D. Konadu - Academia.edu (original) (raw)

Papers by D. Konadu

Research paper thumbnail of Concrete Rebar Corrosion Inhibitors - A Review of Sustainable Natural Inhibitors

Sustainable Education and Development – Making Cities and Human Settlements Inclusive, Safe, Resilient, and Sustainable, 2022

Research paper thumbnail of Investigation of formation of precipitates and solidification temperatures of ferritic stainless steels using differential scanning calorimetry and Thermo-Calc simulation

The phase transformations in unstabilized and stabilized ferritic stainless steels during solidif... more The phase transformations in unstabilized and stabilized ferritic stainless steels during solidification were studied using Thermo-Calc and differential scanning calorimetry (DSC). The solidus and liquidus temperatures of the Thermo-Calc simulations were compared to the liquidus and solidus temperatures measured with DSC. Thermo-Calc software revealed the precipitates of the ferritic stainless steels to be MnS, TiN, Ti4C2S2, NbC, and Ti(C,N). Given the low volume fraction of precipitates, DSC could not be used to reveal the onset of precipitation. There was reasonable correlation between the liquidus and the solidus temperature, as calculated using Thermo-Calc and as measured using DSC. Generally, a higher niobium content resulted in a higher solidification temperature range.

Research paper thumbnail of Potential Application of Dioctyl Sodium Sulfosuccinate Salt (DOSS)–Saponin Binary Dispersant in Oil Spill Remediation: Synergistic Interaction Between DOSS and Saponin

Water, Air, & Soil Pollution, 2020

The interfacial activity of dispersants can be enhanced by combining two or more surfactants to f... more The interfacial activity of dispersants can be enhanced by combining two or more surfactants to formulate the dispersant. This paper examines the effects of Bio-Saponin (BS), a phytogenic surfactant on the interfacial activity of synthetic dioctyl sulfosuccinate sodium salt (DOSS) usually adopted as a suitable surface-active agent in dispersants used in dealing with large-scale oil spills. The o/w emulsion created with the binary DOSS-BS was very stable and recorded the least average droplet size compared with that of DOSS only and BS only. Lower surface and interfacial tension values were also obtained from the DOSS-BS binary formulation. The dispersion effectiveness was also higher compared with that of DOSS and BS. However, they were dependent on the salinity and type of crude oil. These observations were attributed to the moderation of the interaction between the anionic head group of DOSS by the polysaccharide hydrophilic group of BS. The results revealed the potential application of DOSS-BS binary dispersant in oil spill remediation and in other processes that would require an effective emulsifier.

Research paper thumbnail of The influence of Ti and Nb on solidification cracking of ferritic stainless steels, as determined using self-restrained samples

Welding in the World, 2019

We investigate precursors of an excited state quantum phase transition in the quasienergy spectru... more We investigate precursors of an excited state quantum phase transition in the quasienergy spectrum of the kicked top. Using a semiclassical approach, we analytically obtain a logarithmic divergence in the density of states, which is a hallmark of a continuous excited state quantum phase transition. We propose a protocol to observe the cusp behavior of the magnetization close to the critical quasienergy.

Research paper thumbnail of Physico-mechanical properties of bauxite Residue-clay bricks

Research paper thumbnail of NANOSTRUCTURED TiO2 AND THEIR ENERGY APPLICATIONS-A REVIEW

Research paper thumbnail of The Effect of Decahydronaphthalin on the Mechanical Properties of Montmorillonite Reinforced Polypropylene Nanocomposites

Research paper thumbnail of The corrosion behaviour of WC-VC-Co hardmetals in acidic media

Research paper thumbnail of Synthesis and Characterization of Hydroxyapatite- (HAP-) Clay Composites and Adsorption Studies on Methylene Blue for Water Treatment

Journal of Chemistry, 2021

Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be r... more Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be removed to get clean water. Hydroxyapatite (HAP) was synthesized from eggshells using the wet precipitation process. The as-synthesized HAP was characterized using Fourier Transform Infrared (FTIR) and X-ray powder diffraction (XRD). The synthesized HAP was mixed with three different clays: halloysite (HNT), kaolinite (KAO), and bentonite (BENT). The removal efficiency values of methylene blue (MB) from the data showed that HAP-BENT adsorbents had higher values, followed by HAP-HNT and then HAP-KAO adsorbents. The combined masses of 24 mg, 34.5 mg, and 33 mg (representing 20%, 15%, and 10% of HAP-BENT mass) had average adsorption capacity values of 20.7 mg/g, 17.2 mg/g, and 17.9 mg/g, respectively. For each mass percentage, the adsorption capacity values were found to decrease with adsorbent dosage. The HAP-BENT composites had removal efficiency values of 98.4, 91.9%, and 91.9%, respectiv...

