Determination of SiO 2 in lime mud by gravimetry

A simple and rapid method for the determination of SiO2 in lime mud used in current sulfate pulping practice is reported. The lime mud samples are treated three times with 2.5 mL of 6 mol/L hydrochloric acid. The samples are nearly evaporated to dryness two times and the third time to complete dryness. To determine the exact SiO2 content of the residue, it is treated with an excess of concentrated hydrofluoric acid and a little hydrochloric acid, and the silica is expelled as volatile silicon tetrafluoride. The sample treatments take about 1.5 h and the heating periods take a total of about 3.5 h. The SiO2 results were evaluated by analyzing National Institute of Standards and Technology St…

Determination of Calcium in Certain Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Studies of Some Spectral and Interelement Effects at Different Wavelengths

Abstract Four analytical wavelengths (393.366, 396.847, 317.933, and 422.673 nm) were used to determine Ca in 2 fertilizers by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Matrix effects were studied by adding to real fertilizer solutions fertilizer elements that are known or believed to interfere with Ca determination. Matrix effects were calculated by multiple linear regression. Interference was caused by S, K, or B. At 422.673 nm, the interference of B and K is a spectral effect, and at 396.847 and 317.933 nm, the interference of S and K is an interelement effect. At 393.366 nm, no linear interference was found. The best wavelength for determining Ca in fertilizers …

Conversion of peat and coal nitrogen through HCN and NH3 to nitrogen oxides at 800 °C

The conversion of fuel nitrogen through HCN and NH3 to nitrogen oxides (N2O, NO and NO2) was studied using an entrained-flow reactor at 800 °C with one coal and four peats at 5 and 1% O2. The ON ratios of the fuels were between 7 and 20. A clear dependence was found between the HCNNH3 ratio measured just after the vigorous pyrolysis step and the N2ONO ratio in the flue gas when these were plotted as a function of the initial ON ratio of the fuel.

Determination of platinum and iridium in reforming catalysts by second derivative and absorptiometric spectrophotometry

Investigations on the spectrophotometric determination of platinum as a complex formed by tin(II)chloride in hydrochloric acid are reported. The determination of platinum was found to be interfered with by iridium, because it also forms a complex with tin(II) chloride. The features of the derivative absorption spectrophotometry for the quantitative determination of platinum and iridium was also studied. The analytical application of the method for the determination of platinum and iridium in catalysts was investigated.

Iron Determination in Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Study of Spectral and Interelement Effects at Different Wavelengths

Abstract Four analytical wavelengths of iron (238.204, 239.562, 259.940, and 240.488 nm) were tested for determination of Fe in fertilizers by inductively cou pled plasma atomic emission spectroscopy (ICP AES). Variations in measurements were caused by the changing interference pattern at different wave lengths evaluated by multiple linear regression. Thus, results obtained with different wavelengths are not comparable. Ca, P, and K were typical ele ments causing interference in almost all examined Fe wavelengths. Wavelength Fe II 238.204 nm is the best wavelength for determination of Fe in fertiliz ers by ICP-AES. Method accuracy is ± 8% at the ex amined Fe levels in fertilizers.

Importance of iron and aluminium in rapid and slow combustion of peat

Abstract The effects of Fe and Al on peat combustion and the formation of nitrogen oxides were studied under conditions of rapid combustion in an entrained flow reactor, and under conditions of slow combustion in a thermobalance and a differential scanning calorimeter. Iron had a strong catalytic effect on both the slow and rapid combustion, and it decreased the ratio of N2O to NO in the combustion gases. A decrease in the content of inorganic compounds decreased reactivity, probably because of the decrease in iron content. Aluminium did not have a detectable catalytic effect on the combustion rate but it depressed the formation of nitrogen oxides slightly. The chemical treatment to increas…

Determination of antimony, arsenic, bismuth and copper by inductively coupled plasma atomic emission spectrometry in the electrorefining of copper

Inductively coupled plasma atomic emissionspectrometry (ICP-AES) has been applied as a rapid and routine method for the analysis of process electrolytes in the electrorefining of copper. Antimony, arsenic, bismuth and copper have been selected as major electrolyte constituents. For these elements profound statistical studies of spectral and interelement effects have been carried out. For As, Bi and Sb two analyte wavelengths have been selected, and for Cu one relatively insensitive analyte line has been chosen due to the high Cu concentration in samples. Best analytical lines were: As at 193.759 nm, Bi at 306.772 nm, Sb at 206.833 nm and Cu at 216.953 nm. Multiple linear regression proved t…

Determination of Magnesium in Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Studies of Some Spectral and Interelement Effects at Different Wavelengths

Abstract Four analytical wavelengths of magnesium were tested for determination of Mg from fertilizers by inductively coupled plasma atomic emission spectroscopy (ICP-AES): 202.528, 285.213, and 383.826 nm (Mg I) and 279.553 (Mg II). The effects of fertilizer matrix elements on Mg determination were examined by adding matrix elements to fertilizer solutions. Multiple linear regression calculations proved a valuable technique for evaluating the effects of matrix elements on Mg determination. The observed interferences at Mg wavelengths may be both spectral and interelement. Interelement effects were typically caused by Na, K, and Ca, and spectral effects, by P, Fe, and S. The best wavelength…

Retention of Molybdenum(VI) by Three Finnish Mineral Soils

Retention of molybdate by three Finnish mineral soils from 10−4 and 10−5 M sodium molybdate solutions at room temperature was investigated at pH 2.3–7.5. In the adsorption experiments 0.02 M KCl wa...

