Effect of chemical agents on morphology, tensile properties and water diffusion behaviour of hibiscus sabdariffa fibers

Effective utilization of Hibiscus sabdariffa fibers in composites applications as a reinforcing fibers in polymer matrix have been a major concern due to its poor mechanical and hydrophilic properties. It will be of benefits to environmental and technological advancement, if its properties are properly handled. In this study, the morphological, tensile and water absorption characteristics of H. sabdariffa fibers was aimed to be investigated. H. sabdariffa fibers was modified using sodium hydroxides, sodium lauryl sulphate and ethylene diamine tetraacetic acid. The morphology using scanning electron microscopy, tensile properties (strength, modulus, elongation and energy at break), water absorption and water diffusion behaviours were studied. Chemical modifications improved fiber surface and roughness, tensile strength and modulus, elongation and energy at break with reduced water absorption of H. sabdariffa fibers. The water diffusion behaviour is less - Fickian controlled by water penetration rate. Hence improved the hydrophobic nature of H. sabdariffa fibers. Keywords: Hibiscus sabdariffa fibers, tensile properties, morphology, water diffusion behaviou

Effect of Chemically Modified Cissus Populnea Fibers on Mechanical, Microstructural and Physical Properties of Cissus populnea/High Density Polyethylene Composites

The effect of chemically modified Cissus populnea (C. populnea) fiber using sodium hydroxide (NaOH) and sodium lauryl sulphate (SLS) on mechanical, morphological and physical (density and water absorption behaviour) properties of C. populnea fiber/recycled HDPE composites was aimed to be investigated. The composites of unmodified and modified C. populnea fiber/HDPE were prepared using injection molding machine. The mechanical properties (tensile strength and modulus, flexural strength and modulus, hardness and impact strength), interfacial shear stress, density, water absorption behaviour, scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscope were studied. The results shows that C. populnea fiber improved the mechanical properties of HDPE matrix with reduced impact strength of the composites. The NaOH and SLS treatments, respectively, improved the mechanical properties of C. populnea fiber/HDPE composites, although NaOH treated C. populnea fiber reduced the tensile modulus. The change in morphology and functional group, respectively, due to the modification was observed in SEM and FTIR. The density and water absorption of the composites, respectively, reduced when SLS modified C. populnea fiber was used compared to untreated C. populnea fiber/HDPE composites. The SLS treated C. populnea fiber prove to be superior for reinforcement, stiffness and light weight material.The effect of chemically modified Cissus populnea (C. populnea) fiber using sodium hydroxide (NaOH) and sodium lauryl sulphate (SLS) on mechanical, morphological and physical (density and water absorption behaviour) properties of C. populnea fiber/recycled HDPE composites was aimed to be investigated. The composites of unmodified and modified C. populnea fiber/HDPE were prepared using injection molding machine. The mechanical properties (tensile strength and modulus, flexural strength and modulus, hardness and impact strength), interfacial shear stress, density, water absorption behaviour, scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscope were studied. The results shows that C. populnea fiber improved the mechanical properties of HDPE matrix with reduced impact strength of the composites. The NaOH and SLS treatments, respectively, improved the mechanical properties of C. populnea fiber/HDPE composites, although NaOH treated C. populnea fiber reduced the tensile modulus. The change in morphology and functional group, respectively, due to the modification was observed in SEM and FTIR. The density and water absorption of the composites, respectively, reduced when SLS modified C. populnea fiber was used compared to untreated C. populnea fiber/HDPE composites. The SLS treated C. populnea fiber prove to be superior for reinforcement, stiffness and light weight material

Optimum prediction for inhibition efficiency of Sapium ellipticum leaf extract as corrosion inhibitor of aluminum alloy (AA3003) in hydrochloric acid solution using electrochemical impedance spectroscopy and response surface methodology

