Decomposition Conditions Research Articles

On Greenberg's generalized conjecture

For a number field F and an odd prime number p, let F˜ be the compositum of all Zp-extensions of F and Λ˜ the associated Iwasawa algebra. Let GS(F˜) be the Galois group over F˜ of the maximal extension which is unramified outside p-adic and infinite places. In this paper we study the Λ˜-module XS(−i)(F˜):=H1(GS(F˜),Zp(−i)) and its relationship with X(F˜(μp))(i−1)Δ, the Δ:=Gal(F˜(μp)/F˜)-invariant of the Galois group over F˜(μp) of the maximal abelian unramified pro-p-extension of F˜(μp). More precisely, we show that under a decomposition condition, the pseudo-nullity of the Λ˜-module X(F˜(μp))(i−1)Δ is implied by the existence of a Zpd-extension L with XS(−i)(L):=H1(GS(L),Zp(−i)) being without torsion over the Iwasawa algebra associated to L, and which contains a Zp-extension F∞ satisfying H2(GS(F∞),Qp/Zp(i))=0. As a consequence we obtain a sufficient condition for the validity of Greenberg's generalized conjecture when the integer i≡1mod[F(μp):F]. This existence is fulfilled for (p,i)-regular fields.

Cu/Fe Bimetallic Treatment Performance on Organophosphorus Pesticides

Typical organophosphorus pesticides, such as glyphosate, trichlorfon, and ethephon, are widely used nowadays, and the treatment of their production wastewater is difficult to achieve by conventional water treatment methods. A Cu/Fe bimetallic system has been proposed as a viable technology to treat toxic and refractory pollutants. The performance of the system with different pH, Cu/Fe molar ratios, Cu/Fe dosages, and initial glyphosate concentrations was analyzed to investigate the operational factors affecting glyphosate removal by the Cu/Fe bimetallic system. Acidic pH (2.0), 250 g/L Cu/Fe dosage, 0.25% Cu/Fe, and 60 mg/L initial glyphosate concentration were the appropriate conditions for glyphosate removal, in which the efficiency of the system was in accordance with the pseudo–second-order kinetic model. Under this condition, the removal efficiencies of total phosphorus and total organic carbon reached 99 and 65%, respectively. The Fe/Cu bimetal surface was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The optimal conditions for glyphosate decomposition were applied to the treatment of trichlorfon and ethephon. The removal efficiency of the system was poor, but its toxicity to luminescent bacteria Q67 was remarkably reduced.

Biocompatible hydroxyapatite nanoparticles as templates for the preparation of thin film polyelectrolyte multilayer nanocapsules

Thin films called polyelectrolyte multilayers could be formed by alternate adsorption of positively and negatively charged polyelectrolytes. In the case of adsorption on nanoparticles followed by the dissolution of the template, it is possible to prepare hollow polyelectrolyte capsules. Due to a large number of available polymeric compounds and easily tunable multilayer properties, these systems find their application in various fields such as biomedicine and catalysis. In this study we focused on the design, synthesis and characterization of capsules of nanometer dimensions made of nontoxic weak polyelectrolytes, poly(allylamine) and poly(acrylic acid) in a water medium using fully biocompatible hydroxyapatite nanoparticles as template. The formation of the polyelectrolyte multilayer was monitored by measuring the electrophoretic mobility of particles. After the optimization of the core decomposition conditions, hollow polyelectrolyte capsules were prepared by dissolution of the template in the presence of HCl. Further characterization was performed using Fourier-transform infrared spectroscopy, energy dispersion X-ray spectroscopy, dynamic light scattering, scanning electron microscopy, and atomic force microscopy. With these techniques, the chemical composition, structure, size, morphology and stability of obtained nanocapsules were determined. It was found that the capsules are of a rather narrow size distribution ranging from 100 to 250 nm with a flexible capsule wall being only a few tens of nanometers thick which is very important in the case of future applications in the field of drug delivery. Moreover, the dispersions of nanocapsules were stable for at least 40 days. This extreme stability of nanocapsules could be probably attributed to their low mass, small dimensions, and high surface charge.

