Standard Wet Chemical Methods Research Articles

Hydrothermal treatment of perlite with caustic soda to produce metal silicate solutions

The effects of temperature, concentration of caustic soda and liquid to solid ratio on hydrothermal treatment of perlite with caustic solution to produce metal silicate solutions were investigated. The reaction was carried out in laboratory autoclave of 1 L capacity over a range of experimental conditions. The treatment time was kept constant at 1 hour. The chemical compositions of liquid products were analyzed by standard wet chemical methods. The results indicated that, under favorable conditions, aqueous metal silicate solutions with a high yield of about 80 percent, and having SiO 2/Na 2O molar ratios of 0.6 to 1 can be produced by this method.

A new method for determining aflatoxins in groundnut and groundnut cake using fourier transform infrared spectroscopy with attenuated total reflectance

AbstractA new analytical method was developed for the determination of aflatoxins in groundnut and groundnut cakes by Fourier transform infrared (FTIR) spectroscopy using horizontal attenuated total reflectance technique. Groundnut and groundnut cake samples were used in this study. The wave‐lengths were selected for the four types of aflatoxins—B1, B2, G1, and G2—and the standards prepared for earch by spiking some clean sample with the aflatoxins in concentrations of 0–1200 parts per billion. A partial least square regression was used to derive the calibration models for each toxin. The coefficients of determination (R2) of the calibration model were computed for the FTIR spectroscopy predicted values vs. actual values of aflatoxins in parts per billion. The R2 was found to be 0.9911, 0.9859, 0.9986, and 0.9789 for aflatoxins B1, B2, G1 and G2, respectively. Standard errors of calibration for groundnut samples were found to be 1.80, 2.03, 1.42, and 2.05 for aflatoxins B1, B2, G1, and G2, respectively. Calibration models were validated with an independent set of samples. The R2 of validation models were computed. The SD of the difference for repeatability of the FTIR method was found to be better than that of the chemical method. Based on the results obtained, FTIR spectroscopy can be a useful instrumental method for determining aflatoxins in oilseeds and oilseed cakes. With its speed and ease of data manipulation by computer software, it is a possible alternative to the standard wet chemical methods for a rapid and accurate routine determination of aflatoxin levels in food and feed.

Boiler Briquette Coal versus Raw Coal: Part I—Stack Gas Emissions

ABSTRACT Stack gas emissions were characterized for a steam-generating boiler commonly used in China. The boiler was tested when fired with a newly formulated boiler briquette coal (BB-coal) and when fired with conventional raw coal (R-coal). The stack gas emissions were analyzed to determine emission rates and emission factors and to develop chemical source profiles. A dilution source sampling system was used to collect PM on both Teflon membrane filters and quartz fiber filters. The Teflon filters were analyzed gravimetrically for PM10 and PM2.5 mass concentrations and by X-ray fluorescence (XRF) for trace elements. The quartz fiber filters were analyzed for organic carbon (OC) and elemental carbon (EC) using a thermal/optical reflectance technique. Sulfur dioxide was measured using the standard wet chemistry method. Carbon monoxide was measured using an Orsat combustion analyzer. The emission rates of the R-coal combustion (in kg/hr), determined using the measured stack gas concentrations and the stack gas emission rates, were 0.74 for PM10, 0.38 for PM25, 20.7 for SO2, and 6.8 for CO, while those of the BB-coal combustion were 0.95 for PM10, 0.30 for PM2 5, 7.5 for SO2, and 5.3 for CO. The fuel-mass-based emission factors (in g/kg) of the R-coal, determined using the emission rates and the fuel burn rates, were 1.68 for PM10, 0.87 for PM25, 46.7 for SO2, and 15 for CO, while those of the BB-coal were 2.51 for PM10, 0.79 for PM2.5, 19.9 for SO2, and 14 for CO. The task-based emission factors (in g/ton steam generated) of the R-coal, determined using the fuel-mass-based emission factors and the coal/ steam conversion factors, were 0.23 for PM10, 0.12 for PM2.5, 6.4 for SO2, and 2.0 for CO, while those of the BB-coal were 0.30 for PM10, 0.094 for PM2.5, 2.4 for SO2, and 1.7 for CO. PM10 and PM2.5 elemental compositions are also presented for both types of coal tested in the study.

