Influence of Urena lobata Fibre Treatment on Mechanical Performance Development in Hybrid Urena lobata: Fibre/Gypsum Plaster Composites

Autogenous shrinkage is related to the chemistry and changes in the internal structure of the cement concrete paste on drying. This problem of drying shrinkage in early stages that occur without any moisture transfer to the surrounding environment has triggered the incorporation of fibres in the cement concrete matrix to fill the micropores and control cracking (autogenous shrinkage). This study aimed at investigating the potential use of Urena lobata (UL) fibre as microreinforcement in enhancing mechanical properties of hybrid UL-fibre/gypsum cement composites used for plasters. The fibre was harvested from the coastal region of Cameroon and treated with 0.06 M NaOH over different periods. Dispersion of treated fibre bundles in the composite (at Wt. % UL-fibre dosages of 0, 1.5, 2.5, and 3.5) was facilitated by blending with the cement paste which also helped to improve interfacial bonding between the fibre and the cement matrix. The moisture/water absorption and flexural properties within the hardened cement matrix were quantitatively assessed, and it was observed that the incorporation of treated fibre accelerated the hydration process. The test results showed an increment in compressive strength and reduction in autogenous shrinkage for the hybrid UL fibre/gypsum cement composites, while lower percentage additions (less than 2.5%) of untreated fibre appeared to have adverse effects on specimens. It was observed that properly dispersed (blended) treated UL fibres filled the fine pores in the cement matrix by providing an additional nucleation site that resulted in a denser microstructure, which in turn enhanced the strengths and limited the autogenous shrinkage

Structural Characterization and Magnetic Properties of Undoped and Ti-Doped ZnO Nanoparticles Prepared by Modified Oxalate Route

Ti-doped zinc oxide and pure zinc oxide nanoparticles were synthesized by a modified oxalate route using Averrhoa carambola fruit juice as a natural source of oxalate. The characteristics of the precursors have been investigated by FTIR, TGA, and XRD. The results from the investigation revealed that the precursors are zinc oxalate and Ti-doped zinc oxalate which readily decompose at 450°C. The as-prepared precursors were calcined at 450°C for 4 hours, and the decomposition products have been characterized by XRD, SEM, EDX, and VSM. XRD results revealed crystallinity with hexagonal wurtzite structure, while the average grain size was found to be 26 nm for Ti-doped ZnO and 29 nm for ZnO, using calculations based on Debye-Scherrer equation. Furthermore, the morphological studies by SEM showed particle agglomeration, while the presence of Ti3+ in the zinc oxide lattice is indicated by EDS analysis. Finally the hysteresis loop from VSM results shows that Ti-doped ZnO exhibits ferromagnetism

Structural characterization and magnetic properties of undoped and copper-doped cobalt ferrite nanoparticles prepared by the octanoate coprecipitation route at very low dopant concentrations

Nanoparticles of undoped and copper-doped cobalt ferrite Co1−xCuxFe2O4 at very low dopant concentrations (x = 0; 0.02; 0.04; 0.06; 0.08) were successfully synthesized by pyrolysis of the corresponding hetero metal octanoate precursors obtained via coprecipitation using the octanoate ligand as precipitating agent. The precursors were then characterized by FTIR, ICP-AES and TG-DTA analyses and the results reveal the formation of a copper-cobalt-iron hydroxooctanoate represented by the formula [Co1−xCuxFe2(C8H15O2)6(OH)2·2H2O]. The decomposition products obtained upon pyrolysis in air at 400 °C for 3 h were characterized by FTIR, XRD, SEM, TEM, XPS and VSM analyses. FTIR and XRD analyses showed the formation of a single phase mixed spinel ferrite while TEM analysis showed that the particles have a spherical shape with a mean size of 20 nm and form spherical agglomerates with sizes reaching 500 nm in some cases as the SEM images show. The chemical states of the metallic species in the samples were revealed by XPS to be Cu2+, Co2+ and Fe3+. These results combined with XRD confirmed the mixed spinel structure, Co1−xCuxFe2O4 in which Cu2+ ions substitute Co2+ ions in tetrahedral sites for x lower than 0.06 and in octahedral sites for x between 0.06 and 0.08. Magnetic parameters such as saturation magnetization (Ms), coercivity (Hc), remanent magnetization (Mr), magnetocrystalline anisotropy constant (K) and reduced magnetization (Mr/Ms), obtained from magnetic hysteresis loops measured at room temperature, are in agreement with this mixed spinel structure and also indicate that these materials are ferromagnetic and could be good candidates for applications in biomedicine and in microwave devices

