HNO3 Treatment Research Articles

Effect of Carbon Adsorbent Surface Properties on the Uptake and Solvent Regeneration of Phenol

An investigation was made of the effects of surface properties on the uptake of phenol by carbonaceous adsorbents and on subsequent regeneration by acetone leaching. As-received carbons derived from different source materials were evaluated at pH values 2 and 9, and the surface properties of selected adsorbents were varied by surface oxidation with concentrated HNO3 and/or heat treatment under nitrogen. Carbons derived from different source materials exhibited similar total uptake and reversible (acetone extractable) uptake at pH 2 but exhibited a wide range of reversibility at pH 9, conditions that promote oxidative coupling reactions. Surface acidity was investigated as a factor contributing to the reversibility of as-received carbons, and surface oxidation was evaluated as a means of improving regenerability. Oxidation of coal- and wood-based adsorbents with concentrated HNO3 increased surface acidity as measured by Boehm titration techniques and reduced the uptake of phenol but increased the reversibl...

Preparation and characterization of bimodal porous carbons derived from a styrene-divinylbenzene copolymer

A styrene/divinylbenzene copolymer has been used as precursor for making porous carbons with bimodal pore size distributions (i.e., with both microporosity and mesoporosity). Pretreatment of the as-received copolymer by mild oxidation in air, significantly increased the carbon yield after carbonization. Reactivity studies of the polymer-based chars to CO2 clearly show the influences of some important factors such as carbonization temperature, heating rate, soak time on char reactivities. Bimodal porous carbons were prepared by carbonization of the preoxidized styrene/divinylbenzene copolymer in N2, followed by activation in CO2 at different temperatures to different levels of burnoff. The pore structures of the porous carbons produced have been characterized by various techniques such as gas adsorption and mercury porosimetry. The surfaces of the porous carbons produced, and a commercial carbon adsorbent, have been modified with HNO3 and H2O2 treatment at various conditions. Characterization of the surface oxygen functionality, both quantitatively and qualitatively, has been achieved using techniques such as Linear Temperature Programed Desorption (LTPD) and selective neutralization of bases.

Influences of acid treatments of active carbons on NO reduction over carbon-supported copper oxides

Active carbon supported copper oxides were used in NO reduction. The conversions of NO reduction depends strongly on surface oxygen-containing groups on the active carbons, among them the carboxyls and lactones favored remarkably the NO reduction. However, hydrochloric acid treatment led to the decomposition of the carboxyls and lactones on C2 and C3, decreasing their reactivities for NO reduction. Concentrated HNO3 treatment of active carbon produced higher conversions of NO reduction at relatively low temperatures due to the marked increase in the amounts of the carboxyls and lactones.

The effect of chromium enrichment in the film formed by surface treatments on the corrosion resistance of type 430 stainless steel

The effect of chromium concentration in the surface film formed by surface treatments on the corrosion resistance of Type 430 stainless steel was studied. It was found that the chromium content depends on the surface treatment method. HNO3 treatments result in a significant enrichment of chromium in the surface film on the Type 430 stainless steel, and the chromium enrichment increases with increasing HNO3 concentration. The pitting potential (Ep), corrosion potential (Ec) and polarization resistance (Rp) are changed by the chromium enrichment (SCr) in the surface film formed by treatment. The higher the SCr value, the higher the Ep, Ec and Rp values.

Immobilization of a 15N-labeled nitrate addition by decomposing forest litter.