Decomposition of hypercube graphs into paths and cycles of length four

By a -decomposition of a graph G, we mean a partition of the edge set of G into p paths of length 4 and q cycles of length 4. In this paper, we give conditions for a -decomposition of the n-dimensional hypercube graph Qn for all possible values of p and q. In particular, we find the necessary and sufficient conditions for such decomposition in Qn when n is even, and n is odd,

Recovery and Preparation of Potassium Fluorotantalate from High-Tantalum-Bearing Waste Slag by Pressure Alkaline Decomposition

Tantalum slag is a type of high-grade tantalum resource with great recovery value. In this paper, a low fluorine process, including alkali pressure decomposition, low-acid transformation, solvent extraction, and crystallization, is proposed to recover tantalum and prepare potassium fluotantalate. First, some tantalum slag underwent alkali pressure decomposition, and the optimal decomposition conditions were obtained under a reaction time of 2 h, oxygen partial pressure 2.5 MPa, liquid–solid ratio 4:1, basicity 40 wt.%, and temperature 200 °C. Under these conditions, the decomposition efficiencies of Ta and Nb were 93.62% and 95.42%, respectively. X-Ray diffraction (XRD) and scanning electron microscope (SEM) were used to detect the main phase of the decomposition residue and showed that it was mainly sodium tantalate. With the increase in oxygen partial pressure, the particle size of decomposition slag gradually decreases and becomes loose. Second, the alkali decomposition residue was subjected to low-acid leaching to obtain fluorine tantalate and fluorine niobate, and the leaching efficiencies of tantalum and niobium were more than 99%. Last, the low-acid leaching solution was subjected to solvent extraction and evaporative crystallization to prepare potassium fluotantalate. The results showed that the tantalum extraction rate and tantalum and niobium separation factors were above 94% and 200, respectively, and the purity of potassium fluotantalate met the requirements of commercial products. Compared with current industrial practice, the consumption of hydrofluoric acid was greatly reduced, and the recovery rate of tantalum was increased.

The Use of Products of Microwave Aminolytic Destruction of Polyethylene Terephthalate in Vibration-absorbing Polymer Composite Materials

The aim of this work is to study the possibility of using the products of aminolytic destruction of polyethylene terephthalate (PET) and their derivatives in polymer composite materials with vibration-absorbing properties, which provide effective damping of vibrations of technogenic and natural origin in a wide temperature and frequency range. The paper considers a modern method of recycling PET waste with a mixture of amino alcohols - monoethanolamine and triethanolamine, taken in two different ratios. As a result of the destruction reaction, terephthalic acid diamide (N, N -bis (2-hydroxyethyl) terephthalamide) is formed. To accelerate the destruction process, microwave radiation of various powers of 200, 540 and 700 watts was used. The optimal conditions for aminolytic decomposition of PET were determined: the time and power of microwave radiation with PET conversion up to 95% and the yield of the target product (terephthalic acid diamide) 80-85%. The destruction process was carried out according to a closed cycle of using reagents, without the use of catalysts and at atmospheric pressure, which to a certain extent reduces the energy consumption and increases the environmental friendliness of this method of PET decomposition. The aminolytic degradation product of PET (terephthalic acid diamide) was used as a monomer in the polycondensation reaction to obtain a new oligomer (terephthalic acid oligoesteramide). The degree of polymerisation (n) is in this case 7 to 11 (number of chain links). The obtained oligomer and the PET degradation product were investigated as new components in elastomeric compositions based on chloroprene rubber and in compositions based on thermoplastic elastomers. It has been demonstrated that the introduction of an oligomer based on a PET degradation product reduces the viscosity of elastomeric compositions by 25-35%. The study was supported by a grant from the Russian Science Foundation No. 21-79-00301, https://rscf.ru/project/21-79-00301/.

Dissipation and effect of glyphosate during composting of organic wastes.

The addition of organic matter (OM) containing glyphosate during compost production, through the introduction of contaminated plant residues or sewage sludge, presents a risk of hindering the proper OM breakdown carried out by microorganisms and causing the accumulation of glyphosate or aminomethylphosphonic acid (AMPA). To measure the effect of glyphosate and glyphosate-based herbicide (GBH) on OM decomposition as well as the dissipation of glyphosate to AMPA during composting, a controlled-environment experiment was conducted using mesocosm-scale vessels. Analytical-grade (AG) glyphosate (150mg kg-1 ) and GBH (VisionMAX) equivalent to the amounts applied in agricultural areas (300mg kg-1 ) were added to a mixture of green residues, which were then composted for 112 d. Sampling after 2, 7, 28, and 112 d showed a negligible effect of glyphosate and GBH on physicochemical properties of the mixture (temperature, OM%, pH, total carbon [C], total nitrogen [N], and C/N ratio), ammonification, nitrification, and phosphate content. No differences between AG glyphosate and GBH treatments were measured. Glyphosate levels decreased significantly after 2 d to reach 53.1 and 71.1% of the initial content for the AG glyphosate and GBH treatments, respectively, and glyphosate dissipation was almost complete after 112 d of composting. Aminomethylphosphonic acid could not be detected at any time during the experiment regardless of the treatment. Our results show that conditions for OM decomposition were maintained despite the addition of glyphosate and suggest that only trace amounts of glyphosate or AMPA are likely to be present in mature compost.