Research paper thumbnail of Application of clay ceramics and nanotechnology in water treatment: A review

Research paper thumbnail of Corrosion ofWC-VC-Co Hardmetal in Neutral Chloride ContainingMedia

1 Council for Scienti�c and Industrial Research �CSIR�,Materials Science andManufacturing, P�O� B... more 1 Council for Scienti�c and Industrial Research �CSIR�,Materials Science andManufacturing, P�O� Box 3�5, Pretoria 0001, SouthAfrica DST/NRF Centre of Excellence in Strong Materials, and School of Chemical and Metallurgical Engineering, University of Witwatersrand, Johannesburg, Wits 2050, South Africa Materials Science and Engineering Department, University of Ghana, Legon, Accra, Ghana 4 School of Research, Enterprise and Innovation, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK 5 School of Science and the Environment, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK 6 School of Chemistry, University of the Witwatersrand, Johannesburg, Private Bag X3, Wits 2050, South Africa

Research paper thumbnail of Comparison of testing of susceptibility to solidification cracking of ferritic stainless steels using two methods

Research paper thumbnail of Solidification cracking susceptibility of ferritic stainless steels using Modified Varestraint Transvarestraint (MVT) method

Sādhanā

The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification c... more The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification cracking susceptibility of an unstabilised, a Nb-stabilised and two (Ti ? Nb) dual-stabilised ferritic stainless steels. Two different welding speeds of 6 and 3 mm/s using autogenous gas tungsten arc welding were employed. At the welding speed of 6 mm/s, the high-content (Ti ? Nb) steel was resistant and the Nb-stabilised steel was marginally susceptible to solidification cracking. At the welding speed of 3 mm/s, the Nb and the high (Ti ? Nb) steels were found to be marginally susceptible to solidification cracking while the unstabilised and low-content (Ti ? Nb) grades were resistant to solidification cracking. The weld metal microstructures transverse to the welding direction revealed columnar grains in all the samples for both welding speeds. The ferritic stainless steels were generally resistant to solidification cracking, except the Nb-stabilised steel, which was marginally susceptible to solidification cracking.

Research paper thumbnail of Solidification cracking susceptibility of ferritic stainless steels using Modified Varestraint Transvarestraint (MVT) method

Sādhanā

The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification c... more The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification cracking susceptibility of an unstabilised, a Nb-stabilised and two (Ti ? Nb) dual-stabilised ferritic stainless steels. Two different welding speeds of 6 and 3 mm/s using autogenous gas tungsten arc welding were employed. At the welding speed of 6 mm/s, the high-content (Ti ? Nb) steel was resistant and the Nb-stabilised steel was marginally susceptible to solidification cracking. At the welding speed of 3 mm/s, the Nb and the high (Ti ? Nb) steels were found to be marginally susceptible to solidification cracking while the unstabilised and low-content (Ti ? Nb) grades were resistant to solidification cracking. The weld metal microstructures transverse to the welding direction revealed columnar grains in all the samples for both welding speeds. The ferritic stainless steels were generally resistant to solidification cracking, except the Nb-stabilised steel, which was marginally susceptible to solidification cracking.

Research paper thumbnail of Corrosion of WC-VC-Co Hardmetal in Neutral Chloride Containing Media

ISRN Corrosion, 2013

ABSTRACT The effect of varying VC content on the corrosion behavior of WC-10 wt% Co hardmetals in... more ABSTRACT The effect of varying VC content on the corrosion behavior of WC-10 wt% Co hardmetals in sodium chloride (NaCl) and synthetic mine water (SMW) solutions has been investigated using anodic polarization scans and surface analytical methods. It is shown that the polarization behavior is active-pseudopassive in NaCl and active in SMW regardless of the VC content, while the corrosion resistance is poorer and independent of VC content in NaCl but better at high VC contents in SMW. The corrosion behavior of samples is explained using the effect of VC on the chemical composition of the binder.