UV-spectrophotometric determination of tetrazene

Determination of NH(3) in pyrolysis gases by ammonia selective electrode.

The suitability of ion-selective electrode for the determination of ammonia in pyrolysis gases of fossil fuels was studied. The ammonia was absorbed into acidic solution and two kinds of determination methods were carried out. The ammonia was either measured directly from the acid solution, or ammonia was first released into the gas phase and then determined (air gap method) by the ammonia selective electrode. The electrode functioned well in both cases, but the linear calibration range was rather narrow, slightly more than one tenfold. The quantitative detection limit in the water phase was 5 × 10−6M (0.085 ppm) NH3 and in gas phase operation solutions above 5 × 10−4M (8.5 ppm) NH3 it was …

The determination of certain major and minor elements in geological samples by inductively coupled plasma atomic emission spectrometry. Some interference problems with the analysis of geological standard reference materials and nutrition supplements

Direct ICP-AES measurements of the digested geological standard reference material samples yielded the wrong information about their composition. The differences between certified and measured concentrations of the samples were due to the complicated sample matrix. The measured concentrations can be successfully corrected by using a multiple linear regression technique. The correction is based on the multiple regression line calculated from the analytical results at synthetic mixtures of matrix elements, where concentrations varied on five levels. There were no significant (P = 0.05) differences between certified and measured concentrations in standard reference materials after the correcti…

Retention of Vanadium(V), Molybdenum(VI) and Tungsten(VI) by Kaolin

Abstract The ability of kaolin (approximately H2Al2Si2O8 · H2O), a well known clay mineral constituent, to retain V(V) andMo(VI) species from 10−5 and 10−4 M solutions, and W(VI) species from 10−4 M solutions was investigated in the pH range 2–7.5 using a solid/liquid ratio 1:100 (w:v). The equilibration time in the adsorption studies was 72 h, and the shaking time in the desorption studies was 17 h. 0.02 M KCl was used as ionic medium and desorbing liquid. V(V), Mo(VI) and W(VI) were all retained by kaolin to some extent, and the amounts of the elements which could be washed away from kaolin with 0.02 M KCl were very small. The pH dependence of the adsorption was considerable: when added a…

Determination of cobalt, copper, iron, nickel and zinc in cemented tungsten carbides with cobalt as a binder by FAAS: Matrix effect control by multivariate technique

A new approach for the determination of cobalt, copper, iron, nickel and zinc in cemented tungsten carbides with cobalt as a binder by flame atomic absorption spectrophotometry (FAAS) is reported. Real samples were dissolved in phosphoric, hydrochloric and nitric acid. PTFE bomb or alternatively small amounts of HF were used for the enhancement of the recovery of the elements investigated. Synthetic samples were used for interference studies. Multiple linear regression was applied for the control of matrix effects and it proved to be very effective in the search for interfering elements. Using simple acid based standards, all investigated elements could be determined sequentially in a compl…

Determination of Boron in Fertilizers by Inductively Coupled Plasma-Atomic Emission Spectrometry: Studies of Some Spectral Interferences at Different Wavelengths

Abstract The most sensitive analytical wavelengths of boron cannot be used in the determination of boron in fertilizers by inductively coupled plasma-atomic emission spectrometry because of spectral interference by potassium, phosphorus, and iron. For the 4 wavelengths of boron investigated, it was noticed that, at the same wavelength, the pattern of spectral interference changes according to fertilizer composition. The spectral interference patterns at the 4 analytical boron wavelengths were studied by adding matrix elements typically found in fertilizers to real fertilizer samples. When levels of added matrix elements correlate less than 0.2 to each other, the effect of added matrix eleme…

Determination of Sulfur in Fertilizers by Inductively Coupled Plasma-Atomic Emission Spectrometry: Spectral and Interelement Effects at Various Wavelengths

Abstract Three analytical wavelengths (180.731,182.037, and 182.625 nm) were tested for determination of sulfur in 2 fertilizers by inductively coupled plasmaatomic emission spectrometry (ICP-AES). Variable S results at 182.037 nm were caused by a downward sloping background shift (Fe line at 181.851 nm) during measurement of the sample solutions. At 182.625 nm an emission peak doublet, 182.619/182.635 nm, was observed from which the instrument selected the measurement peak. A shift from calibrated peak 182.619 nm to noncalibrated peak 182.635 nm occurred when the S/B ratios were ≤22-31 in the fertilizer samples examined. For the 3 wavelengths of S investigated, the pattern of spectral and …

Optimization of the gravimetric determination method of nickel as dimethylglyoximate for nickel raw materials

The method parameters of an almost one century old method for analyzing nickel as dimethylglyoximate were critically examined for the analysis of nickel raw materials and many of the method parameters were observed to have a significant effect on the Ni recovery. Thus, because the Ni precipitation method parameters vary a lot in analytical literature and also in practice, the obtained Ni results by different methods are not comparable. During this study it was found that the double precipitation worked out perfectly in eliminating the effects of impurity elements. The residual Ni content in the filtrates should also be measured to obtain accurate and precise Ni results. In complexing the im…