Designing Electrochemical Biosensing Platforms Using Layered Carbon-Stabilized Porous Silicon Nanostructures.

Porous silicon (pSi) is an established porous material that offers ample opportunities for biosensor design thanks to its tunable structure, versatile surface chemistry, and large surface area. Nonetheless, its potential for electrochemical sensing is relatively unexplored. This study investigates layered carbon-stabilized pSi nanostructures with site-specific functionalities as an electrochemical biosensor. A double-layer nanostructure combining a top hydrophilic layer of thermally carbonized pSi (TCpSi) and a bottom hydrophobic layer of thermally hydrocarbonized pSi (THCpSi) is prepared. The modified layers are formed in a stepwise process, involving first an electrochemical anodization step to generate a porous layer with precisely defined pore morphological features, followed by deposition of a thin thermally carbonized coating on the pore walls via temperature-controlled acetylene decomposition. The second layer is then generated beneath the first by following the same two-step process, but the acetylene decomposition conditions are adjusted to deposit a thermally hydrocarbonized coating. The double-layer platform features excellent electrochemical properties such as fast electron-transfer kinetics, which underpin the performance of a TCpSi-THCpSi voltammetric DNA sensor. The biosensor targets a 28-nucleotide single-stranded DNA sequence with a detection limit of 0.4 pM, two orders of magnitude lower than the values reported to date by any other pSi-based electrochemical DNA sensor.

Deep Prediction Model Based on Dual Decomposition with Entropy and Frequency Statistics for Nonstationary Time Series.

The prediction of time series is of great significance for rational planning and risk prevention. However, time series data in various natural and artificial systems are nonstationary and complex, which makes them difficult to predict. An improved deep prediction method is proposed herein based on the dual variational mode decomposition of a nonstationary time series. First, criteria were determined based on information entropy and frequency statistics to determine the quantity of components in the variational mode decomposition, including the number of subsequences and the conditions for dual decomposition. Second, a deep prediction model was built for the subsequences obtained after the dual decomposition. Third, a general framework was proposed to integrate the data decomposition and deep prediction models. The method was verified on practical time series data with some contrast methods. The results show that it performed better than single deep network and traditional decomposition methods. The proposed method can effectively extract the characteristics of a nonstationary time series and obtain reliable prediction results.

Experimental study and recognition of natural gas hydrate chemical reagent - CO2 exploitation

Abstract In order to solve the problems of slow replacement rate and low degree of substitution in the process of CO2 displacement by natural gas hydrate, a method of chemical reagent-CO2 displacement combined mining experiment was proposed. Taking the thermodynamic methanol inhibitor as an example, three groups of experiments were carried out: critical temperature pressure condition for CH4 decomposition at different methanol concentrations, CH4 hydrate decomposition under the condition of methanol reagent at 30% concentration, and methanol reagent-CO2 combined mining. Experiments show that: (1) The concentration of methanol plays a decisive role in hydrate recovery. Methanol reagent has the property of highly reducing the formation temperature of hydrate. Methanol solution concentration is positively correlated with the critical temperature drop of hydrate decomposition and formation pressure. (2) The methanol solution decomposition of hydrate can be roughly divided into three stages: the initial stage of rapid decomposition, the competitive stage of hydrate decomposition and stable transformation, and the stable stage of decomposition. Through experimental simulation, it is concluded that formation pressure is a direct factor affecting the decomposition ability of methanol reagent to hydrate. By changing formation pressure, the rate of CH4 hydrate recovery can be improved. (3) A higher hydrate decomposition rate can be obtained based on the methanol reagent-CO2 displacement mining method. In the action of the methanol reagent, the subsequent injection of CO2 still promotes the decomposition of CH4, that is, the displacement of CO2 hydrate after the decomposition of the hydrate based on the methanol reagent is feasible. The research results are of great significance especially for large-scale mine test mining of permafrost natural gas hydrate chemical reagent method.