Effects of chronic HNO3 and H2SO4 additions on decomposition of senesced birch leaf, beech leaf, spruce needle, and wood chip litters were examined. Litters were incubated for up to 4 years in fiberglass mesh (1 mm) bags on experimental plots in a mixed-species forest near the Bear Brooks Watershed Manipulation (BBWM) site in eastern Maine, United States. Plot treatments included HNO3 additions at 28 and 56 kg N·ha-1·year-1, H2SO4 additions at 128 kg S·ha-1·year-1, and a combined HNO3 and H2SO4 treatment at 28 kg N and 64 kg S ·ha-1·year-1. The 15N content of all NO3 added was artificially increased to 344% δ15N. Litter bags were collected each fall and analyzed for organic matter loss, nitrogen concentration, and 15N abundance throughout the 4-year experiment. Extractive (non-polar-soluble+water-soluble), cellulose (acid-soluble), and lignin (acid-insoluble) fractions were analyzed for the first 2 years. In wood chips, nitrogen additions increased mass loss and N concentration, but not the mass of N after 4 years. Neither N nor S additions had large effects on mass loss, N concentration, or N content of leaf litters. All litters immobilized and mineralized N simultaneously, but we were able to place a lower bound on gross N immobilization by mass balancing 15N additions. Birch and spruce litters showed net mineralization, while beech leaf and wood chip litters showed net immobilization. Net immobilizing litters were those with the highest initial cellulose concentration (wood chips=80% beech leaves=54%), and we attribute the higher capacity for immobilization to more readily available carbon. Lignin mass increased initially in all litter types except spruce needles. Also, extractives in net immobilizing litters either increased initially (wood chips) or decreased at a slower rate than bulk litter (beech leaves). We calculate the potential of decomposing litter to immobilize exogenous nitrate in this system to be 1-1.5 kg N·ha-1·year-1, which is about half of the usual NO3 deposition at this site, but only a small fraction of the experimental addition.

Response of Buried Mineral Soil Bags to Experimental Acidification of Forest Ecosystem

AbstractAt Bear Brook Watershed in Maine, H2SO4 and/or HNO3 was added to 15 by 15 m plots (three replicates per treatment) from 1988 through 1990. Total loading above ambient treatments for the 3 yr was 0 (control), 5100 (low S, low N), 10 200 (high S and N + S), and 11 950 (high N) molc ha−1 yr−1. Changes in soil chemistry were evaluated using tension lysimeters and buried mineral soil bags placed below the forest floor before treatments were initiated. Total soil S was highest in the high S treatment (355 mg S kg−1 soil), intermediate in the low S and N + S treatments (314 and 310 mg S kg−1 soil, respectively), and lowest in the low N, high N, and control treatments (278, 275, and 270 mg S kg−1 soil, respectively). Differences in total S were mostly attributed to phosphate‐extractable SO4, although smaller changes in ester sulfate and C‐bonded S were also detected. Low pH and elevated SO4 in solution resulted in increased SO4 in solution resulted in increased SO4 adsorption. There were no differences caused by treatments in N or C constituents in the soil bags, although N was strongly linked with C (r = 0.86). Nitric and sulfuric acid additions lowered soil pH (H2O) from 4.83 in the control to 4.67 and 4.70, respectively. Sulfuric acid treatments increased exchangeable Ca to 0.32 cmolc kg−1 compared with 0.24 cmolc kg−1 in the control, whereas HNO3 treatments decreased Ca to 0.18 cmolc kg−1. A strong correlation (r = 0.94) between exchangeable Ca and base saturation reflected the quantitative dominance of exchangeable Ca among base cations. Similarities in effects of the N + S and the low S treatments were due to identical additions of SO4 and the absence of a marked effect of NO3 additions on the mineral soil. Changes in the chemistry of the buried mineral soil bags can be explained by both the effects of H2SO4 and HNO3 additions as well as pedogenic processes.

Sequential fractionation of chromium and nickel from some serpentinite‐derived soils from the eastern Transvaal