Scanning electron microscopy, X-ray microanalysis, and thermogravimetric assessment of linen fabrics treated with crease-resisting compound

The physical, chemical, and thermal changes in fabrics treated with a commercial crease-resisting compound (CPNS) were investigated. The samples were analyzed by a scanning electron microscope equipped with an energy dispersive X-ray microanalyzer, elemental analysis, and differential thermogravimetry. X-ray microanalysis of the treated fabrics revealed that changes in gross integral counts of O, N, Mg, Al, Si, S, Cl, and Ca as a result of the treatments were related to the application rate of the compound. This result was broadly supported by mineral analysis data determined by standard wet chemistry methods. The effects of over- and undercuring were also investigated. In addition, the increase in nitrogen content as a result of the higher application rate can also be detected by EA. Differential thermogravimetric analyses of the samples showed distinct changes in the profile of the thermally stable fraction. This could be due to the formation of a crosslinked cellulose complex, which pyrolyzed at the significantly higher decomposition temperature of 481°C in comparison with 473°C for untreated material. The advantages of using instrumental techniques for assessing the efficiency of treatments are briefly discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1209–1219, 1999

Using near-infrared reflectance spectroscopy to predict carbon, nitrogen and phosphorus content in heterogeneous plant material.

The aim of this study was to produce calibration equations between near-infrared reflectance (NIR) spectra and the concentrations of carbon, nitrogen, and phosphorus in heterogeneous material: from living needles to litter in Pinus halepensis stands subjected to prescribed burnings. The aim was to determine whether calibrations should be conducted within each stage in the transformation of needles (local calibrations), giving relationships that were accurate but valid only for each particular stage, or whether it was possible to integrate the various forms of variation in needles (global calibrations) while retaining an acceptable accuracy. A principal component analysis calculated from the sample spectral data was used to distinguish three different sets, each sharing spectral characteristics and corresponding to three categories of needle: needles collected on the pines (N), falling needles (F), and litter (L), and each containing samples collected from the burnt sites and a control site. Samples representative of all the forms of variation in spectral properties were selected from within each category and their carbon, nitrogen, and phosphorus concentrations were measured using standard wet chemistry methods; these constituted the calibration sets n, f, and l. Calibrations were produced between the nutrient concentrations and the NIR spectra of the calibration sets n, f, and l and the grouped sets (n+f, f+l, n+f+l). The results of local calibrations made from each individual category showed that the carbon, nitrogen, and phosphorus concentrations were accurately predictable by NIR spectra. The global calibrations made by lumping together several categories were valid for a wider range of concentrations and for spectrally heterogeneous materials and in most cases were just as accurate as the local calibrations produced from each individual category.

Raman Spectroscopic Determination of the Degree of Cationic Modification in Waxy Maize Starches

ABSTRACT Waxy (essentially amylose-free) maize starch was chemically modified to varying degrees by treatment with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC), and the degree of cationic modification was determined by a standard wet chemistry method. FT-Raman spectra of the modified starches were taken, and a characteristic Raman band ∼761 cm−1 was found. This 761 cm−1 Raman band's intensity depended on the level of cationic modification of the starch. The ratio of intensity of the ∼761 cm−1 band to a ∼715 cm−1 C-C stretch Raman band (used as an internal standard) was plotted versus the amount of cationic modification derived by titration analysis, and a linear fit was obtained with a correlation of 0.998. The FT-Raman spectroscopy method presented here demonstrates a rapid non-destructive way to determine the level of cationic modification of waxy maize starch, and should be suitable for use with cationic modified starches of any amylose content.

