scholarly journals SINTESIS DAN KARAKTERISASI SILIKA GEL DARI LIMBAH KACA SERTA APLIKASINYA PADA KROMATOGRAFI KOLOM

2018 ◽  
Vol 1 (1) ◽  
pp. 10
Author(s):  
Verry Andre Fabiani

Silica gel synthesis from glass waste have been carried out with activation and purification method by using hydrochloride acid. Hydrochloride acid were varied 8 N, 10 N, and 12 N to observe optimum concentration in purification of silica gel and component separation in chromatography column. Gravimetric analysis result showed 12 N hydrochloride acid produce ~100 % silica. XRD and FTIR analysis revealed that synthetic gel silica was amorphous where its IR absorption bands were at 3426 cm-1, 1620 cm-1, 1080 cm-1, 772 cm-1 and 478 cm-1. The absorption bands agreed to standard gel silica and spectrum. The most effective HCl in gel silica synthesis was 12 N, caused by its ability to separate color component in a column. The synthetic silica that can be applied as stationary phase in column chromatography.

2019 ◽  
Vol 9 (3) ◽  
pp. 240-247
Author(s):  
Prabhakar Panzade ◽  
Priyanka Somani ◽  
Pavan Rathi

Background and Objective: The top approach to deliver poorly soluble drugs is the use of a highly soluble form. The present study was conducted to enhance the solubility and dissolution of a poorly aqueous soluble drug nevirapine via a pharmaceutical cocrystal. Another objective of the study was to check the potential of the nevirapine cocrystal in the dosage form. Methods: A neat and liquid assisted grinding method was employed to prepare nevirapine cocrystals in a 1:1 and 1:2 stoichiometric ratio of drug:coformer by screening various coformers. The prepared cocrystals were preliminary investigated for melting point and saturation solubility. The selected cocrystal was further confirmed by Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC), and Xray Powder Diffraction (XRPD). Further, the cocrystal was subjected to in vitro dissolution study and formulation development. Results: The cocrystal of Nevirapine (NVP) with Para-Amino Benzoic Acid (PABA) coformer prepared by neat grinding in 1:2 ratio exhibited greater solubility. The shifts in IR absorption bands, alterations in DSC thermogram, and distinct XRPD pattern showed the formation of the NVP-PABA cocrystal. Dissolution of NVP-PABA cocrystal enhanced by 38% in 0.1N HCl. Immediate release tablets of NVP-PABA cocrystal exhibited better drug release and less disintegration time. Conclusion: A remarkable increase in the solubility and dissolution of NVP was obtained through the cocrystal with PABA. The cocrystal also showed great potential in the dosage form which may provide future direction for other drugs.


2020 ◽  
Vol 128 (8) ◽  
pp. 1077
Author(s):  
В.П. Булычев ◽  
М.В. Бутурлимова ◽  
К.Г. Тохадзе

The frequencies and intensities of IR absorption bands of symmetric and asymmetric H-bonded complexes [FL1FL2F]- (L1, L2 = K-meson Ka, proton H, deuton D, and triton T) are calculated. The equilibrium configuration and potential energy and dipole moment surfaces of isotopologues [FL1FL2F]- were calculated by the MP2/6-311++G(3df,3pd) method with the basis set superposition error taken into account. The calculations of spectral parameters with allowance for anharmonic interactions of all vibrations were carried out using the second-order vibrational perturbation theory. Variation of Li and L2 masses in wide regions allowed significant changes in the forms of normal vibrations and values of anharmonic interaction constants upon isotopic substitution to be obtained. The trends in the changes of spectral parameters were determined upon transition from one symmetric isotopologue to another and upon transition from symmetric to asymmetric isotopologues. The D-F stretching band frequency predicted for [FHFDF]- is in good agreement with the experimental value. The assignment of this band was improved.