Nanosize CaCu3Ti4O12 Green Synthesis and Characterization of a Precursor Oxalate Obtained from Averrhoa carambola Fruit Juice and Its Thermal Decomposition to the Perovskite

Improving on the very high temperatures used in solid-state synthesis routes to prepare CCTO ignited the idea of using oxalate routes which make use of organic solvents in the synthesis of CCTOX as oxalate intermediates to the decomposition product, CCTO. The use of commercial oxalic acids and oxalate has not only recorded a solubility problem which reflects on the size, shape, homogeneity, and morphology of the final product but also has an environmental impact originating from the solvents used. Both the composition and morphology of these inhomogeneities play a role in the behaviour of the final product, pointing out the need to assess the dependence of size, shape, homogeneity, and morphology and the material performance on the sample synthesis history. In this study, nanosized particles of calcium copper titanium oxide, CaCu3Ti4O12 (CCTO), were successfully synthesized by pyrolysis of the corresponding heterometal oxalate precursors obtained via coprecipitation using the edible carambola fruit juice as a precipitating agent and investigated in detail. The precursors were characterized, and the results revealed the formation of a single molecular precursor represented by the formula CaCu3(TiO)4(C2O4)8·9H2O (CCTOX). The decomposition products, obtained via calcination in air, were subsequently subjected to thermal treatments at different temperatures for 4 hours. The morphology and microstructure were characterized, and analysis showed the formation of a single phase, CaCu3Ti4O12 (CCTO) with CuO and CaTiO3 as impurity. It was observed from microscopy that the samples obtained from sintering at 600°C for four hours had discrete particles with regular morphology, limited size distribution, high degree of homogeneity, and multiple dimensions ranging between 10 and 35 nm and showed some degree of ellipticity in shape. Increasing the sintering temperature from 600°C to 700°C and 800°C increased the grain growth in the ceramic as well as the densification. The method makes advantage of the fact that oxalate precursors decomposed at relatively lower temperatures and the fact that the oxalate in the juice is in the solution which downplays both the solubility and environmental pollution problems since no additional solvents are used

Oxalate Free Averrhoa Carambola Fruit Juice and Wine Produced by a Modified Oxalate Route (Synthesis of Zinc Oxalate)

Carambola is highly valued for its fruits, especially the pulp which is used for a wide variety of domestic and industrial purposes. The Carambola fruit is a nutritious food containing acids, vitamins, phytosterols and other phytochemicals. The drinks (Fruit juice and fruit wine) from Averrhoa Carambola L. are specific due to their taste and flavor. However, they contain oxalate at concentrations which are not health promoting when consumed. We are taking this advantage to explore wine fermentation from Carambola fruit pulp by focusing on the effect of different parameters such as time of treatment for juice extraction, yeast inoculate for wine fermentation and secondary fermentation to wine quality, and to  precipitated the oxalate ions from the juice and wine using metal zinc ions as a fruit metal.  The main fermentation was done at 25o C in 13 days, and 1 week of secondary fermentation in dark bottle at 25o C. The wine produced was characterized for alcoholic content, pH, titratable acidity, Brix, and consumer acceptability while the precipitate (Zinc Oxalate) was characterized by FTIR and PXRD. The carambola fruit pulp juice and wine produced were of acceptable quality (clear, sweet, sparkling, smooth and flavoured) following the olfactory test. The drink had a pH of 4.02 and 11.2 %, alcohol content while the FTIR and PXRD results revealed that oxalate ions were precipitated from the juice and wine by zinc ions, and   after precipitation of the juice and wine, the oxalate concentration in the drinks were reduced to health promoting levels. Furthermore, the precipitation process did not affect the acceptability of the wine as the olfactory parameter were not actually affected