Processes and Factors Affecting Phosphorus Sorption in Soils

The subject of this chapter is soil chemistry. The chapter is entitled Processes and Factors Affecting Phosphorus (P) Adsorption in Soils. The chapter aims to give an overview of the major mechanisms responsible for phosphate sorption (i.e., adsorption and absorption of phosphate) in soils, particularly of acid soils. According to studies conducted by some soil scientists, the major soil factors affecting P sorption are time, soil pH, soil organic matter, and iron and aluminium oxides of soils. Studies conducted indicated that adsorption of the P increases as the P ages in the soil. Soil pH affects phosphate adsorption but the effect is limited for adsorption by soils in the pH range of 4–8. Organic matter may affect P adsorption in two ways: indirectly by inhibiting iron oxide crystallisation and directly by competing for adsorption sites. On per mole basis, oxalate extractable aluminium oxides adsorb nearly twice as much P as oxalate extractable iron oxides due to poorer crystallinity (higher specific area) of the aluminium oxides compared to the iron oxides and also to a higher charge of the former. The chapter also highlights the pedotransfer functions (PTFs) of Borggaard, which can be used to calculate for the P adsorption in highly weathered acid soils

Pretreatment And Fractionation Of Biomass For Biological Production Of Transportation Fuels And Value Added Chemicals

Lignocellulosic biomass is an abundant renewable material from hardwood, softwood, grasses and agricultural residues for ethanol production. Pretreatment of lignocellulosic materials has been a main technical challenge to a cellulosic ethanol production process. The purpose of this thesis is to investigate four pretreatment methods and conduct comparative analyses among pretreatment methods, chemicals used and biomass species to determine the best process in terms of glucan to ethanol conversion efficiencies

Asymmetric Effects in Geopolitical Risk and Foreign Reserves Accumulation Among BRICS Countries

Over the past decade, the rise of Geopolitical Risk (GPR) has had a significant effect on macro financial variables, prompting central banks to accumulate reserves as a war chest to protect their economies from the detrimental effects of such shocks. This study examines the asymmetries in the long run, short run, and locational asymmetric effects on foreign reserves in the BRICS countries, using both the Nonlinear ARDL (NARDL) and Quantile ARDL (QARDL) models over the period 2000Q1–2021Q4. The results of the NARDL model suggest that GPR has long-run asymmetric effects for BRICS, while in the short run, all countries display insignificant asymmetries. The QARDL model reveals a quantile-dependent asymmetric relationship both in the long run and short run in the BRICS countries. In the long run, GPR has a significant impact on reserves at the higher quantile for Brazil, lower quantiles for China and South Africa, and had an insignificant impact in Russia and India. In the short run, GPR impacts are located at the lower quantiles in South Africa. The control variables of Real Effective Exchange Rate, M2 Money, Foreign Direct Investment, and Domestic Credit to Private Sector have asymmetric effects on reserves at extreme quantiles both in the long run and short run. Central bankers are advised to consider geopolitical risk when accumulating foreign exchange reserves for precautionary reasons

Water Sorption Isotherm Characteristics of Seeds of Six Indigenous Forest Tree Species in Ghana

The relationship between storage temperature, relative humidity and seed water content was investigated for six indigenous forest tree seed species, namely Garcinia kola, Terminalia superba, Terminalia ivorensis, Mansonia altissima, Entandrophragma angolense and Khaya anthotheca in Ghana. Seeds were equilibrated over a series of lithium chloride solutions with relative humidities ranging from 12 to 93% and silica gel with relative humidity of 3% at 20 ºC. Seeds reached equilibrium with different days depending on seed size and structure, ranging from 13 days for E. angolense to 91 days for G. kola. When seeds equilibrated, moisture contents were determined gravimetrically, and values of moisture contents were then plotted against relative humidity to construct moisture sorption isotherms for the species. Seeds of T. superba, T. ivorensis, M. altissima, E. angolense and K. anthotheca, exhibited a sigmoidal relationship between seed water content and relative humidity indicative of three regions of water binding. Contrarily to other reports, the shape of the isotherm curve for G. kola – a desiccation sensitive species – also showed the reversed sigmoid pattern similar to isotherm curves of orthodox species rather than the monotonic shape. The isotherms showed that seed moisture content increased with increasing relative humidity. Seed samples of G. kola, placed at all relative humidities chambers, lost water(desorption) as the initial water content of 58% was very high and, therefore, possessed a higher water potential than the environments. Seeds of the other species either lost water (desorption) to the relative humidity chambers, or absorbed water from the chambers depending on the relative humidity of the environment they were placed