Author(s):  
E. A. Tolkacheva ◽  
V. P. Markevich ◽  
L. I. Murin

The isotopic content of natural silicon (28Si (92.23 %), 29Si (4.68 %) и 30Si (3.09 %)) affects noticeably the shape of IR absorption bands related to the oxygen impurity atoms. In the present work an attempt is undertaken to determine the positions of local vibrational modes (LVMs), related to quasimolecules 28Si16OS29Si and 28Si16OS30Si (OS – substitutional oxygen atom), for the absorption spectra measured at room temperature. An estimation of the isotopic shifts of corresponding modes is done by fitting the shape of the experimentally measured absorption band related to the vacancy–oxygen center in irradiated Si crystals. The LVM isotope shifts are found to be equal 2,2 ± 0.25 cm–1 for 28Si-16OS29Si and 4,3 ± 0,9 см–1 for 28Si-16OS30Si in relation to the basic band due to 28Si-16OS28Si, and the full width at half maximum of the A-center absorption band (28Si-16OS28Si) is 5,3 ± 0.25 cm–1. By means of infrared absorption spectroscopy a clear correlation between the disappearance of the divacancy (V2) in the temperature range 200–275 ºС and appearance of two absorption bands with their maxima at 825.8 and 839.2 cm–1 in irradiated oxygen-rich Si crystals is found. The band positioned at 825.8 cm–1 is assigned to a divacancy-oxygen defect V2O formed via an interaction of mobile V2 with interstitial oxygen (Oi ) atoms. The 839.2 cm–1 band is much more pronounced in neutron irradiated samples as compared to samples irradiated with electrons. We argue that it is related to a trivacancy–oxygen defect (V3O) formed via an interaction of mobile V3 with Oi atoms.


2007 ◽  
Vol 128 ◽  
pp. 207-212 ◽  
Author(s):  
Adam Worsztynowicz ◽  
Slawomir M. Kaczmarek ◽  
Elzbieta Tomaszewicz

New d-electron and rare-earth metal tungstates (CoRE2W2O10; CoRE4W3O16; Co2RE2W3O14 and NiRE2W2O10) were studied by the IR and EPR spectroscopy methods. The IR absorption bands with their maxima can be assigned to the symmetric and asymmetric stretching modes of W-O bonds in the joint of WO6 octahedra and also to the oxygen double WOOW bridge bonds. The wide, unstructured EPR powder spectra of these compounds and their temperature evolution have been analyzed and interpreted.


2016 ◽  
Vol 30 (32n33) ◽  
pp. 1650347
Author(s):  
Amarjeet ◽  
Vinod Kumar

[Formula: see text] ([Formula: see text] = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700[Formula: see text]C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz–5 MHz. Temperature dependence of the dielectric constant of [Formula: see text] was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz–5 MHz. It was found that the electrical conductivity decreases with increasing Cu[Formula: see text] ion content while it increases with the increase in temperature.


Author(s):  
К.К. ДАВЫДОВ

Проведена модификация сорбента, повышающего эффективность адсорбционной очистки кукурузного масла. Для получения сорбента использовали силикагель с поверхностью 300 м2/г, в качестве модификатора – гамма-аминопропилтриэтоксисилан из расчета 4 аминогруппы на 1 нм2поверхности. Силикагель (СГ) перед модификацией высушивали до постоянной массы. Навеску СГ диспергировали в разных органических растворителях – н-гексане, хлороформе и хлористом метилене – и вносили модификатор. Реакцию проводили при перемешивании реакционной смеси в ротационном вакуумном испарителе. Далее растворитель отделяли декантированием и промывали осадок. Остатки растворителя отгоняли под вакуумом. Полученный модифицированный СГ высушивали при заданной температуре. Для подтверждения модификации применяли метод ИК-спектроскопии с преобразованием Фурье на спектрометре FSM-1201. Для первичной обработки спектров использовали программное обеспечение F-Spec, для отнесения полос поглощения – IR Pal версии 2.0. С целью проверки способности синтезированного сорбента к сорбции карбонильных соединений использовали кукурузное масло, полученное в производственных условиях, после отбелки, с высоким значением анизидинового числа (около 8). Установлено, что использование модифицированного СГ значительно повышает эффективность адсорбционной очистки кукурузного масла: анизидиновое число масла, обработанного модифицированным сорбентом, снижается до 8 раз по сравнению с аналогичным показателем масла, обработанного немодифицированным СГ; на величину изменения анизидинового числа влияет дозировка модифицированного сорбента; свойства растворителя, в котором проводилась модификация, не оказывают существенного влияния на активность сорбента. Modification of the sorbent, which increases the efficiency of adsorption purification of corn oil, was carried out. Silica gel with a surface 300 m2/g was used to produce a sorbent, as a modifier – gamma-aminopropyltriethoxysilane at the rate of 4 amino groups per 1 nm2 surface. Silica gel (SG) before modification was dried to a constant mass. The sample of SG is dispersed in different organic solvents – n-hexane, chloroform and methylene chloride – and the modifier was introduced. Further, the solvent was separated by decanting, and the precipitate was washed. Residues of solvent are removed under vacuum. The obtaining modified SG was dried at a given temperature. Method of IR-spectroscopy with transform Fourier on the FSM-1201 spectrometer is used to confirm the modification. Software F-Spec is used for primary processing of spectra, IR Pal version 2.0 – for assignment of absorption bands. Corn oil obtained in production conditions, after bleaching, with a high anisidine number (about 8) was used to test the ability of the synthesized sorbent to sorption of carbonyl compounds. It was found that the use of modified SG significantly increases the efficiency of adsorption purification of corn oil: the anisidine number of oil treated with a modified sorbent is reduced to 8 times compared to the same indicator of oil treated with unmodified SG; the dosage of the modified sorbent affects the amount of change in the anisidine number; the properties of the solvent, in which the modification was carried out, do not have a significant effect on the activity of the sorbent.


