The dissolution study of a South African magnesium-based material from different sources using a pH-stat

One of the main steps in the wet flue gas desulphurization (WFGD) process is the dissolution of either magnesite or limestone. Evaluating the magnesite dissolution rate is vital for the design and efficient operation of wet FGD plants. A study on the dissolution of magnesite from different sources in South Africa is presented in this work. The effect of reaction temperature (303.15-343.15K), solid-to-liquid ratio (0.5-2.5g/200 ml), particle size (25-125μm), pH (4-6) and HCl concentration (0.5-2.5 mol/l) on the dissolution rate was studied. It was found out that the dissolution reaction follows a shrinking-core model with the chemical reaction control as the rate-controlling step. The dissolution rate increased with an increase in concentration and reaction temperature and with a decrease in particle size and solid-to-liquid ratio. The activation energy of this dissolution process was found to be 45.685 kJ/mol

Production of Biodiesel from Waste Vegetable Oil (WVO) using Nano CaO-NCC catalyst: Modelling and Optimization using Central Composite Design (CCD) in Response Surface Methodology (RSM)

Biodiesel production as a fuel in diesel engines has expanded dramatically in recent years and is likely to increase more in the near future. Increasing biodiesel consumption requires optimized production techniques that allow for significant production capacities, simplified operations, high yields, and the usage of more cost-effective feedstocks such as waste oils and fats. In this study, biodiesel was produced from waste vegetable oil (WVO) and Methanol (CH3OH) in the presence of a nanoCaONCC catalyst that was derived from industrial waste that mainly consists of Calcium Carbonate (CaCO3). The produced nanoparticle catalyst was characterized by using FTIR, SEM, and XRD. Response surface methodology (RSM) was used to determine the optimum operating conditions for the highest biodiesel yield. After applying the RSM methods using the CCD experimental design, the optimum biodiesel production was found to be at a temperature of 55 °C, catalyst loading of 1.25 % w/v, Methanol to oil ratio of 1:5 w/w, and reaction time of 75 min with an average yield of 94.01 %. The FTIR showed the presence of the CaO and NCC functional groups. SEM image revealed that the produced catalyst is more porous, with a small particle size. The XRD pattern presented the presence of cellulose (NCC) and Calcium Oxide (CaO) nanoparticles in the synthesized catalyst. The R2 of 0.963 was found to be for the mathematical models to predict biodiesel production

Thermal and mechanical properties of investment casting pattern material based on paraffin wax fortified with LLDPE and filled with PMMA

The thermal and mechanical properties of paraffin wax, linear low-density polyethylene (LLDPE) and poly (methyl methacrylate) (PMMA) microbeads formulations were prepared via extrusion process. The blends were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and its tensile properties (stress at break, strain at break and modulus of elasticity and). The results indicated that both LLDPE and PMMA had an influence on the thermal properties and the tensile properties of the blends. The TGA analysis showed that the thermal stabilities of the developed polymer increased and also at temperatures above 600 °C, there was no residue. DSC curves of the blends indicated two main exothermic peaks at 60 °C and 120 °C. This could be probably due to the wax structure and the LLDPE peak structure. DSC curves further suggested that the compatibility of the paraffin wax/LLDPE two phases increased with an increase in the filler content. The bending stress at break and the Young’s modulus increased with increasing LLDPE content whereas the PMMA beads increased modulus there was no gradual strain increment.https://aip.scitation.org/journal/apcpm2021Chemical Engineerin

Structural Features of Cellulose and Cellulose Nanocrystals via In Situ Incorporation of Magnetic Iron Oxide Nanoparticles: Modification and Characterization

This work reports on the structural modification of cellulosic materials with magnetic iron oxide nanoparticles through the co-precipitation method. Cellulose is one of the most abundant natural polymers with chemical variability brought about by the presence of several hydroxyl groups, allowing its surface modifications through the insertion of several chemical groups to impact its cellulosic characteristics. Thus, the objective of this study was to synthesize magnetic iron oxide nanoparticles (MNPs) through co-precipitation, followed by in situ incorporation of MNPs onto chemically purified cellulose (CPC) and cellulose nanocrystals (CNC). The composites were characterized for thermal properties using TGA, molecular structure using FTIR, surface morphology using SEM, elemental composition using electron dispersion spectroscopy (EDS), and crystallinity using XRD. The prepared composites presented improved crystal, thermal, and surface properties. CNC-MNPs and CPC-MNPs bore particle sizes of 26.94 and 37.72 nm, respectively, whereas MNPs’ particle size was 10.3 nm. EDS analysis indicated that Fe, C, and Cl were the main elements present in the composites. Surface modification of the cellulosic materials presented excellent sorption surface properties and can be used in several industrial processes, such as wastewater purification, air filtration, and various environmental remediation processes

An epidemiological analysis of Acute Flaccid Paralysis (AFP) surveillance in Kenya, 2016 to 2018

Background: The poliovirus has been targeted for eradication since 1988. Kenya reported its last case of indigenous Wild Poliovirus (WPV) in 1984 but suffered from an outbreak of circulating Vaccine-derived Poliovirus type 2 (cVDPV2) in 2018. We aimed to describe Kenya's polio surveillance performance 2016-2018 using WHO recommended polio surveillance standards. Methods: Retrospective secondary data analysis was conducted using Kenyan AFP surveillance case-based database from 2016 to 2018. Analyses were carried out using Epi-Info statistical software (version 7) and mapping was done using Quantum Geographic Information System (GIS) (version 3.4.1). Results: Kenya reported 1706 cases of AFP from 2016 to 2018. None of the cases were confirmed as poliomyelitis. However, 23 (1.35%) were classified as polio compatible. Children under 5 years accounted for 1085 (63.6%) cases, 937 (55.0%) cases were boys, and 1503 (88.1%) cases had received three or more doses of Oral Polio Vaccine (OPV). AFP detection rate substantially increased over the years; however, the prolonged health workers strike in 2017 negatively affected key surveillance activities. The mean Non-Polio (NP-AFP) rate during the study period was 2.87/ 100,000 children under 15 years, and two adequate specimens were collected for 1512 (88.6%) AFP cases. Cumulatively, 31 (66.0%) counties surpassed target for both WHO recommended AFP quality indicators. Conclusions: The performance of Kenya's AFP surveillance system surpassed the minimum WHO recommended targets for both non-polio AFP rate and stool adequacy during the period studied. In order to strengthen the country's polio free status, health worker's awareness on AFP surveillance and active case search should be strengthened in least performing counties to improve case detection. Similar analyses should be done at the sub-county level to uncover underperformance that might have been hidden by county level analysis