Statistical optimization was used to optimize corrosion inhibition efficiency of Sapium ellipticum leaf extract as corrosion inhibitor of aluminum in acid medium. Response surface methodology was applied, and the effects of four independent variables; acid concentration, inhibitor concentration, temperature, time, and their expected responses were determined. Central composite design a statistical tool was used to generate a total of 16 individual experimental runs, which was previously design to study the effects of these variables during corrosion process. The uniqueness of the model was scrutinized with various criteria including coefficient of determination (R2 = 0.987), p value (< 0.0001), adequate precision (30.22) and coefficient of variation (5.30). The RSM is well fitted in the model which adequately predicted the optimum inhibition efficiency of 96.73% at optimum inhibitor concentration of 1.5g/L-1, acid concentration 1 M, temperature of 303 K and time of 6 hours. Also the electrochemical concept signifies that Sapium ellipticum acts as a mixed-kind inhibitor. The experimental data obtained is in conformity with other research works.   Bull. Chem. Soc. Ethiop. 2020, 34(1), 175-191. DOI: https://dx.doi.org/10.4314/bcse.v34i1.1

Evaluation of Bitter Kola Leaf Extract as an Anticorrosion Additive for Mild Steel in 1.2 M H2SO4 Electrolyte

Plant-based material, namely bitter kola leaf, as an additive for surface modification of mild steel in H2SO4 solution was thoroughly scrutinized using  electrochemical, theoretical and optimization techniques. The functional groups, of the biomolecules of the bitter kola leaf extract, were examined using  Fourier transform infrared spectrometry (FTIR) and gas chromatography-mass spectrophotometry (GC-MS). For clarification purpose, scanning electron  microscopy (SEM) was used to inspect the texture of the degraded and inhibited steel after 21 h of immersion. For the response surface methodology  (RSM), central composite design of Design-Expert Software was used to optimize the inhibition efficiency as a function of acid concentration, inhibitor  concentration, temperature and time. The optimum inhibition efficiency of 93 % was obtained at 0.9 g L–1 bitter kola leaf. The mutual correlation between  the considered variables and expected response was adequately interpreted by a quadratic model. The fitness of the model was justified by the  following standards which include P-value (<0.0001), adjusted R2 (0.9843), R2 (0.991), adequate precision (43.14) and coefficient of variation (2.59). Bitter  kola leaf extract behaved as a mixed-type inhibitor and adequately satisfied Langmuir adsorption isotherm. Furthermore, the theoretical modelling  revealed the most active molecule of bitter kola leaf responsible for the overall inhibition. The experimental and theoretical results are in agreement that   bitter kola leaf extract is a viable corrosion inhibitor of mild steel in H2SO4 solution

Adsorptive treatment of brewery effluent using activated Chrysophyllum albidium seed shell carbon

Chrysophyllum albidium seed shell, an abundant, biodegradable and inexpensive natural resource was used as a precursor to bioadsorbent production for the removal of suspended and dissolved particles (SDP) from initially coagulated Brewery Effluent (BRE). Influence of key parameters such as contact time, bioadsorbent dose, pH and temperature were investigated using batch mode. The thermal behavior studies were evaluated using Thermogravimetric and Differential scanning calorimetric analyses. The morphological observations and functional groups of the bioadsorbents were determined using scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. The adsorption equilibrium, thermodynamics and kinetic of SDP adsorption on H3PO4- treated shell and NH4Cl-treated shell were examined at specified temperatures. Equilibrium data sufficiently fitted the Langmuir isotherm model (R2 > 0.99; SSE < 0.09). The pseudo-second order kinetic model provided the best correlation (R2 > 0.99; SSE < 0.14) with the experimental data. The values of ΔG° and ΔH° indicated the spontaneous and endothermic nature of the process. This study demonstrated that C. albidium seed shell could be utilized as low cost, renewable, ecofriendly bioadsorbent for the uptake of SDP from BRE.http://www.springerplus.com

Synthesis and Physico-chemical Studies of Base Catalyzed Methanolysis of Some Virgin Tropical Seed Oils