2019 ◽  
Vol 1 (2) ◽  
pp. 1-7
Author(s):  
O.O. Shonekan ◽  
◽  
A.C. Otuka ◽  
D.K. Adeyemi ◽  
O.T. Fatunsin ◽  
...  

Background: Syzygium guineenses, (the most common and abundant specie in Nigeria) is a medicinal plant used by traditional practitioners in northern Nigeria for a variety of healing purposes. Objective: The main objective of this project was to carry out a comparison of antioxidant activities and Fourier Transform Infrared Spectrophotometric (FTIR) analysis on both methanol and hexane leaf extracts of S. guineenses. Methods: Phytochemical screening, Semi-quantitative DPPH (1,1-diphenyl-2-picrylhydrazyl)- dot blot assay and FTIR analysis were performed on both extracts to determine antioxidant activity and identify the functional groups present. Results: Phytochemicals tested for, were observed to be more prominent in the methanol extract than hexane. The in vitro antioxidant assay also revealed a more intense yellow colour of inhibition in methanol extract than the hexane extract. The FTIR spectra revealed different characteristic peak values with various functional compounds in both extracts. The methanol extract displayed major peaks of absorption at 3341 cm-1 (-OH) for alcohol, 1736 cm-1 (C=O) carbonyl group, 1161.83 cm-1, 1036.49 cm-1 (C-O) of esters. Other absorption bands like 1452.25 cm-1 and 1612.20 cm-1 for alkenes were present in both extracts. Conclusion: This result shows that the methanol extract of S. guineenseshas a higher potential of phytochemicals, antioxidants and functional groups than the hexane extract.


Author(s):  
N.U. Mulloev ◽  
◽  
N.L. Lavrik ◽  
J.O. Yusypova ◽  
N.A. Majidov ◽  
...  

An experimental method is proposed for determining the efficiency of the formation of intermolecular hydrogen bonds by determining the formation constant of the H-complex (K). The essence of the experiment to determine the value of K is that for one initial concentration of the proton donor, it is necessary to register the change in the optical density at the absorption wavelength of the monomers and the change in the optical density of the complexes of IR absorption bands at two concentrations of the proton acceptor. This approach was tested on the example of the interaction of butyl alcohol (proton donor) with 4-chloromethyl-1.3-dioxolane (proton acceptor). The obtained value of the equilibrium constant was 72.2 M-1. It is concluded that the proposed method for determining the value of K can be used not only in IR, but also in UV-visible spectroscopy.


Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Jose L. Rendon ◽  
Carlos J. Serna

AbstractHematites obtained by heating goethite gave different IR absorption spectra depending on the temperature of formation. Hematites formed between 250–600°C consisted of lath-like crystals (average size 0.4 ×0.08 µm) and showed, in accordance with theoretical predictions, very similar IR spectra whose absorption bands could all be assigned to surface mode vibrations. However, significantly different IR spectra were given by hematites formed between 700–950°C, the differences being correlated with variations in the size and shape of the particles. Differences observed in the IR spectra of powder hematite do not therefore justify new names for the mineral, as have been proposed in the literature.


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