did not increase the rate of PCO of humic acids. However the addition ofFe2+ions, up to 0.05 mM, to the lignin solution leads to a dramatic increase, about 25%, in PCO efficiency. A further increase in ferrous ion concentration results in a decrease in the PCO efficiency of lignin. Proceeding most likely by a radical mechanism, the efficiency of PCO of humic acids did not benefit from an excessive presence of hydroxyl radical promoters, such as hydrogen peroxide, although the reaction rate increased. However, PCO of lignin in the acidic medium, where OH.-radical formation is suppressed, benefited from the introduction of hydrogen peroxide due to promoted radical formation.

scholarly journals UTILIZATION OF PINEAPPLE LEATHER WASTE (ANANAS COMOCUS) AS AN OKSALATE ACID SOURCE TO IMPROVE THE EFFECTIVENESS OF Cu (II) IONALIZED ION PHOTOREDUCTION OF TiO2

2013 ◽  
Vol 1 (2) ◽  
pp. 156
Author(s):  
Husnul Hatimah ◽  
Suryati Suryati
Keyword(s):  
Oxalic Acid ◽  
Reaction System ◽  
Atomic Absorption Spectrophotometry ◽  
Ion Concentration ◽  
Process Conditions ◽  
Oh Radicals ◽  
Tio2 Photocatalysts ◽  
Aas Method ◽  
The Difference ◽  
Uv Lamp

A study has been carried out on the effect of the addition of TiO2 photocatalysts and oxalic acid sourced from pineapple skin at various pH and concentrations, to the effectiveness of Cu (II) ion photoreduction catalyzed by TiO2. The photoreduction process was carried out by irradiating the mixture consisting of a solution of Cu (II) ion and TiO2 photocatalyst powder without or in the presence of oxalic acid in a closed reactor equipped with a UV lamp with stirring. The photoreduction process conditions are 50 mL of 10 ppm Cu (II) ion solution (0.157 mmol / L) and varying concentrations of oxalic acid, and 20 mg of TiO2, with a 24-hour reaction time. The photoreduction product was determined based on the difference in the initial Cu (II) ion concentration and the remaining Cu (II) ion concentration in the solution after the photoreduction process was determined by the Atomic Absorption Spectrophotometry (AAS) method. The results showed that the addition of TiO2 could increase the effectiveness of Cu (II) ion photoreduction from 9.03% to 43.22%, which was initiated by the adsorption process. The presence of oxalic acid in pineapple skin in a photoreduction reaction system with greater concentration causes a relatively high increase in Cu (II) ion photoreduction because oxalic acid can prevent recombination of electrons with OH radicals, so that the Cu (II) photoreduction process can run optimally due to the amount of relatively large number of available electrons.

Photocatalytic oxidation mechanism of benzonitrile in aqueous suspensions of titanium dioxide

2007 ◽  
Vol 129 (1-2) ◽  
pp. 16-21 ◽  
Author(s):  
Giuseppe Marcì ◽  
Agatino Di Paola ◽  
Elisa García-López ◽  
Leonardo Palmisano
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Oxidation ◽  
Oxidation Mechanism ◽  
Aqueous Suspensions

Crystal phase-dependent generation of mobile OH radicals on TiO2: Revisiting the photocatalytic oxidation mechanism of anatase and rutile

2021 ◽  
Vol 286 ◽  
pp. 119905
Author(s):  
Ji Young Hwang ◽  
Gun-hee Moon ◽  
Bupmo Kim ◽  
Takashi Tachikawa ◽  
Tetsuro Majima ◽  
...  
Keyword(s):  
Photocatalytic Oxidation ◽  
Oxidation Mechanism ◽  
Crystal Phase ◽  
Oh Radicals

Use of a Lyophilized Reference Plasma to Compare Coagulation Test Procedures

1975 ◽  
Vol 34 (02) ◽  
pp. 426-444 ◽  
Author(s):  
J Kahan ◽  
I Nohén
Keyword(s):  
Oral Anticoagulant Therapy ◽  
Repeated Measurements ◽  
Test Procedures ◽  
Coagulation Activity ◽  
Close Relationship ◽  
Measured Activity ◽  
Test Materials ◽  
The Difference ◽  
The Stability ◽  
The One