Phosphate rock dissolution and availability in some soils of semi-deciduous Rainforest Zone of Ghana

Alfisols and Ultisols of the semi-deciduous forest zone of Ghana are known to be moderately acid and very low in plant available phosphorus (P). These soils need to be fertilized to increase crop production but due to economic reasons local farmers are unable to afford water-soluble P fertilizers. Instead of expensive superphosphates, the use ofless expensive phosphate rocks such as Togo rock phosphate (TRP), Gafsa rock phosphate (GRP) and 50% partially acidulated rock phosphate (PAPR) are possible alternative P sources for these soils. The rate of dissolution of TRP, GRP, PAPR and TSP in three benchmark soils of Ghana was assessed, and the effectiveness of these P sources determined in a greenhouse using maize (Zea mays var. Toxpino) as a test crop. The dissolution of the P sources in three soils Bekwai, Nzima (Ultisols) and Kokofu (Alfisol) along a toposequence was investigated in an incubationstudy and also in a greenhouse experiment. The rate of dissolution of the P fertilizers was determined in the laboratory by extracting with anion exchange resin membrane (AEM), 0.1M NaOH and 1M HCl at 21 days interval for 105 days. In the greenhouse study, each P source was added at the rate of 60 mg P kg-1 soil, and sown to maize (Zea mays.var.Toxpino) for 28 days. The results of the incubation study showed that the amount of P extracted by the AEM and HCl, following the addition of the P sources, decreased with incubation time in all three soils. However, there was an increase in NaOH-P in all the three soils as incubation progressed. The increase in the NaOH-P suggested that thedissolved P was adsorbed by Fe and Al oxides. The greenhouse results showed that dry matter yield was in the order TSP = PAPR > GRP > TRP. Relative to TRP, the PAPR and GRP were reactive enough to provide plant available P to satisfy the early P requirement for maize growth. Togo PR has little potential for direct application in the three soils

‘Should I Ignore the Promotion System and Stay or I Should Quit’: An Examination of the Experiences of Teachers with the Promotion Process in the Ghana Education Service

Promotion is a key determinant of employee advancement on the organizational ladder. However, in the Ghana Education Service, there are several reports of irregularities in the process which make the promotion less of a merit-based mechanism. The purpose of this study, therefore, was to examine teachers’ perception of fairness in the promotion process and how that affects their willingness to stay in the Service and teach effectively. Using a descriptive survey involving both close-ended and open-ended questions, the opinions and experiences of 342 randomly sampled teachers in the Ejisu-Juaben Municipality were examined using correlations and binary logistic regressions as well as thematic analysis. The results show that fairness in the promotion process was a significant contributor to teacher retention and effective teaching. However, the process is tainted with favoritism and partiality. Governments should, therefore, not be interested in incentivization only as a retention strategy but also come out with strategies aimed at ensuring transparency in the promotion process to make it a performance-based mechanism that sieves and preserves best talents.

