Photocatalytic oxidation of aqueous ammonia over microwave-induced titanate nanotubes

Characterizations of microwave-induced titanate nanotubes (NaxH(2-x)Ti3O7, TNTs) were conducted by the determinations of specific surface area (S(BET)), X-ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS), ionic coupled plasma-atomic emission spectrometry(ICP-AES), scanning electron microscopy/ energy dispersive X-ray (SEM/EDX), and high-resolution transmission electron microscopy (HR-TEM). The applied level of microwave irradiation during the fabrication process is responsible for both the intercalation intensity of Na atoms into TNTs and the type of crystallization phase within TNTs, which dominate the efficiency of photocatalytic NH3/NH4+. A pure TNT phase presents no powerful ability toward photocatalytic NH3/ NH4+, while the photocatalytic efficiency can be enhanced with the presence of a rutile phase within TNTs. In addition, the mixture of anatase and rutile phase within P25 TiO2 prefers forming NO3-, whereas TNTs yield higher NO2- amount Regarding the effect of acid-washing treatment on TNTs, the acid-treated TNTs with enhanced ion exchangeability considerably improve the NH3/NH4+ degradation and NO2-/NO3- yields. This result is likely ascribed to the easy intercalation of NH3/ NH4+ into the structure of acid-washing TNTs so that the photocatalytic oxidation of intercalated NH3/NH4+ is not limited to the shielding effect resulting from the overload of TNTs.     

The effects of injecting nitrapyrin (‘N-serve’), carbon disulphide or trithiocarbonates,with aqueous ammonia,on yield and %N of grass

Nitrapyrin and carbon disulphide (CS₂), or sodium or ammonium trithiocarbonate (which evolve CS₂ in soil), were injected with aqueous ammonia (NH₃) into grassland in three successive seasons at Rothamsted and at Woburn, using a new site each season. Injection was done either in November (‘autumn’), or in the following February or March (‘spring’). When applied in autumn, the inhibitors increased yield and %N of grass after the mild, wet winter of 1974-75, but had little or no effect in the two subsequent seasons. These effects are consistent with rates of nitrification of the injected NH₃, estimated by KC1 extraction of soil taken from injection slits, and with winter rainfall. When inhibitors were applied in spring, yields were consistently improved at Rothamsted but depressed at Woburn. All effects were small. Nitrapyrin or CS₂, injected with aqueous NH₃ into grassland in autumn, reduces nitrogen losses that occur in winter. However, judging from grass yields, in these experiments (in south-east England) losses were only a small fraction of the dose of N applied. Injecting these inhibitors with NH₃ in spring can delay nitrification and increase the persistence of the injected N, but this will not necessarily increase yield.     

Mineral balance in grass as influenced by fertility conditions in soil

Studies on the mineral balance in paragrass, Brachiaria mutica (Forsk.) Stapf, showed that the K/(Ca+Mg) ratio only once exceeded 1.80 under different fertiliser treatments; this was taken to be due to a relatively high Mg content in the plant tissue. Fertiliser N decreased the K/(Ca+ Mg), K/Mg, and K/Ca ratios in the grass, and the percentage of nitrogen in the tissue was negatively correlated with the K/(Ca+Mg) ratio.     

Mechanism and kinetics of the catalytic oxidation of aqueous ammonia to molecular nitrogen

Aqueous phase catalytic oxidation of ammonia has been studied over Ru/TiO2 catalyst in a batch reactor by changing the solution pH, concentration of catalyst in the solution, temperature, and reaction time. The oxidation reaction of ammonia over Ru/TiO2 catalyst has been found to take place exclusively for the aqueous NH3 with a preferred mode in strong alkaline pH region. An oxidation reaction pathway has been proposed as follows: Oxidation of ammonia is initiated by the reaction of aqueous ammonia with catalytically activated oxygen. After undergoing further successive oxidation reactions with activated oxygen, ammonia is finally oxidized to a molecule of nitrous acid. Nitrous acid dissociates into a nitrite ion and a proton. The solution pH is decreased with the protons from the dissociation of HNO2 so that the solution concentration of NH4+ is increased. Molecular nitrogen as a final product is produced from the homogeneous aqueous phase reaction between nitrous ion and ammonium ion. Further reaction of nitrous ion with the activated oxygen leads to the formation of nitrate ion. The reaction pathway proposed has been validated with the changes of solution pH along with the ammonia conversions, and the formation of N2 from the solution containing NO2- and NH4+ ions in equimolar amounts of nitrogen has been confirmed in a separate experiment. The kinetics of aqueous ammonia oxidation reaction has been well represented as a first-order reaction with respect to the concentration of aqueous ammonia, and an apparent rate constant has been obtained as a function of catalyst concentration in solution, oxygen pressure, and reaction temperature.     

