Physico-Chemical Characterization of Wood Ash for Agronomic Purposes

The oil refinery of the food products company SOPAL, located in the port area of TOGO, produces an average of 200 kg of eucalyptus wood ash per day. This ash is stored in large quantities within the premises of the refinery, without any disposal solution. The aim of this study is to identify the physico-chemical properties of SOPAL’s wood ash for agronomic valorization. Physico-chemical analyses reveal the presence of major and secondary elements such as potassium (15.71 g/kg DM), phosphorus (27.90 g/kg DM), calcium (9.76 g/kg DM), magnesium (0.03 g/kg DM), sodium (1.24 g/kg DM), iron (1.49 g/kg DM) and manganese (7.82 g/kg DM). The pH is alkaline (12.97) with fairly high conductivity (24.10 mS/Cm). Heavy metals identified are cobalt (0.19 mg/kg DM), cadmium (0.10 mg/kg DM), lead (1.14 mg/kg DM), copper (19.77 mg/kg DM) and nickel (12.82 mg/kg DM). The results show that the ash contains considerable amount of major and secondary elements for agronomic uses.

Experimental and mathematical modeling of Cr(Ⅵ) removal using nano-magnetic Fe3O4-coated perlite from the liquid phase

Modification of perlite using nano-magnetic iron oxide was implemented to produce nano-magneticFe3O4-coated perlite composite(Fe3O4/Perlite).The prepared composite was characterized using Scanning Electron Microscopy,Fourier-Transform Infrared spectroscopy and Powder X-ray Fluorescence.The potentiality of both perlite and Fe3O4/Perlite composite to eliminate Cr(VI)from the environmentally relevant water was investigated.The influence of main factors which could affect the adsorption was studied including;pH of medium,shaking time and Cr(VI)ions concentration.The experimental outcome demonstrated that the modification of perlite by nano-magnetic Fe3O4 showed a significantly enhanced Cr(VI)removal efficiency relative to that of unmodified perlite.From the kinetic studies,the experimental data fitted well with the pseudo-second-order model.Moreover,it proposes that Langmuir isotherm is more adequate than the Freundlich isotherm for both perlite and modified perlite.The results recommended that Fe3O4/Perlite composite had a great potential as an economic and efficient adsorbent of Cr(VI)from contaminated water,which has huge application potential.

Simple and sensitive method for the determination of trace amounts of thorium using a benzoquinone derivative

A novel simple, sensitive, rapid, direct, and spectrophotometry-based procedure was investigated to determine Th(IV) at trace amounts. The new method is based on Th(IV) chelation with 3,6-dichloro-2,5-dihydroxy-l,4-benzoquinone(DDBQ). The reagent reacts with Th(IV) in 0.1 M HCl to form an orange 1:2 complex. The stability constant value is 6.62×10~4 for the Th(IV)complex. The Th(IV)-DDBQ obtained shows one peak with a maximum at about 346 nm. The chelate forms immediately and the absorbance remains stable for over24 h. Beer's law was obeyed in the concentration range0–10 μg mL^(-1). The molar absorptivity and Sandell's sensitivity were 4.4×10~4 L mol^(-1)cm^(-1) and 0.0053 μg cm^(-2), respectively. Different analytical parameters were tested in detail. Interfering ion(cations and anions) effects were tested. Methods for Th(IV) determination by second and third-derivative spectrophotometry were also introduced at about 344 and 341 nm, respectively. These two derivative orders offer the feature of sensitivity without the necessity for solvent extraction,heating, or pre-concentration steps. Finally, the methods were successfully utilized for Th(IV) determination in monazite, environmental water, and wastewater samples.

Removal of Alcyon II, CGR, MeV ⁶⁰Co Teletherapy Head and Evaluation of Exposure Dose

Teletherapy units containing 60Co source are used in Egypt and worldwide for treatment of cancer diseases. One of the widely used in Egypt is Alcyon CGR MeV. Different radiotherapy facilities need to unload this 60Co unit after being disused. The head containing the source was removed and put into approved package for transportation, after the source kept in safe position. This study describes the planning and removing process of the disused sources and, transports it into its head. The personal doses measured during the process. This work pre-estimates the doses received to workers during the removing process. The workers received doses of approximately 55 μSv during the whole process. This study shows that the original lead head can be used as the source container of this 60Co unit but not as a long term storage option. The 60Co machine was smoothly dismantled and transported by trained workers and driver, using planned and controlled radiation protection, followed by ALARA (as low as reasonably achievable) rule.

Impact of Composts Maturity on Growth and Agronomic Parameters of Maize (<i>Zea mays</i>)

Several methods have been developed in the literature which allow the maturity of composts to be assessed before it is used in agriculture. The objective of this study is to assess the maturity of the composts produced at the platform of the NGO ENPRO in Lomé on the growth and agronomic parameters of maize (Zea mays L., var. IKENE). To do so, three types of compost (gargabe, fruit waste, animal litter) were made for at least 3 months. The chemical analysis, phytotoxicity and agronomic tests carried out made it possible to assess the maturity of these composts. Indeed, the evolution of the C/N ratio, of the electrical conductivity, the phytotoxicity tests and the growth parameters of the composts show that the composts N°1 and N°2 are mature at the end of the 3rd month of composting while the compost N°3 can only be considered mature at the end of the 5th month of composting. But, with a yield of 2.39 ± 0.28 t/ha and a mass of 1000 grains of 346 ± 4 g, the treatment at 5 t/ha of compost N°3, has the best agronomic parameters compared to other types of compost and treatment without organic amendment. These results also show that compost with a high electrical conductivity has an inhibitory effect on the growth of corn plants (Zea mays L., var. IKENE). Basic chemical analysis, phytotoxicity tests and height growth of maize (Zea mays L., var. IKENE) are relatively efficient methods for evaluating the maturity of composts.