Abstract Soils derived from ultramafic serpentinitic rocks are inherently infertile. These soils support plant species that are able to hyperaccumulate both chromium (Cr) and nickel (Ni). This study was conducted to determine the efficacy of a sequential extraction technique in explaining sources of Cr and Ni that are taken up by plant species growing on these soils. The sequential extraction of soil samples obtained from the eastern Transvaal involved the following reagents: H2O and 0.5M KNO3, 0.5M NaOH, 0.05M Na2EDTA, and 4M HNO3. More than 95% of the total Cr was extracted by HNO3 while the remaining extractants fell into the order NaOH > EDTA ≫ KNO3 + H2O. There would appear to be a loose correlation between easily soluble Cr (KNO3 + H2O) and the uptake of Cr by the plant. A somewhat higher proportion of Ni was extracted prior to the HNO3 treatment although amounts removed by KNO3 + H2O were all less than 1% of the total. It would appear that plant species growing on these soils are able to accumulate these elements from sources other than those considered easily available. A highly significant coefficient of determination was obtained between Ni extracted by oxalate and EDTA extractable. The fraction extracted by the steps in the sequential procedure can be related to exchangeable and sorbed (KNO3 and H2O) and an easily acid soluble inorganic fraction (HNO3). The NaOH and EDTA fractions are probably related to the Cr and Ni bound in the form of organic complexes and associated with iron oxides.

Elementary composition, humus composition, and decomposition in soil of charred grassland plants

Abstract Charred plant residues collected after the burning of grassland vegetation in which Susuki plants predominated (Eulalia, Miscanthus sinensis A.), were divided into 5 particle size fractions of >2, 1-2, 0.5-1.0, 0.25-0.5, and <0.25 mm using sieves. 1) The percentage distribution of organic matter in the charred plant residues was higher in the larger particle size fractions, and the reverse was true for the distribution of ash. 2) The contents of carbon, hydrogen, and oxygen of each fraction on an oven-dried basis decreased with decreasing particle size, but the ash content showed an inverse relationship. No regular trend was found between the nitrogen content and the particle size. 3) The atomic H/C and O/C ratios of each fraction and other data suggested that dehydrative condensation took place during the burning of the grassland vegetation studied. 4) The amounts of NaOH-extractable materials from each fraction which were very small significantly increased after the HNO3 treatment of the fractions. The extraction ratio of organic matter, amounts of humic and fulvic acids, and ratio of humic acid in the NaOH-extractable organic matter decreased with decreasing particle size. The humic acids produced belonged to A type, and their absorption curves were similar to those of A type soil humic acids. 5) When several fractions were separately added to a sample of volcanic ash soil and incubated at 25°C under moist conditions, their fractions were hardly decomposed by microorganisms even after 40 weeks.

Effect of InGaAsP surface treatment for indium-tin-oxide/InGaAsP/GaAs solar cells

The performances of n-indium-tin-oxide (ITO)/n-InGaAsP/p-GaAs solar cells in which the chemical treatment at the ITO/InGaAsP heterointerface is varied are compared: HNO3 treatment, HCl treatment, and nontreatment. The cells with HNO3 treatment show good solar-cell performance in spite of large lattice mismatch between ITO and InGaAsP. Others do not show even rectifying behavior. The structure of the cells with HNO3 treatment is thought to be a semiconductor-insulator-semiconductor structure, and its current model follows the tunneling model. By Auger analysis the oxide layer, which is thought to be formed by HNO3 treatment, was ascertained. Using the heterostructure back-surface field for the cells with HNO3 treatment, the highest efficiency attained so far is 10.9% (total area) under AM1 illumination normalized to 100 mW/cm2; the corresponding open-circuit voltage, short-circuit current density, and fill factor are 0.56 V, 28.8 mA/cm2, and 0.677, respectively.

Aluminum Leaching by Mineral Acids in Forest Soils: I. Nitric‐Sulfuric Acid Differences

AbstractIn laboratory studies simulating snowmelt leaching of forest soils, HNO3 leached more Al than did H2SO4 from soil columns containing a forest floor‐spodic horizon sequence (FF/Bs) representative of high elevation forest soils and watersheds thought to be sensitive to acidification by acid precipitation. Increasing the HNO3 concentration 100‐fold (pH 5 to 3) increased total Al concentration in leachates from 0.70 to 0.85 mM, while increasing H2SO4 concentration had no effect. Addition of pH 3 H2SO4 to the FF/Bs columns raised leachate pH relative to pH 3 HNO3 and control treatments, and resulted in the lowest Al concentrations of all treatments in the first three of four sequential leachings. In albic (E) and ochric (A) mineral soil horizons below a forest floor, there were no differences between the acids and no effects of changing acid concentration. Concentrations of Al leached by the acids did not differ from those in control treatments. The differences in effects of HNO3 and H2SO4 on soluble Al and pH in the Bs horizon and the lack of effect of either acid in the E and A horizons imply that the type of mineral horizon below the forest floor and the kind of acid leaching through these horizons are pertinent to predicting lake acidification in diverse forested watersheds. The results also have implications for pollution control strategies focusing solely on SO2 emissions and designed to mitigate lake acidification.