Phosphorus sorption capacity in relation to soil properties in profiles of sandy soils of the Keta sandspit in Ghana

The sandy soils of Anloga in the Volta region form part of the Keta basin. The soils are infertile and of low productivity but are intensively cultivated for vegetables such as shallot (Allium cepa).  Farmers have augmented the fertility of the soils by adding cow dung and poultry manure for the past seventy years. To study the P dynamics in the soils, three profiles were dug on cultivated (F) and two on uncultivated (U) fields to study P accumulation and sorption after decades of cultivation. The results showed that total P content was 533 mg P kg-1 at the depth of 50cm and below in the F-profiles compared to 416 mg P kg-1 of similar depthof the uncultivated soils, suggesting some movement of P from the surface soil into the subsoil. The maximum P sorption capacity of the U soils was low (92 6 mg kg-1) but higher than those of the F soils (58.8 mg P kg-1). Multiple regression analyses showed that pH and Ca were the two major determinants of P sorption in the soils. The degree of P saturation (DPS) of the surface soils of the cultivated soils was higher than the average critical value of 25% DPS of an arable land but in the lower depths of the cultivated soils, the DPS decreased tremendously below the critical level of 25% which meant that these depths were not saturated well enough to enhance leaching of P to the underground waters

Desulphurization of drop-in fuel produced through lipid pyrolysis using brown grease and biosolids feedstocks

Biosolids can be incorporated as a water replacement into a two-stage thermal process for biofuel production from brown greases, significantly reducing the overall environmental impact of the process. Unfortunately, the use of biosolids resulted in an appreciable amount of sulphur in the pyrolytic oils produced in the final stage of the process. Here, we first evaluated the relationship between the sulphur content of fatty acids pyrolysis liquid products and pyrolytic conditions. Afterwards, we evaluated the sulphur removal efficiency of several approaches such as distillation, extraction and adsorption. Through a combination of distillation and liquid-liquid extraction, we achieved a desulphurization of up to 95% reaching a final sulphur concentration of 15 ± 4 ppm

Biosolids-based catalyst for oxidative desulphurization of drop-in fuels derived from waste fats

In this work, the catalytic performance of a biosolids-based catalyst was tested in the oxidative desulphurization process of a model fuel solution containing benzothiophene ([S] of 500 ppm), as well as sulphur-rich products from a two-step thermal conversion process of brown grease to renewable hydrocarbons using biosolids as a water replacement during the hydrolysis step. The catalytic results of the biosolids-based material were compared with a classical Fenton-like reagent and a non-catalytic system. Biosolids-based catalyst outperformed the other systems at low temperature with a full desulphurization of benzothiophene solution achieved at 60 °C after 3 h and a good recyclability after four catalytic runs at 80 °C for 3 h. The desulphurization was less effective for hydrolysed fatty acids and crude pyrolysis oil derived from the conversion of brown grease to renewable hydrocarbons, which was due to the composition of the sulphur containing compounds, but still reached 87.7 ± 3.0 % and 74.7 ± 9.5 %, respectively

Implementation of PRSEUS for General Aviation Aircraft

A lighter, more robust airframe is one of the key technological advancements necessary for the successful launch of any large next-generation transport aircraft. Such a premise dictates that considerable improvements beyond current state-of-the-art aluminum structures are needed and improvements will require extensive use of composite materials. Composite materials are light weight and offer the same, if not more, load bearing capabilities when compared to conventional aluminum aircraft structures. NASA and the Boeing Company have been actively working on the development and optimization of a new composite structural concept that presents substantial advantages over traditional aircraft structures. The new concept, named Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), offers damage arresting capabilities and weight reductions for transport category aircraft by eliminating the use of fasteners by employing stitched unitized co-cured panels. . With majority of the aircraft operating under general aviation category, applications of such new structural concepts can be valuable. In addition, when dealing with safety in aviation, airworthiness and crashworthiness are important to consider when creating an aircraft structure. Moreover, general aviation has a higher likeliness to be involved in a crash when compared to transport aircraft with high mortality rates. The PRSEUS structural concept promises improved crashworthiness of general aviation aircraft due to the characteristics of the composite structure having a higher energy absorption compared to conventional aircraft aluminum structures. By implementing the PRSEUS concept structure on a general aviation aircraft such as the Cessna 172 Skyhawk, the nature of carbon fiber composites will offer better crash worthiness and the damage arresting capabilities due to the stitching will allow for higher loading to be applied. In addition, if PRSEUS can successfully perform under primary loads, it could mean weight savings for the aircraft