In situ degradability of fresh grass and grass conserved under different harvesting methods.

The effects of forage conservation and harvesting method on DM and CP degradability of grass cut at the boot stage were determined using nylon bags incubated in the rumen of two fistulated lactating cows. Samples of fresh grass, wilted grass prior to and after ensiling in a stack silo and cut with either a cylinder-type forage harvester (11.3 mm of length cut) or a self-loading wagon (42.4 mm of length cut), wilted grass prior to and after ensiling in large round bales, and grass hay were obtained from the same field and used for determination of DM and CP degradability. The DM-soluble fraction of fresh grass was significantly lower than that of wilted grass and silage, but it was higher than that of hay. In general, the potentially degradable fraction of all treatments was related inversely to the readily soluble fraction in water. The effective degradability of DM of fresh grass was similar to that of hay but was lower than that of wilted grass and silage. The effective degradability of DM of silage was higher than that of wilted grass and hay. The disappearance rate of CP of fresh grass was similar to that of wilted grass, hay, and silage. Silage had a lower disappearance rate of CP than wilted grass. The effective degradability of CP was similar for fresh and wilted grasses. Protein degradability was greater for silages than for fresh and wilted grasses. Protein degradability of hay was similar to that of fresh grass and wilted grass.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of long periods under grass on soils under british conditions

The effects of long periods (up to many centuries) under grass on 34 mineral soils have been studied by contrasting their physical and other characteristics with the same soils which had a predominantly arable history in living memory. The old grassland soils contain more organic matter (as measured by total nitrogen), more total pore space, aggregates of greater water-stability, hold more water both at the sticky point and the lower plastic limit, contain more worms but have a smaller bulk (or apparent) density. A highly significant (P = 0.7%) correlation was shown between the nitrogen level and the clay content of the old grassland soils. A significant (P = 1.5%) correlation was found between the water-stability of the old grassland soil aggregates and their clay content but not with the nitrogen level (P = 5.3%).     

Effect of aqueous ammonia and other alkalis on the in-vitro digestibility of barley straw

The in-vitro digestibility of the organic matter of unground barley straw was increased by approximately 14 units by treatment with aqueous ammonia for 1 week at 20°C. Longer treatment times of 4 and 13 weeks had little or no additional effect on digestibility. Treatment with sodium hydroxide or tetramethylammonium hydroxide increased digestibility by up to 22 units. The content of cell walls of the straw after treatment with any of the alkalis was lower than that of untreated straw and the degradability of the walls from alkali-treated straw was more than 85% greater than that of the walls from untreated straw. Alkali treatment of straw caused loss of p-coumaric, ferulic and diferulic acids from the cell walls, the loss being greater with the stronger alkalis. The loss of ferulic was greater than that of p-coumaric acid.     

An investigation of analytical procedures for predicting soil nitrogen supply to grass in the field

Procedures based on five methods of soil analysis for predicting potentially mineralisable N, and hence soil N supply, have been evaluated and compared with prediction based on total soil N. The effect of adjusting the analytical results for differences in soil temperature and water status between sites has also been examined. The evaluation was performed by calculating the extent to which the results accounted for variation in the amounts of N in the herbage of perennial ryegrass plots receiving no fertiliser N. The plots were situated at 18 sites throughout the UK: at some sites results were available for more than 1 year, giving a total of 29 site/years. The best prediction, accounting for 65 % of the variation in herbage N yield, was obtained when the amounts of ?glucose’? extracted from the soils by 0.05M Ba(OH)₂ were combined with the amounts of NO₃-N extracted by 2M KC1, and the combined values adjusted for soil temperature and water status. A procedure based on the measurement of the NH₄-N released by autoclaving the soils with 0.01M CaCL₂ accounted for 51 % of the variation However, procedures based on (a) NH₄-N extracted by acid KMnO₄, (b) non-NO₃-N extracted by 0.01M NaHCO₃, and on (c) measurement of the absorbance at 260 nm of NaHCO₃ extracts, were no more effective than was analysis for total soil N (less than 36% of the variation accounted for when values were adjusted for soil temperature and water status).     