SummaryIn 4 collaborative trials, involving a varying number of hospital laboratories in the Stockholm area, the coagulation activity of different test materials was estimated with the one-stage prothrombin tests routinely used in the laboratories, viz. Normotest, Simplastin-A and Thrombotest. The test materials included different batches of a lyophilized reference plasma, deep-frozen specimens of diluted and undiluted normal plasmas, and fresh and deep-frozen specimens from patients on long-term oral anticoagulant therapy.Although a close relationship was found between different methods, Simplastin-A gave consistently lower values than Normotest, the difference being proportional to the estimated activity. The discrepancy was of about the same magnitude on all the test materials, and was probably due to a divergence between the manufacturers’ procedures used to set “normal percentage activity”, as well as to a varying ratio of measured activity to plasma concentration. The extent of discrepancy may vary with the batch-to-batch variation of thromboplastin reagents.The close agreement between results obtained on different test materials suggests that the investigated reference plasma could be used to calibrate the examined thromboplastin reagents, and to compare the degree of hypocoagulability estimated by the examined PIVKA-insensitive thromboplastin reagents.The assigned coagulation activity of different batches of the reference plasma agreed closely with experimentally obtained values. The stability of supplied batches was satisfactory as judged from the reproducibility of repeated measurements. The variability of test procedures was approximately the same on different test materials.

The Demand For Money in Pakistan: Reply (Notes and Comments)

1975 ◽  
Vol 14 (3) ◽  
pp. 370-375
Author(s):  
M. A. Akhtar
Keyword(s):  
Interest Rates ◽  
Money Demand ◽  
Strong Support ◽  
Physical Capital ◽  
Careful Examination ◽  
Demand For Money ◽  
Weak Support ◽  
Complementarity Hypothesis ◽  
The Difference ◽  
The One

I am grateful to Abe, Fry, Min, Vongvipanond, and Yu (hereafter re¬ferred to as AFMVY) [1] for obliging me to reconsider my article [2] on the demand for money in Pakistan. Upon careful examination, I find that the AFMVY results are, in parts, misleading and that, on the whole, they add very little to those provided in my study. Nevertheless, the present exercise as well as the one by AFMVY is useful in that it furnishes us with an opportunity to view some of the fundamental problems involved in an empi¬rical analysis of the demand for money function in Pakistan. Based on their elaborate critique, AFMVY reformulate the two hypo¬theses—the substitution hypothesis and the complementarity hypothesis— underlying my study and provide us with some alternative estimates of the demand for money in Pakistan. Briefly their results, like those in my study, indicate that income and interest rates are important in deter¬mining the demand for money. However, unlike my results, they also suggest that the price variable is a highly significant determinant of the money demand function. Furthermore, while I found only a weak support for the complementarity between money demand and physical capital, the results obtained by AFMVY appear to yield a strong support for that rela¬tionship.1 The difference in results is only a natural consequence of alter¬native specifications of the theory and, therefore, I propose to devote most of this reply to the criticisms raised by AFMVY and the resulting reformulation of the two mypotheses.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

Development and Validation of Spectrophotometric and Liquid Chromatographic Methods for Estimation of Tigecycline in Injections

2020 ◽  
Vol 13 (5) ◽  
pp. 5148-5154
Author(s):  
Sagar Suman Panda ◽  
Ravi Kumar B.V.V.
Keyword(s):  
Area Under The Curve ◽  
Reversed Phase ◽  
Equal Concentration ◽  
Pharmaceutical Dosage Form ◽  
Liquid Chromatographic Method ◽  
Array Detection ◽  
The Difference ◽  
The One ◽  
Development And Validation ◽  
Liquid Chromatographic

Three new analytical methods were optimized and validated for the estimation of tigecycline (TGN) in its injection formulation. A difference UV spectroscopic, an area under the curve (AUC), and an ultrafast liquid chromatographic (UFLC) method were optimized for this purpose. The difference spectrophotometric method relied on the measurement of amplitude when equal concentration solutions of TGN in HCl are scanned against TGN in NaOH as reference. The measurements were done at 340 nm (maxima) and 410nm (minima). Further, the AUC under both the maxima and minima were measured at 335-345nm and 405-415nm, respectively. The liquid chromatographic method utilized a reversed-phase column (150mm×4.6mm, 5µm) with a mobile phase of methanol: 0.01M KH2PO4 buffer pH 3.5 (using orthophosphoric acid) in the ratio 80:20 %, v/v. The flow rate was 1.0ml/min, and diode array detection was done at 349nm. TGN eluted at 1.656min. All the methods were validated for linearity, precision, accuracy, stability, and robustness. The developed methods produced validation results within the satisfactory limits of ICH guidance. Further, these methods were applied to estimate the amount of TGN present in commercial lyophilized injection formulations, and the results were compared using the One-Way ANOVA test. Overall, the methods are rapid, simple, and reliable for routine quality control of TGN in the bulk and pharmaceutical dosage form. 

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