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Trace metals in water were preconcentrated with silica gel modified with salicylaldoxime and determined by AAS. Optimum conditions for the maximum recovery of metal ions, viz. Cu(II), Ni(II), Co(II), Zn(II) and Fe(III), for both batch and column methods were developed. The efficiency of the adsorbent with respect to different experimental conditions was established.
The thin-layer chromatographic (TLC) behaviour of 64 ions including Zr(IV) and Hf(IV) has been surveyed on systems composed of silica gel and of nitric acid and nitric acid-hydrogen peroxide media. In the 0.5 mol l -1 HNO 3 -3% (w/v) H 2 O 2 solution, only Hf(IV) adsorbed very strongly, whereas Zr(IV) and many other ions showed no or weak adsorption. Stepwise...
The reaction of silica gel and Stober beads of silica with ammonia was studied in aqueous medium using a high frequency dielectric method. Measurements of the complex impedance of silica pulps in both static and dynamic modes were found to be a new rapid, sensitive and non-destructive way for the in situ characterisation of the surface silica ionisation process in aqueous ammonia. The influence of...
Dithioacetal derivatives with different para-substituents, X H, CH 3 , OCH 3 , Cl and NO 2 were synthesized and chemically immobilized on the surface of silica gel for the formation of five newly synthesized silica gel phases (I-V). Characterization of the silica gel surface modification by the organic compounds was accomplished by both the surface coverage determination as...
Organic ligand with carboxyhydrazide functional group was immobilised on the surface of silica gel and the metal binding capacity of the ligand-embedded silica was investigated. The functional group was covalently bonded to the silica matrix through a spacer of methylene groups by sequential reactions of silica gel with dibromobutane, malonic ester and hydrazine in different media. Surface area value...
New chelating sorbents are prepared by 3,3',4',5,7-pentahydroxyflavone adsorption from butanol and acetone-hexane (1:4) solutions, characterized by isotherm of sorption, IR-spectroscopy and studied for pre-concentrating and sorption-spectroscopic determination of Sn(IV). The solid-phase Quercetin with satisfactory analytical characteristics was formed by adsorption from acetone-hexane (1:4) mixture...
A new chelating matrix has been prepared by immobilizing 1,8-dihydroxyanthraquinone (DHAQ) on silica gel modified with (3-aminopropyl)triethoxysilane. After characterizing the matrix with thermogravimetric analysis (TGA), cross polarization magic angle spinning (CPMAS) NMR and diffuse reflectance infrared fourier transformation (DRIFT) spectroscopy, it has been used to preconcentrate Pb(II), Cd(II)...
The silica gel modified with (3-aminopropyl-triethoxysilane) was reacted with 5-formyl-8-hydroxyquinoline (FHOQ x ) to anchor 8-quinolinol ligand on the silica gel. It was characterised with cross polarisation magic angle spinning (CPMAS) NMR and diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy and used for the preconcentration of Cu(II), Pb(II), Ni(II), Fe(III), Cd(II),...
Silica gel was modified firstly with aminepropyltrimethoxisilane obtaining the matrix named as SILNH 2 . The SILNH 2 silica reacted subsequently with thioglycolic acid Sil-Ntga. The elemental analysis showed the presence of 0.98mmolg −1 of organic moieties immobilized on silica. Infrared and 13 C NMR spectroscopic data in conjunction with thermogravimetric measurements...
The adsorption of DPKSH onto silica gel was investigated, at 25+/-1 o C and pH 1, 4.7 and 12. For the same DPKSH concentration interval, the minimum required time of contact for adsorption maximum at pH 4.7 was smaller than at pH 1 and the maximum amount of DPKSH adsorbed per gram of silica at pH 1 is smaller than at pH 4.7. At pH 12 the DPKSH adsorption onto silica gel was not significant...
Microwave-assisted desorption (MAD) coupled to in situ headspace solid-phase microextraction (HS-SPME) was first proposed as a possible alternative pretreatment of samples in absorbent collected from workplace monitoring. Aniline collected on silica gel was investigated. Under microwave irradiation, the aniline was desorbed from silica gel and directly absorbed onto the SPME fiber in the headspace...
Silica gel was firstly functionalised with aminopropyltrimethoxysilane obtaining the aminopropylsilica gel (APSG). The APSG was reacted subsequently with morin yielding morin-bonded silica gel (morin-APSG). The structure was investigated and confirmed by elemental and thermogravimetric analyses, IR and 13 C NMR spectral studies. Morin-APSG was found to be highly stable in common organic solvents,...
Pretreatment of silica gel sample containing 1-naphthylamine by microwave-assisted desorption (MAD) coupled to in situ headspace solid phase microextraction (HS-SPME) has been investigated as a possible alternative to conventional methods prior to gas chromatographic (GC) analysis. The 1-naphthylamine desorbs from silica gel to headspace under microwave irradiation, and directly absorbs onto a SPME...
α-PW 12 O 403− (PW 12 ) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH 3 PW 12 ) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry...
A new material for solid-phase extraction of Pb(II) was prepared using chemically functionalized silica gel with alizarin violet. This material is stable in 6molL −1 of HCl, 6molL −1 of H 2 SO 4 , common organic solvents and pH 1.0–9.0 aqueous solutions. The influences of analytical parameters including pH of the aqueous solution, amount of the functionalized silica...
This paper has demonstrated the study on the adsorption kinetics of orthoxylene on silica gel with a novel experimental methodology. In the method, there was a differential adsorption bed (DAB) where the solid adsorbent always contacted with the same bulk concentration of the adsorbate vapor, and the DAB was monitored with near-infrared diffuse reflectance spectroscopy (NIRDRS) continuously as well...
The present work describes the development of an amperometric sensor based on hemin immobilized on a titanium oxide modified silica toward detection of artemisinin (ARN) in neutral medium at an applied potential of −0.5V vs. Ag/AgCl. The sensor presented its best performance in 0.1molL −1 phosphate buffer solution, at pH 7.0. After optimizing the operational conditions, the sensor provided...
A new method that utilizes 1-(2-aminoethyl)-3-phenylurea-modified silica gel as a solid-phase extractant has been developed for preconcentration of trace Sc(III) prior to the measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace level of Sc(III) were optimized using batch and column procedures in detail. The optimum...
The paper describes a sensitive and highly stable label-free electrochemical impedance immunosensor for the determination of aflatoxin B 1 (AFB 1 ), which is based on the formation of silica gel–ionic liquid biocompatible film on the glassy carbon electrode. The electrochemical performances of the sensor were investigated by electrochemical impedance spectroscopy using a Fe(CN) ...
We have synthesized the 1,3-alternate 25,27-dioctyloxy-26,28-bis-[3-aminopropyloxy]-calix[4]arene and then immobilized onto γ-chloropropylsilica gel (CPS). The high-performance liquid chromatographic behavior of some aromatic hydrocarbons, phenolic compounds, aromatic amines and drug compounds was studied on this 1,3-alternate-calix[4]arene-bonded silica gel stationary phase (CIMS). The effect of...
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