Textural study of a coal from villanueva de rio y minas (sevilla, spain) and of samples prepared from it by acid and heat treatments

AbstractA coal with high inorganic matter content from the mine of Villanueva de Rio y Minas (Sevilla, Spain) (VRMO) was classified by following the ASTM norms as a high volatile matter A bituminous coal. The starting coal was treated either with HCl (VRMH) or thermally at 1000°C for 2 h (VRMOC), the resultant yield values (referred to as VRMO, dry) being, respectively, 97 and 79%; also VRMH was either treated with HNO3 (VRMN) or HF (VRMF), and the yield values (referred to as VRMH, dry) of the process were then 95 and 59%. The textural characterization of samples was effected by adsorption of CO2 at 273 K and of N2 at 77 K, as well as by mercury porosimetry. VRMN presents the highest value of the apparent surface area (SD‐R=219 m2 g−1) (CO2, 273 K) and of the specific surface area of mesopores and macropores (Sme+ma=5.2 m2 g−1) (N2, 77 K), while the greatest value of the cumulative specific surface area of macropores (Sma=1.2 m2 g−1) (mercury porosimetry) corresponds to VRMOC; S values are expressed on a per gram of original sample basis. The micropore volume accessible to CO2 at 273 K increases in both the HCl and the HNO3 treatment and decreases in the HF and heat treatments. The HCl and HNO3 treatments produce an increase of the mesoporosity; the HF treatment seems to affect in a special way the mesoporous texture. Furthermore, the heat treatment gives rise to a notable development of the macroporosity.

Potential of human polymorphonuclear leukocytes to synthesize and secrete sulfated proteoglycans

To analyze the function of proteoglycans (PG) in different types of leukocytes, both the relative amounts and specific types of proteoglycans produced by cultured human peripheral blood polymorphonuclear leukocytes (PMN) were were determined and compared to mononuclear leukocytes (PBMC). Media from 3-day cultured PMN contained significantly less (less than 10%) 35SO2-4-labeled PG than media from PBMC cultures. Incorporation of 35SO2-4 into cell-associated material was comparable for both types of white blood cells. In contrast to PBMC, PMN could not increase their synthesis or secretion of PG after exposure to concanavalin A or phorbol-12-myristate-13-acetate. Various inducers of leukocyte chemotaxis also failed to enhance PG production by PMNs. Release of prelabeled PG from PMNs could be induced by exposure to either opsonized or unopsonized zymosan (yeast) as well as the bacteria S. aureus, suggesting that particle ingestion may be accompanied by PG exocytosis. Both chondroitinase ABC and AC digested greater than 90% of PMN 35S-labeled material in media and 75% in cell lysates; HNO3 treatment removed less than 5% of N-linked 35SO4 from radiolabeled media and 25% from cells. Treatment with 0.5 N NaOH released shortened glycosaminoglycan chains from 35S-labeled PMN cell lysates. beta-D-xylosides did not stimulate an increase in polysaccharide chain production by cultured PMNs. These data suggest that PMNs can produce chondroitin 4-sulfate PG whose synthesis is not affected by treatments that alter PMN functions; in contrast to PBMCs, PMNs will actively release these molecules when exposed to micro-organisms that stimulate phagocytosis.