Chiral signatures show volatilization from soil contributes to polychlorinated biphenyls in grass

Enantiomer fractions (EFs) of PCB 95 and concentrations of PCBs 28/31, 52, 101, 118, 138, 153, and 180 were determined in air. Samples were taken at ~14 day intervals on a vertical gradient at an urban background site in Birmingham U.K. in summer 2009 (114 days) and spring 2010 (84 days). EFs in air at 3 cm height were nonracemic (average 0.453 (2009) and 0.468 (2010)) and differed significantly (p < 0.05) from the racemic EFs in air at 10, 40, 90, and 130 cm. EFs in soil (average 0.452 (2009) and 0.447 (2010)) closely matched those in air at 3 cm, while those in grass (average 0.468 (2009) and 0.484 (2010)) were intermediate between those in soil and the racemic EFs in air at ≥ 10 cm. This implies that at the study site, PCBs volatilize from soil to an extent discernible only at the soil:air interface, and that PCBs in grass arise due to foliar uptake of volatile emissions from soil. Atmospheric concentrations of ΣPCBs increased significantly (p < 0.05) with increasing height. Combined with the chiral signature data, this suggests the influence of PCB emissions from soil on airborne concentrations decreases with altitude, while that of emissions from the built environment increases.     

Mitigation of ammonia and hydrogen sulfide emissions by stable aqueous foam-microbial media

Stable aqueous foam-microbial media consisting of protein-based foams and odor-degrading bacteria were developed to control the emissions of odorous compounds. The optimum foam formulation was determined based on foam characteristics including 50% drainage time, foam lifetime, and foam expansion ratio. When only the aqueous foam was applied onto the surface of a test odor source (i.e., swine manure), ammonia emission was completely suppressed for about 177, 225, 265, 297, and 471 min when the height of foam barrier was 2.5, 5, 10, 15, and 30 cm, respectively. According to the increasing foam height, ammonia emission rates after breakthrough points decreased to 0.16, 0.13, 0.09, 0.07, and 0.02 mg/m3/min, and thus volatilized ammonia concentrations decreased significantly after 600 min. Hydrogen sulfide was similarly suppressed. Ammonia emission was better controlled by incorporating odor-degrading bacteria into the aqueous foam. The odor suppression capacity of the 5-cm foam barrier with microbes was more than eight times greater than that of the barrier only and was similar to that of 30-cm foam barrier without microbes after 1440 min. A significant amount of dinitrogen gas was evolved by the foam-microbial media, indicating a successful biological transformation of ammonia.     

The determination of particle size distribution in soil. A collaborative study

A collaborative trial on the determination of particle size distribution in soil is described. The analytical method used was that of Avery and Bascombe. Twelve laboratories participated, all of which had considerable experience of the method. Eight soils were collected, divided and distributed by one of the laboratories. The variation in the results is due to errors arising both from the sampling technique and from the analytical method. Estimates of the within and between laboratories variation for the values found in each particle size class for the eight soils are given. Those analyses with high loss are found to give, on average, almost the same particle size distribution as those with low loss.     

水温差阶段漂洗对草鱼鱼糜凝胶品质的影响

以草鱼鱼糜凝胶为研究对象,从凝胶白度、凝胶强度、TPA质地特性(硬度、压缩功、回复性、可恢复形变、内聚性、咀嚼性)以及凝胶析水率几方面研究了新型鱼糜漂洗方式——水温差阶段漂洗对草鱼鱼糜凝胶品质的影响,结果表明:水温差阶段漂洗可显著提高草鱼鱼糜凝胶的白度和凝胶强度,改善草鱼鱼糜凝胶的质构特性,提高鱼糜凝胶的保水能力。由此可知,水温差阶段漂洗是一种简便、有效的鱼糜漂洗方法。     

Uptake and distribution of iodine in grass and clover plants grown in solution culture

Perennial ryegrass (S23), timothy (S48), white clover (S100) and red clover (Hungaropoly), grown in culture solutions containing 0.2 × 10^?7, 1.0 × 10^?7, 5.0 × 10^?7 and 1.0 × 10^?6 M -potassium iodide, showed relatively small differences in iodine uptake. The lowest uptake occurred with timothy, the species that also produced the lowest yields of dry matter. Red clover had the lowest concentration of iodine in the shoots on all treatments, its difference from the other species being proportionately greater at the higher levels of iodide supply. The transport of iodine from roots to shoots was restricted in all species, with roots having much greater concentrations of iodine than shoots. However, with the exception of red clover, transport to the shoots increased considerably as the supply of iodide was increased. Two diploid and two tetraploid varieties of red clover also showed only small differences in uptake and concentration of iodine in their shoots and roots, although the tetraploid varieties did have somewhat lower concentrations in their shoots at the lowest level of iodide supply. Plants of perennial ryegrass and red clover grown for eight weeks on solutions containing 1.0 × 10^?7 M -iodide had higher concentrations of iodine in dead and senescent leaves than in green shoot material. Iodide was taken up much more readily than iodate, and chloride, even at concentrations up to 50000 times the iodide concentration, did not depress the uptake of iodide.     