Research paper thumbnail of Concrete Rebar Corrosion Inhibitors - A Review of Sustainable Natural Inhibitors

Sustainable Education and Development – Making Cities and Human Settlements Inclusive, Safe, Resilient, and Sustainable, 2022

Research paper thumbnail of Investigation of formation of precipitates and solidification temperatures of ferritic stainless steels using differential scanning calorimetry and Thermo-Calc simulation

The phase transformations in unstabilized and stabilized ferritic stainless steels during solidif... more The phase transformations in unstabilized and stabilized ferritic stainless steels during solidification were studied using Thermo-Calc and differential scanning calorimetry (DSC). The solidus and liquidus temperatures of the Thermo-Calc simulations were compared to the liquidus and solidus temperatures measured with DSC. Thermo-Calc software revealed the precipitates of the ferritic stainless steels to be MnS, TiN, Ti4C2S2, NbC, and Ti(C,N). Given the low volume fraction of precipitates, DSC could not be used to reveal the onset of precipitation. There was reasonable correlation between the liquidus and the solidus temperature, as calculated using Thermo-Calc and as measured using DSC. Generally, a higher niobium content resulted in a higher solidification temperature range.

Research paper thumbnail of Potential Application of Dioctyl Sodium Sulfosuccinate Salt (DOSS)–Saponin Binary Dispersant in Oil Spill Remediation: Synergistic Interaction Between DOSS and Saponin

Water, Air, & Soil Pollution, 2020

The interfacial activity of dispersants can be enhanced by combining two or more surfactants to f... more The interfacial activity of dispersants can be enhanced by combining two or more surfactants to formulate the dispersant. This paper examines the effects of Bio-Saponin (BS), a phytogenic surfactant on the interfacial activity of synthetic dioctyl sulfosuccinate sodium salt (DOSS) usually adopted as a suitable surface-active agent in dispersants used in dealing with large-scale oil spills. The o/w emulsion created with the binary DOSS-BS was very stable and recorded the least average droplet size compared with that of DOSS only and BS only. Lower surface and interfacial tension values were also obtained from the DOSS-BS binary formulation. The dispersion effectiveness was also higher compared with that of DOSS and BS. However, they were dependent on the salinity and type of crude oil. These observations were attributed to the moderation of the interaction between the anionic head group of DOSS by the polysaccharide hydrophilic group of BS. The results revealed the potential application of DOSS-BS binary dispersant in oil spill remediation and in other processes that would require an effective emulsifier.

Research paper thumbnail of The influence of Ti and Nb on solidification cracking of ferritic stainless steels, as determined using self-restrained samples

Welding in the World, 2019

We investigate precursors of an excited state quantum phase transition in the quasienergy spectru... more We investigate precursors of an excited state quantum phase transition in the quasienergy spectrum of the kicked top. Using a semiclassical approach, we analytically obtain a logarithmic divergence in the density of states, which is a hallmark of a continuous excited state quantum phase transition. We propose a protocol to observe the cusp behavior of the magnetization close to the critical quasienergy.

Research paper thumbnail of Physico-mechanical properties of bauxite Residue-clay bricks

Research paper thumbnail of NANOSTRUCTURED TiO2 AND THEIR ENERGY APPLICATIONS-A REVIEW

Research paper thumbnail of The Effect of Decahydronaphthalin on the Mechanical Properties of Montmorillonite Reinforced Polypropylene Nanocomposites

Research paper thumbnail of The corrosion behaviour of WC-VC-Co hardmetals in acidic media

Research paper thumbnail of Synthesis and Characterization of Hydroxyapatite- (HAP-) Clay Composites and Adsorption Studies on Methylene Blue for Water Treatment

Journal of Chemistry, 2021

Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be r... more Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be removed to get clean water. Hydroxyapatite (HAP) was synthesized from eggshells using the wet precipitation process. The as-synthesized HAP was characterized using Fourier Transform Infrared (FTIR) and X-ray powder diffraction (XRD). The synthesized HAP was mixed with three different clays: halloysite (HNT), kaolinite (KAO), and bentonite (BENT). The removal efficiency values of methylene blue (MB) from the data showed that HAP-BENT adsorbents had higher values, followed by HAP-HNT and then HAP-KAO adsorbents. The combined masses of 24 mg, 34.5 mg, and 33 mg (representing 20%, 15%, and 10% of HAP-BENT mass) had average adsorption capacity values of 20.7 mg/g, 17.2 mg/g, and 17.9 mg/g, respectively. For each mass percentage, the adsorption capacity values were found to decrease with adsorbent dosage. The HAP-BENT composites had removal efficiency values of 98.4, 91.9%, and 91.9%, respectiv...