Two‐step thermal decomposition mechanism of phosphogypsum for resource utilization

AbstractIn this work, the reduction–oxidation two‐step method was used for investigating the resource utilization of phosphogypsum. The influences of different decomposition conditions were investigated, including the reducing process and oxidizing process. The reductive organic sulphide in lignite reacted with CaSO4 and improved the CaSO4 decomposition rate. High Fe2(SO4)3 content and anhydrous air flow rate promoted the formation of Fe–Ca–Ox, decreasing the CaSO4 decomposition rate. H2O derived from CH4 reacted with lignite to consume the solid reducing agent. In the reducing process, CaSO4 reacted with CH4 and lignite to form CO, CO2, H2O, and CaS. In the oxidizing process, CaS was mainly oxidized into CaO, SO2, and element S. Through a two‐step decomposition process (reduction with CH4 and oxidation with air), the decomposition temperature of phosphogypsum decreases and the decomposition efficiency is improved. Meanwhile, the residual lignite was oxidized into CO and CO2. Therefore, it is meaningful and valuable.

Hydrate decomposition front within porous media under thermal stimulation and depressurization conditions: Macroscale to microscale

Natural gas hydrates are unstable and easily to be decomposed under warming or depressurizing condition. The complicated hydrate decomposition process is generally characterized by a moving decomposition front, yet the essence of decomposition front evolution is unclear and the evidence is lacking. In this study, X-ray computed tomography (X-CT) technology is used to reveal the dynamic process of macroscale and microscale evolution of hydrate decomposition front. The hydrate-bearing porous samples are synthesized in the high-pressure reactor and then decomposed by the thermal stimulation method and the depressurization method with X-CT scans in real time. Macroscale results show that isolated hydrates beyond the decomposition front remain undecomposed under both two decomposition conditions, indicating the oversimplification of the decomposition front as the boundary where gas hydrates are completely decomposed. Hence, the decomposition front is redefined as the boundary which divides the hydrate-bearing sediment into an interconnected zone and an isolated zone based on the interconnectivity of hydrate particles. Microscale hydrate decomposition behaviors show that, the heat transfer differences among pores, solid media, and gas hydrates under thermal stimulation condition result in the remnant of isolated hydrates beyond the outside-in moving decomposition front. The gas fugacity differences in gas phase, water layer, and dead-end pores under depressurization condition result in the remnant of isolated hydrates beyond the top-down moving decomposition front. More importantly, we found that the remnant grain-cementing hydrates could alter the thermal- hydro-mechanical-chemical (THMC) processes outside the decomposition front, and play important roles in formation stability and ecological environment by supporting the skeleton structure of hydrate-bearing sediments. These findings may provide implications and visual evidences for production efficiency improvement and environmental protection in future field tests of hydrate exploitation.

Catalytic Pyrolysis of High-Density Polyethylene: Decomposition Efficiency and Kinetics

Organic waste is generally characterized by high volume-to-weight ratios, requiring implementation of waste minimization processes. In the present study, the decomposition of high-density polyethylene (HDPE), was studied under thermal and catalytic pyrolysis conditions on two experimental systems. Firstly, pyrolytic conditions for HDPE decomposition were optimized in a laboratory-scale batch reactor. In order to maximize gas yields and minimize secondary waste, the effects of aluminosilicate catalysts, catalyst loading, and reaction temperature on decomposition efficiency were examined. Secondly, kinetics and reaction temperatures were studied on a large capacity thermobalance, especially adjusted to perform experiments under pyrolytic conditions at a larger scale (up to 20 g). The addition of catalysts was shown to enhance polymer decomposition, demonstrated by higher gas conversions. Condensable yields could be further minimized by increasing the catalyst to polymer ratio from 0.1 to 0.2. The most prominent reduction in pyrolysis temperature was obtained over ZSM-5 catalysts with low Si/Al ratios; however, this impact was accompanied by a slower reaction rate. Of the zeolites tested, the ZSM-5 catalyst with a Si/Al of 25 was found to be the most efficient catalyst for waste minimization and organic destruction, leading to high gas conversions (~90 wt%.) and a 30-fold reduction in solid waste mass.