Stabilization of Spent Grains by Composting: Case of the BB Brewery in Lomé(Togo)

Brewery grains have a long history in animal feed. This use in animal feed nevertheless poses a problem, that of bad odors due to the sometimes too long shelf life of spent grains. The objective of this work is to recover spent grains from the BB brewery in Lomé by composting in order to stabilize them. A compost based solely on spent grains was produced after 5 months. The physico-chemical and spectroscopic characterizations at the end of the composting process revealed that the compost obtained has interesting properties with a pH = 7.01;a C/N ratio of 13.7 and a low level of heavy metals (Pb = 1.23 mg/kg, Cd = 0.04 mg/kg etc.).

Trace Element Concentrations in Soft Tissue and Shell of the Mangrove Oyster (<i>Crassostrea Gasar</i>Dautzenberg, 1891) from the Lake Zowla-Aného Lagoon Hydro System (Southern Togo)

The Lake Zowla-Aného lagoon hydro system, located on the southeast coast of Togo, is very exposed to metal contamination as it receives a huge amount of untreated domestic and industrial effluents from Aného City and the phosphorite treatment plant at Kpémé. This study aims to assess the concentrations of seven heavy metals and their bioaccumulation status in soft tissues and shells of the mangrove oyster (Crassostrea gasar) collected from this aquatic environment. Samples were collected in January, April and July 2017 at two stations and analyzed using flame atomic absorption spectrophotometry. Results indicate that the waters are contaminated by Cd, Pb and Cr with average concentrations that are significantly above WHO standards. At both locations, the contents of the trace elements (except Cr) in oysters’ soft tissues were significantly higher than those in the shells. In the soft tissues, the concentration of Cr, Cu, Zn, As, Cd, Hg, and Pb ranged (in mg·kg-1) from 4.33 to 23.14, 93.4 to 366.7, 455.68 to 1384.15, 0.11 to 1.34, 16.42 to 62.6, 0.05 to 0.473 and 0.39 to 21.08, respectively. Furthermore, statistical analyses showed marked differences in mean concentrations between sampling time on the one hand, and between sampling locations on the other hand (p < 0.05). The highest metal concentrations were recorded in oysters collected in June at Zalivé whereas the lowest values were recorded in April at Zowla. Based on BCF results in the lagoon system, the oyster C. gasar can be used as a biomonitor of Zn, Cd, Cu and Hg exposure. Finally, the Cd, Pb, As, Zn and Cu concentrations in soft tissues and were found to be significantly higher than the permissible limit for human consumption according to WHO and FAO and thus pose a threat to human health.

Surface charge property governing co-transport of illite colloids and Eu(Ⅲ) in saturated porous media

The transport of colloids and radionuclides is sophisticated because of the variety of charge properties between colloidal particles and host subsurface media, which causes great difficulty in establishing a reliable model of radionuclides migration by taking the colloid phase into consideration. In this work,the co-transport of illite colloids(IC) and Eu(Ⅲ) in the quartz sand and iron-coated sand porous media was investigated by column experiments to address the predominant mechanism of charge properties on co-transport. Results showed that Eu(Ⅲ) transport was driven by the illite colloids and electrostatic interaction was critical in governing the co-transport patterns. The promotion of Eu(Ⅲ) transport by IC was attenuated in the iron-coated sand systems;more IC-Eu(Ⅲ) complexes were retained uniformly in the column. The pore throat shrinkage caused by electrostatic attachment between aggregated IC and iron oxides exacerbated the physical straining and size exclusion effect of IC-Eu(Ⅲ) complexes. An aggravated irreversible retention of IC-Eu(Ⅲ) was detected in iron-coated sand column due to the electrostatic attraction of IC-Eu(Ⅲ) to host media. The findings are essential for improving the understanding on the potential transport, retention and release risk of colloids associated radionuclides, and imply that the positively charged permeable reactive barrier is an effective strategy to reduce the transport risk of colloid associated radionuclides.

Biochar as construction materials for achieving carbon neutrality

Biochar is a waste-derived material that can sequester carbon at a large scale.The development of low-carbon and sustainable biochar-enhanced construction materials has attracted extensive interest.Biochar,having a porous nature and highly functionalised surface,can provide nucleation sites for chemical reactions and exhibit compatibility with cement,asphalt,and polymer materials.This study critically reviewed the state-of-the-art biochar-enhanced construction materials,including biochar-cement composites,biochar-asphalt composites,biochar-plastic composites,etc.The efficacies and mechanisms of biochar as construction materials were articulated to improve their functional properties.This critical review highlighted the roles of biochar in cement hydration,surface functional groups of engineered biochar for promoting chemical reactions,and value-added merits of biochar-enhanced construction materials(such as humidity regulation,thermal insulation,noise reduction,air/water purification,electromagnetic shielding,and self-sensing).The major properties of biochar are correlated to the features and functionalities of biochar-enhanced construction materials.Further advances in our understanding of biochar’s roles in various composites can foster the next-generation design of carbon-neutral construction materials.