Dissolution of various sources of gypsum in aqueous solutions and in soil

The dissolution of six sources of gypsum in water and 0.01 M CaCl₂ was examined in the presence and absence of soil. The gypsum samples included: analytical grade (AR), three sources of flue-gas desulphurisation (FGD) gypsum, phosphogypsum (PG), and mined gypsum (MG). Dissolution in aqueous solutions was monitored by measuring the concentration of calcium (Ca²⁺) and sulphate (SO) ions. In soils which adsorb small amounts of SO^?2₄, dissolution was estimated from the increase in the concentration of Ca²⁺ and SO in gypsum-treated soil over the control soil. However, in soils which adsorb significant amounts of SO, measurement of solution SO concentration underestimates the extent of dissolution. Gypsum dissolution was larger in water (15.20 mmol litre^?1) than in 0.01 M CaCl₂ (11.12 mmol litre^?1), and this was attributed to the Ca²⁺ common-ion effect. The rate of dissolution decreased in the order: AR > FGD > PG > MG. Dissolution was 2 to 10 times faster for powdered (< 500 .m) gypsum than for the discs obtained by pelletising. The differences in the rate of dissolution between the gypsum sources and between powder and disc samples were related to both surface area and the presence of CaCO₃, impurity. The rate of dissolution was 3 to 8 times faster in the presence than in the absence of soil. Whereas the dissolution of gypsum in the presence of soil followed first order reaction kinetics, it followed second order kinetics in the absence of soil. This difference in reaction kinetics resulted from the continuous removal of Ca2+ and SO by the soil.     

Effect of thawing rate on distribution of an injected salt and phosphate brine in beef

Striping or streaking is a problem in moisture enhanced meats which are injected to low levels. Research was undertaken to determine brine distribution paths and effect of pre-injection thawing rate on brine distribution. Beef rib eyes and eye of rounds were vacuum packed and aged 7 days at 3°C, then frozen (-35°C) for a month, thawed either quickly in water (5h at 12-17°C) or slowly in air (48h at 3°C), injected to 108-110% using a conventional brine containing blue food colouring, chilled overnight, then cut along four planes and photographed for image analysis of % blue, % marbling, and subjective evaluation of brine distribution paths. There were no significant differences in % blue due to treatment. Brine distribution in both muscles was better parallel to fibers than perpendicular to them. A subset of aged rib eyes was injected to 125%. Although brine was more extensively distributed than at lower injection levels, basic patterns remained unchanged.     

Effects of pH and catalyst concentration on photocatalytic oxidation of aqueous ammonia and nitrite in titanium dioxide suspensions

Batch experiments were conducted to study the effects of titanium dioxide (TiO2) concentration and pH on the initial rates of photocatalytic oxidation of aqueous ammonium/ ammonia (NH4+/NH3) and nitrite (NO2-) in UV-illuminated TiO2 suspensions. While no simple kinetic model could fit the data at lower TiO2 concentrations, at TiO2 concentrations > or = 1 g/L, the experimental data were consistent with a model assuming consecutive first-order transformation of NH4+/NH3 to NO2- and NO2- to nitrate (NO3-). For TiO2 concentrations > or = 1 g/L, the rate constants for NO2 photocatalytic oxidation to NO3 were far more dependent on TiO2 concentration than were those for NH4+/NH3 oxidation to NO2-, suggesting that, without sufficient TiO2, complete oxidation of NH4+/NH3 to NO3- will not occur. Initial NH4+/NH3 photocatalytic oxidation rates were proportional to the initial concentrations of neutral NH3 and not total NH3(i.e., [NH4+] + [NH3]). Thus, the pH-dependent equilibrium between NH4+ and NH3, and not the pH-dependent electrostatic attraction between NH4+ and the TiO2 surface, is responsible for the increase in rates of NH4+/NH3 photocatalytic oxidation with increasing pH. Electrostatic adsorption, however, can partly explain the pH dependence of the initial rates of NO2- photocatalytic oxidation. Initial rates of NO2- photocatalytic oxidation were 1 order of magnitude higher for NO2- versus NH4+/NH3, indicating thatthe rate of NH4+/NH3 photocatalytic oxidation to NO3- was limited by NH4+/NH3 oxidation to NO2- under our experimental conditions.     

Effects of gamma irradiation on the distribution of calcium ions in grass shrimp (Phenaeus monodon F.) muscle

Effects of medium-dose (5 kGy) irradiation on the calcium ion distribution in shrimp muscle were studied using an electron microprobe (EDX) and an electron microscope. In irradiated shrimp muscle cells, the calcium ions in the sarcoplasmic reticulum and nuclei were not released to the myofibrils, and remained in situ during 8 days storage at 4°C after irradiation. However, without irradiation the concentration of calcium ions in the myofibrils of muscle cells increased after the same storage period. The distribution of calcium ions could play a role in the softening of shrimp meat, induced by proteinase.