Decomposition of Fourth-Order Euler-Type Linear Time-Varying Differential System into Cascaded Two Second-Order Euler Commutative Pairs

This paper presents decomposition of the fourth-order Euler-type linear time-varying system (LTVS) as a commutative pair of two second-order Euler-type systems. All necessary and sufficient conditions for the decomposition are deployed to investigate the commutativity, sensitivity, and the effect of disturbance on the fourth-order LTVS. Some systems are commutative, and some are not commutative, while some are commutative under certain conditions. Based on this fact, the commutativity of fourth-order Euler-type LTVS is investigated by introducing the commutative requirements, theories, and conditions. The fourth-order Euler-type LTVSs are investigated into commutative pairs of twice Euler-type second-order linear time-varying systems (LTVSs). The decomposition theories and conditions are derived, proved, and solved to simplify the use of commutativity for practical and industrial uses. Some fourth-order systems are sensitive toward change in initial conditions or parameters while others are not, and the effect due to disturbance also varies within systems. Furthermore, the stability and robustness of systems have so many issues. But we consider fourth-order Euler-type LTVS to observe, investigate, and tackle these issues. Lastly, the realization of fourth-order LTVS from cascaded two second-order systems can be laboratory experimented which is an open problem for future engineers to investigate. However, the theoretical results show a good agreement with the simulation results is considered in this work. Perhaps it might have unlimited physical applications in science and engineering as well as theoretical contribution. But beyond any reasonable doubt, the novelty is guaranteed because this study is the first of its kind that introduces the decomposition of the fourth-order Euler-type linear time-varying system (LTVS) as a commutative pair of two second-order Euler-type systems. Illustrative examples are presented to support the results.

Efficient extraction of tungsten from scheelite with phosphate and fluoride

Considering the problems of high temperature and large reagent consumption in the current alkali decomposition processes, phosphate and fluoride were adopted to extract tungsten from scheelite. The results indicated that tungsten could be efficiently extracted with a decomposition rate of> 98.0% under moderate decomposition conditions, forming fluorapatite in the decomposition residue. The decomposition yield is influenced by the calcium fluoride dosage, decomposition temperature, liquid-to-solid ratio, and holding time. Furthermore, the decomposition reaction followed the surface chemical reaction controlling step. Additionally, the phosphorus concentration in the decomposition solution was lower than 0.2 g/L. This work may provide an alternative for the efficient tungsten extraction from scheelite, especially fluorite bearing scheelite under relatively low reagent costs and temperature.

Assessing the potential of a Trichoderma-based compost activator to hasten the decomposition of incorporated rice straw

The potential for a Trichoderma-based compost activator was tested for in-situ rice straw decomposition, under both laboratory and field conditions. Inoculation of Trichoderma caused a 50% reduction in the indigenous fungal population after 2 weeks of incubation for both laboratory and field experiments. However, the Trichoderma population declined during the latter part of the incubation. Despite the significant reduction in fungal population during the first 2 weeks of incubation, inoculated samples were found to have higher indigenous and total fungal population at the end of the experiments with as much as a 300% increase in the laboratory experiment and 50% during day-21 and day-28 samplings in the field experiment. The laboratory incubation experiment revealed that inoculated samples released an average of 16% higher amounts of CO2 compared to uninoculated straw in sterile soil samples. Unsterile soil inoculated with Trichoderma released the highest amount of CO2 in the laboratory experiment. In the field experiment, improved decomposition was observed in samples inoculated with Trichoderma and placed below ground (WTBG). From the initial value of around 35%, the C content in WTBG was down to 28.63% after 42 days of incubation and was the lowest among treatments. This is significantly lower compared with NTBG (No Trichoderma placed below ground, 31.1% C), WTSS (With Trichoderma placed on soil surface, 33.83% C), and NTSS (No Trichoderma placed on soil surface, 34.30% carbon). The WTBG treatment also had the highest N content of 1.1%. The C:N ratio of WTBG was only 26.27, 39.51% lower than the C:N ratio of NTBG, which is 43.43. These results prove that the Trichoderma-based inoculant has the potential to hasten the decomposition of incorporated rice straw.

An inverse problem in an elastic domain with a crack : a fictitious domain approach

An inverse problem applied to volcanology is studied. It consists in the determination of the variable pressure applied to a crack in order to fit observed ground displacements. The deformation of the volcano is assumed to be governed by linear elasticity. The direct problem is solved via a fictitious domain method, using a finite element discretization of XFEM type. The ground misfit is minimized using a combination of a domain decomposition and optimatily conditions. The gradient of the cost function is derived from a sensitivity analysis. Discretization of the problem is studied. Numerical tests (in 2D and 3D) are presented to illustrate the effectiveness of the proposed approach. In particular, we find that a quasi-Newton method is more efficient than a conjugate gradient method for solving the optimization problem.

