Organic acid-catalyzed hydrolysis of Magnesium hydride for generation of hydrogen in a batch system hydrogen reactor
- Authors: Adeniran, Joshua Adeniyi , Akinlabi, Esther Titilayo , Chen, Hong-Sheng , Fono-Tamo, Romeo , Jen, Tien-Chien
- Date: 2017
- Subjects: hydrolysis, hydrogen generation , Hydrolysis , Hydrogen generation , Kinetics
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/241943 , uj:24943 , Citation: Adeniran, J.A. 2017. Organic acid-catalyzed hydrolysis of Magnesium hydride for generation of hydrogen in a batch system hydrogen reactor.
- Description: Abstract: Hydrogen generation from MgH2 is of interest to the research community due to various alluring attributes of MgH2 as a hydrogen generation substrate. In this study MgH2 powder was utilized as a substrate in hydrolysis reaction catalyzed by acetic acid, an environmentally friendly and relatively cheap acid. The reaction was conducted in a hydrogen generation reactor operated in a batch mode. Three sample weights (0.4g, 0.8g and 1.2g) of the substrates were utilized for the experiment at 40, 50, 60 and 70 wt% acetic acid concentration at 50 °C for investigation of the roles of substrate weigh and catalyst concentration on hydrogen yield. The results indicated that MgH2 powder weight influenced hydrogen generation more compared to the catalyst concentration. The highest hydrogen yield in the study was 0.048 L hydrogen gas from 0.4g MgH2 powder (70 wt% acetic acid) while the highest hydrogen generation was reported when 1.2g substrate hydrolyzed in 50 wt% acetic acid.
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Kinetic studies of nickel dissolution from ammonium jarosite precipitate in an alkaline medium
- Authors: Malenga, Edward Ntumba , Nheta, W. , Mulaba-Bafubiandia, A.F.
- Date: 2014
- Subjects: Kinetics , Dissolution , Ammonium jarosite precipitate
- Type: Article
- Identifier: uj:4801 , http://hdl.handle.net/10210/12055
- Description: The dissolution kinetics of nickel from ammonium jarosite precipitate in an alkaline medium was investigated. The effects of various parameters were studied to optimize the dissolution conditions and to determine the kinetics on the leaching process based on the shrinking core model...
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Leaching kinetics on the removal of phosphorus from waste phosphogypsum by application of shrinking core model
- Authors: Mashifana, Tebogo , Ntuli, Freeman , Okonta, Felix
- Date: 2018
- Subjects: Phosphogypsum , Leaching , Kinetics
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/286415 , uj:30991 , Citation: Mashifana, T., Ntuli, F. & Okonta, F. 2018. Leaching kinetics on the removal of phosphorus from waste phosphogypsum by application of shrinking core model. South African Journal of Chemical Engineering, 27:1-6. https://doi.org/10.1016/j.sajce.2018.11.001
- Description: Abstract: This study investigated the removal of phosphorus from waste phosphogypsum by using citric acid as a leaching reagent, evaluated the potential environmental effect of the final product produced and provide recommenda- tions for the application of developed products. A dissolution process was applied and three variables were studies namely, concentration, stirring speed and temperature. The results showed that Phosphorus can suc- cessfully be removed from waste phosphogypsum and the optimum leaching conditions were at the con- centration of 0.5 M and temperature of 40 °C, with no effect observed on varying the stirring speed. Shrinking core model (SCM) was used to determine the best fit for the experimental data. For the pore diffusion model (KD), all correlation coefficients yielded were above 0.9, illustrating a positively linear correlation of KD and leaching behavior for phosphorus. Pore diffusion proved to be the effective rate controlling mechanism for the removal of phosphorus from phosphogypsum. The analysis of moments of particle size distribution (PSD) also showed a reduction in particle size, indicating the dissolution of the solid particles. The application of Toxic Leaching Characteristic Procedure (TLCP) showed low concentrations on the effluent, indicating that the de- veloped product will not contaminate the environment through leaching. The obtained leachate concentrations were within the South African effluent discharge standards. The results also showed that dissolution had a significant contribution on the moments of particle size distribution, in terms of the volume, surface area and particles number. In respect to unconfined compressive strength the products developed can be used for load bearing and as backfill material.
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Modelling the kinetic of biogas production from co-digestion of pig waste and grass clippings
- Authors: Matheri, Anthony Njuguna , Belaid, Mohamed , Seodigeng, Tumisang , Ngila, Catherine Jane
- Date: 2016
- Subjects: Anaerobic , Co-digestion , Kinetics , Mesophilic temperature , Modified gompertz
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93635 , uj:20372 , Citation: Matheri, A.N. et al. 2016. Modelling the kinetic of biogas production from co-digestion of pig waste and grass clippings.
- Description: Abstract: This work investigated the use of laboratory batch anaerobic digester to derive kinetics parameters for anaerobic co-digestion of pig waste and grass clippings. Laboratory experiment data from 10 litres batch anaerobic digester operating at ambient mesophilic temperature of 37 0C and pH of 6.9 was used to derive parameters for modified Gompertz model. The carbon/nitrogen (C/N) ratio of Pig waste was found to be 16.16 and grass clippings to be 20.54. Through co-digestion in ratio of 1:1, the C/N ratio settled at 17.28. The actual biogas yield was found to be 7725 ml/g COD. In the model of biogas production prediction, the kinetics constants of A (ml/g COD), μ (ml/g COD. day), λ (day) was 7920.70, 701.35, 1.61 respectively with coefficient of determination (R2) of 0.9994. Modified Gompertz plot showed better correlation of cumulative biogas production and these results show biogas production can be enhanced from co-digestion of substrates.
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