Raman Spectroscopic Determination of the Degree of Succinate in Modified Waxy Maize Starches

ABSTRACT Waxy (essentially amylose-free) maize starch was chemically modified to varying degrees by treatment with succinic anhydride, and the degree of substitution was determined by a standard wet chemistry method. FT-Raman spectra of the modified starches were obtained, and indicated a characteristic ∼1730 cm−1 C=O stretch Raman band whose intensity was dependent on the degree of succinylation. The ratio of intensity of the ∼1730 cm−1 band to a ∼940 cm−1 C-C stretch Raman band (used as an internal standard) was plotted against the degree of succinylation determined by titration, and a linear fit was obtained with a correlation of 0.998. Hence FT-Raman spectroscopy represents a rapid non-destructive method to determine the degree of succinylation of modified waxy maize starch, and should be suitable for use with succinylated starches of any amylose content.

Iron ore processing -- in-situ monitoring

Mossbauer spectroscopy has been used to provide detailed quantitative insight into the reaction products present at different stages of the processing/reduction of iron ores. Typical phases include: α-Fe2O3; Fe3O4; Fe1-xO; Fe3C and Fe, which are in agreeement with the results obtained using standard wet chemistry methods. As an extension of this post reaction examination of products, we have used Mossbauer spectroscopy for in-situ measurements during the week long operation of an iron ore processing pilot plant. Such in-situ measurements allow optimal control of the plant to be obtained with, depending on the strength of the source, a time constant of ~ 1 h.

Application of Near-Infrared Reflectance Spectroscopy in the Measurement of Carbon, Nitrogen, and Phosphorus in Seston from Oligotrophic Lakes

The application of near-infrared spectroscopy (NIRS), widely used in the agricultural, food, and pharmaceutical industries, is extended to the measurement of C, N, and P in seston from oligotrophic lakes at the Experimental Lakes Area, northwestern Ontario. Seston from 150-mL aliquots of lake water from several depths in two lakes on one mid-June sampling date was collected on Whatman GF/C filters and measured first by NIRS then analyzed by standard wet chemistry methods. Correlation between chemically measured and NIRS-predicted values gave coefficients of determination between 0.913 and 0.982. The rapid, low-cost, nonchemical, nondestructive, efficient analysis of C, N, and P in seston by NIRS is feasible.

The 10-km sample cell

Airborne near-IR spectrometers can now scan the Earth at high resolution and could soon be used to create regional and global maps of environmental responses to pollution. They will trace regional patterns of nitrogen deposition and its impact on the environment by following the changes it produces in the chemical composition of forest foliage. To track foliar response to increased nitrogen, visible/near-IR spectrometry is used in conjunction with standard wet chemical methods for determining nitrogen, lignin, and cellulose in leaf samples from targeted forest sites. 2 figs.

A HYDROGEOCHEMICAL AND STREAM SEDIMENT SURVEY OF THE ASKRIGG BLOCK IN THE NORTHERN PENNINE OREFIELD

SUMMARY A regional hydrogeochemical reconnaissance survey of the southern part of the northern Pennine orefield (Askrigg Block) was undertaken at a sampling density of 1 per 2km 2 . For comparison a stream sediment survey using a sample density of 1 per 7km 2 was also conducted. The water samples were analysed for Na, K, Ca, Mg, Fe, Mn, Sr, Zn, Cu, Ag, Pb, Cd, Co, and Ni by atomic absorption spectrophotometry. Colourimetric methods were used to determine NO 2 , B, and Si, and Fe, NO 2 and pH were analysed by a specific ion analyser. Li was determined by flame photometry and standard wet chemical methods were employed in the determination of SO 4 , Cl, CO 2 , Fe 2+ and Fe 3+ . The stream sediments were analysed by X-ray fluorescence spectrometry. The analytical results (>10,000) were interpreted using multivariate statistical techniques. Examples of geochemical patterns and anomalies related to geology, pollution and mineralisation are identified. Silica analyses have delineated the Namurian outcrop. Certain Pb, Zn, Cu, V, Na and Cl anomalies are attributed to pollution from agricultural fertilisation and old smelting and/or dressing sites. Zn, F, Pb, Cu, Ni, Co and Ba anomalies are coincident with known mineralisation as well as, as yet, unproven ore deposits.