СТРАТЕГІЧНО-ОРІЄНТОВАНЕ УПРАВЛІННЯ ПРОЄКТАМИ ЛОГІСТИЧНОГО АУТСОРСИНГУ В ДИНАМІЧНОМУ ЗОВНІШНЬОМУ СЕРЕДОВИЩІ

The actuality of the research topic is due to the need to improve and further develop the methodological support of strategic-oriented project management in organizations in terms of interrelated representation of processes at the stages of formulation (formation) and implementation of organizational strategy in the context of functioning and development in a dynamic and / or relatively complex environment. . The purpose of the study is to increase the effectiveness of strategic-oriented project management in a dynamic environment by developing the concept of project-oriented management of interrelated processes at the stages of formation and implementation of organizational strategy of logistics outsourcing - as an evolving strategy. Objectives of the study: to analyze the methods, models, mechanisms and standards of project management on the issues of strategic-oriented project management in the organization; propose a concept of management of the formation and implementation of organizational strategy of logistics outsourcing using a project approach; to develop an approach to the formation of the typology of projects for the development of organizational strategy of logistics outsourcing (DOSLO) with the definition of the relevant conceptual framework; to separate, according to the conditions of structural decomposition, delivery objects for the products of the selected categories of DOSLO projects; to develop a model of management of the use of logistics assets in projects to test the change of the DOSLO phase. Utilized techniques of the research. Based on the assumption supported by descriptive scientific schools in strategic management, as well as following the concept of "evolving strategy", it was concluded that organizational strategy can be presented as a sequence of potentially basic phases of development, the transition between which and changes are treated as an experiment organizations. At the same time to avoid, or at least significantly reduce the likelihood, the occurrence of the problem of "loss of strategy" - has the implementation of these experiments in the form of projects.

Diffuse nutrient export dynamics from accumulated litterfall in forested watersheds with remote sensing data coupled model

Nutrients exported from forest litterfall significantly contribute to the global cycling of elements and the water quality in watersheds. Simulating the watershed discharge load is challenging because of the combined effects of the decomposing litterfall and topographic heterogeneity. We quantified the contribution of diffuse nutrient export from forest litterfall in a low temperature watershed using artificial rainfall experiments and watershed territorial modeling with remote sensing data, and therefore, the critical spatial factors and corresponding nutrient export dynamics were identified. Rainfall intensity and terrain slope were found to be the key factors for nutrient export under different litterfall decomposition conditions. Based on the moderate resolution imaging spectroradiometer data and field observations, the temporal patterns of litterfall biomass of two types of dominant forests (broad-leaved and mixed) were interpreted. The spatial patterns of total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) exports from watershed litterfall were simulated by coupling the observed discharge parameters under artificial rainfall conditions and watershed surface flow modeling with the hydrological characteristics of the forested areas. The average watershed TOC, TN, and TP loads exported from the litterfall were approximately 58.22, 7.89, and 0.37 kg ha−1 a−1, respectively. The exported loads of TOC, TN, and TP varied with the forest types, and the loads from the litterfall of deciduous broad-leaved forest were found to be ∼50–70% of loads from the litterfall of mixed forest. A comparison with similar studies worldwide also indicated that low temperature decreased the litterfall decomposition rate and diffuse nutrient export. This study indicated that litterfall nutrients were a key contributor to watershed water pollution, and their spatial discharge trend varied intensively with the terrestrial conditions. The modified simulation methods were found to accurately assess the cycling of nutrients from the forest litterfall on a watershed scale.

Simple superphosphate by two-stage acid treatment of phosphate raw materials

The distinguishing feature of the proposed flow method before the classical (chamber) method is that the entire production cycle of natural phosphate processing is carried out in two stages. At the first stage, the phosphorite is treated with a stoichiometric flow rate of concentrated sulphuric acid (at least 93%), under conditions of complete decomposition of phosphorite to form phosphoric acid and crystals of anhydrite (calcium sulfate). The reaction temperature is 122 °C. In the second stage, the resulting concentrated solution of phosphoric acid in a mixture with sulphur is involved in a reaction with an additional input of phosphorite, which is the basis for the mechanism of chemical formation of monocalciumphosphate and granulation of superphosphate mass. The processes for neutralizing phosphoric acid on monocalciumphosphate and for granulating the product by coagulation are combined in one apparatus. The drying stage of the product is excluded from the scheme.