Research paper thumbnail of Application of clay ceramics and nanotechnology in water treatment: A review

Research paper thumbnail of Corrosion ofWC-VC-Co Hardmetal in Neutral Chloride ContainingMedia

1 Council for Scienti�c and Industrial Research �CSIR�,Materials Science andManufacturing, P�O� B... more 1 Council for Scienti�c and Industrial Research �CSIR�,Materials Science andManufacturing, P�O� Box 3�5, Pretoria 0001, SouthAfrica DST/NRF Centre of Excellence in Strong Materials, and School of Chemical and Metallurgical Engineering, University of Witwatersrand, Johannesburg, Wits 2050, South Africa Materials Science and Engineering Department, University of Ghana, Legon, Accra, Ghana 4 School of Research, Enterprise and Innovation, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK 5 School of Science and the Environment, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK 6 School of Chemistry, University of the Witwatersrand, Johannesburg, Private Bag X3, Wits 2050, South Africa

Research paper thumbnail of Comparison of testing of susceptibility to solidification cracking of ferritic stainless steels using two methods

Research paper thumbnail of Solidification cracking susceptibility of ferritic stainless steels using Modified Varestraint Transvarestraint (MVT) method

Sādhanā

The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification c... more The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification cracking susceptibility of an unstabilised, a Nb-stabilised and two (Ti ? Nb) dual-stabilised ferritic stainless steels. Two different welding speeds of 6 and 3 mm/s using autogenous gas tungsten arc welding were employed. At the welding speed of 6 mm/s, the high-content (Ti ? Nb) steel was resistant and the Nb-stabilised steel was marginally susceptible to solidification cracking. At the welding speed of 3 mm/s, the Nb and the high (Ti ? Nb) steels were found to be marginally susceptible to solidification cracking while the unstabilised and low-content (Ti ? Nb) grades were resistant to solidification cracking. The weld metal microstructures transverse to the welding direction revealed columnar grains in all the samples for both welding speeds. The ferritic stainless steels were generally resistant to solidification cracking, except the Nb-stabilised steel, which was marginally susceptible to solidification cracking.

Research paper thumbnail of Solidification cracking susceptibility of ferritic stainless steels using Modified Varestraint Transvarestraint (MVT) method

Sādhanā

The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification c... more The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification cracking susceptibility of an unstabilised, a Nb-stabilised and two (Ti ? Nb) dual-stabilised ferritic stainless steels. Two different welding speeds of 6 and 3 mm/s using autogenous gas tungsten arc welding were employed. At the welding speed of 6 mm/s, the high-content (Ti ? Nb) steel was resistant and the Nb-stabilised steel was marginally susceptible to solidification cracking. At the welding speed of 3 mm/s, the Nb and the high (Ti ? Nb) steels were found to be marginally susceptible to solidification cracking while the unstabilised and low-content (Ti ? Nb) grades were resistant to solidification cracking. The weld metal microstructures transverse to the welding direction revealed columnar grains in all the samples for both welding speeds. The ferritic stainless steels were generally resistant to solidification cracking, except the Nb-stabilised steel, which was marginally susceptible to solidification cracking.

Research paper thumbnail of Corrosion of WC-VC-Co Hardmetal in Neutral Chloride Containing Media

ISRN Corrosion, 2013

ABSTRACT The effect of varying VC content on the corrosion behavior of WC-10 wt% Co hardmetals in... more ABSTRACT The effect of varying VC content on the corrosion behavior of WC-10 wt% Co hardmetals in sodium chloride (NaCl) and synthetic mine water (SMW) solutions has been investigated using anodic polarization scans and surface analytical methods. It is shown that the polarization behavior is active-pseudopassive in NaCl and active in SMW regardless of the VC content, while the corrosion resistance is poorer and independent of VC content in NaCl but better at high VC contents in SMW. The corrosion behavior of samples is explained using the effect of VC on the chemical composition of the binder.