Influence of Chemical Weathering on Basal Spacings of Clay Minerals

AbstractIllite, vermiculite, montmorillonite, kaolinite, and a Brookston soil clay were weathered by H‐, HO‐, and H‐resin; sodium tetraphenyl‐boron + resin; and boiling 1N nitric acid + resin treatments. X‐ray diffractograms of the treated clays suggest the following effects on the mineral structures. Resin caused relatively minor changes compared to unweathered specimens. NaBPh4 removed interlayer K from 10A and 10–14A interstratified components of illite, vermiculite, and Brookston soil clay resulting in partial expansion of 10–14A components as evidenced by diffractograms of glycolated samples. HNO3 dissolved less stable components of the illite specimen and/or favored preferred orientation of aggregates as indicated by marked increases in the intensity of mica basal reflections. Estimations of K content of mica from 10:5A peak‐intensity and area ratios indicated that mica remnants in acid‐treated illite were lower in K than those in unweathered or NaBPh4‐treated illite. Treatment with HNO3 severely altered the expansibility of vermiculite, transforming a part of the specimen into an expanding lattice structure and dissolving much of the remainder. The 10A and 14A components of Brookston soil clay were less altered by HNO3 treatment; however, the 17–18A peak in the glycolated sample was sharper, and thermally stable interlayer components were less evident after acid treatment. HNO3‐ and NaBPh4‐treated kaolinite and montmorillonite basal spacings remained essentially the same as untreated samples. These data are evaluated in terms of mechanisms of K‐release from the weathered clays and subsequent K‐content found in soybean plants (Glycine max L.) grown in the clay residues.

Nitric Acid Oxidation of Coal (II)

The properties of carboxyl groups in the oxidized coals obtained from Tenpoku-Fujita (C: 70.9%a.m.f.) and Sumiyoshi (C: 76.2%a.m.f.) coals by HNO3 treatment were studied by using the methods of ion exchange with Ca (CH3COO) 2 aq.sol.and infrared absorption spectra.Carboxyl groups in oxidized Fujita coals were subjected to Ca (CH3COO) 2 aq.sol.exchange completely under N2 atmosphere 18°C, 20hrs. While oxidized Sumiyoshi coals had later exchange rate than Fujita's, and yet exchange reaction proceeded after 7 days. But the exchange rate of the humic acid extracted from oxidized Sumiyoshi coal did not vary significantly from Fujita humic acid.These results were accessible by assuming a rate-determing diffusion of Ca++ ion into oxidized coals. In the case of treating the oxidized coals in much amount of Ca (CH3COO) 2 aq. sol., it could be seen that other acidic groups (probably phenolic) exchanged with Ca (CH3COO) 2. When the oxidized coals were heated in Ca (CH3COO) 2 aq. sol., a remarkable increase of exchange capacities was seen. These increase may be reduced to the action of CO2 given by decarboxylation and newly produced carboxyl groups.

Gaseous Nitrogen Losses from Nitrogen Fertilized Soils Measured With Infrared and Mass Spectroscopy

AbstractThe evolution of nitrogen gases from four soils was studied by total soil nitrogen analysis, the mass spectrometer with N15‐labeled nitrogen carriers, and with infrared spectroscopy. The type and amount of nitrogen gas evolved was influenced by a number of factors. Soil type was important in that the Nicollet and Fargo soils resulted in the evolution of more N2 and N2O than did the Fayette and Laredo soils. Soil properties had little effect on the total N2 evolved from NH4NO3, but greater differences occurred from soils treated with HNO3. The type of nitrogen carrier influenced the nature of the gaseous nitrogen released. NH4NO3 treatment favored N2O evolution and HNO3 treatment favored N2. Only small amounts of N2 and N2O were evolved from soils treated with NH4Cl or urea. Nitrogen applied at 1080 pounds per acre always resulted in larger losess of N2O and N2 than that applied at 360 pounds per acre. However, in both the Nicollet and Fargo soils at water saturation, the percentage of applied nitrogen that was lost was about the same at both low and high rates of treatment. Substantial gaseous losses of applied fertilizer occurred mainly when water‐saturated conditions prevailed. Small losses did occur from soils at field moisture capacity. N2O evolution was influenced by the ammonium to nitrate ratio of the nitrogen treatment.