The physico-chemical characterization of Prunus amygdalus, Dacryodes edulis and Chrysophillum albidium seed oils were investigated, together with their methyl esters. The vegetable oils were extracted by applying the solvent extraction method, using n-hexane. Prunus amygdalus had the highest oil yield (60.1%), followed by Dyacrodes edulis (55.76 %) and least from Chrysophillum albidium (13.67%). The oils and their biodiesel were then analyzed for acid value, free fatty acid, specific gravity, ash content, iodine value, peroxide value, saponification value, kinematic viscosity, flash point, smoke point, titre value, cloud point, moisture content and refractive index. Accordingly, Dyacrodes edulis seed oil had the highest acid value of 6.57 and required two-step transesterifictaion. The produced biodiesels were discussed in the light of ASTM D 9751, ASTMD 6751 and DIN 14214. These showed yields of 94.36%, 93.03% and 86.49%, cetane numbers of 70.40, 55.20 and 64.57 and calorific values of 31,178.39 KJ/kg, 34,421.50 KJ/kg and 32,838.38 KJ/kg for Prunus amygdalus, Dacryodes edulis and Chrysophyllum albidium, respectively. Other fuel-related properties showed highly improved qualities upon transesterification and compared well with ASTM and EU standards. The overall results showed that the seed oils are viable for biodiesel production

Cissus Populnea Fiber - Unsaturated Polyester Composites: Mechanical Properties and Interfacial Adhesion

Mechanical (flexural, hardness, and impact) properties and interfacial adhesion of acetic anhydride (AC) and ethylene diamine tetraacetic acid (EDTA) treated Cissus populnea fiber-unsaturated polyester (UPR) composites was investigated because of poor durability of the natural fiber-UPR composite applications. UPR composites were prepared with untreated and optimally treated fiber using hand-lay-up technique. Optimization of mechanical properties and interfacial adhesion between the fiber and UPR were determined using response surface methodology and fiber pull-out method, respectively. AC and EDTA treated fibers improved the flexural and hardness properties and interfacial adhesion at reduced impact strength. This is corroborated with morphology of the composites

Novel imidazole based ionic liquid as anti-corrosion additive for aluminum alloy: Combined experimental, DFT/MD simulation and soft computing approach

The anti-corrosion effectiveness of novel 1‑butyl‑3-methylimidazolium tetrachloroindate ionic liquid ([C4MIM][InCl4] (IL)) for aluminum-silicon-titanium (Al-Si-Ti) based aluminum alloy in 1mole (M) potassium hydroxide (KOH) electrolyte at 303–343 K was explored in the current study. To realize this, standard methods such as weight loss, electrochemical investigation, density functional theory (DFT)/molecular dynamics simulation (MD-simulation), scanning electron microscope (SEM), and scanning force microscopy (SFM), were employed to scrutinize the anti-corrosion successfulness of [C4MIM][InCl4] for aluminum alloy in KOH solution. From our findings, the ionic liquid mitigated the corrosion of Al-Si-Ti aluminum alloy, and the inhibition efficiency (IE%) is enhanced with improved ionic liquid concentration. The inhibition efficiencies obtained at 0.8 g/L [C4MIM][InCl4] concentration were 88.46%, 82%, and 82.35%, for gravimetric, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) procedures, respectively. PDP result disclosed [C4MIM][InCl4] performed like a mixed-type inhibitor of a cathodic predominance. The SEM/SFM examination proved that the ionic liquid developed a shield coat on the metal alloy surface. The thermodynamic probe disclosed [C4MIM][InCl4] molecules fastened onto Al-Si-Ti aluminum alloy surface by physisorption mechanism and best fitted the Frumkin adsorption isotherm model. The DFT/MD-simulation procedure confirmed the adsorption configuration and orientation of [C4MIM][InCl4] molecules in gas and aqueous phase which is in harmony with the experimental discovering. Simulated neural network (SNN), and the adaptive neuro-fuzzy inference system (ANFIS) were deployed for a robust training, forecast and modeling of the interactive effects of the input parameters and the expected feedback, Herein, training via the ANN and ANFIS designs without (GA), as well as computing the statistical indices such as the mean squared error (MSE), hybrid fractional error function (HYBRID%), absolute average relative error (AARE), Marquardt's percentage standard deviation (MPSED%) and r-squared (R2) were employed to appraise the models capability. The optimal IE% forecasted was 88.4842% and 89.0643%, for the ANN and ANFIS, respectively. Based on the numerical values of the ANN and ANFIS parameters calculated much acceptance was accorded to the ANFIS model over the ANN due its high degree of precision and robustness. The aftermath of this study furnishes additional information on systematic plan of corrosion mitigation, and proffer useful instructions for the logical use of [C4MIM][InCl4] as anti-corrosion additive for Al-Si-Ti aluminum alloy threatened by alkaline solution