Investigation of the Effect of a Flocculent of Bentonite Clay with MgCO3 in Synthetic Acid Mine Drainage (AMD) Treatment

Effect of a flocculent of bentonite clay with MgCO3 in Synthetic AMD was investigated in present study. The AMD samples were collected from the western decant in Krugersdorp, South Africa was modified by adding arsenic, zinc and cobalt. The pH, conductivity, dissolved oxygen (DO), oxygen reduction potential (ORP) and turbidity were measured. Those samples were treated with bentonite clay, MgCO3 and a flocculent of bentonite clay and MgCO3 respectively in a jar test, employing either rapid or slow mixing. Results showed that the conductivity of the samples with increasing bentonite clay while keeping MgCO3 constant decreased with increasing dosage, which was attributed to adsorption of the ions onto the negative sites of the porous bentonite when ionic strength increased. The oxygen content of the DO and ORP was not influenced by the rate of mechanical agitation, i.e. rapid and slow mixing respectively. Destabilization-hydrolysis was not influenced by the pH but the ionic strength of the colloidal AMD suspension, valence and electronegative of the metal ions. Turbidity removal of the synthetic flocculent used occured through physico-chemical phenomenon (SEM micrographs) and charged porous bentonite clay. In conclusion: Bentonite clay controls equilibrium state of the ionic strength of the system through adsorption of excess ions added to the system. Velocity gradient induced by mechanical agitation does not have an influence on the turbidity removal. Keywords: wastewater, coagulants, AMD, mixing, shaking, turbidit

Determination of the Efficiencies of Clay and PFCL or PACL with Na2CO3 Flocculent in the Removal of TSS from the AMD

Abstract: The experiment was conducted on the acid mine drainage (AMD) that was sampled from the Krugersdorp decant in South Africa. Five 500 ml glass beakers were filled with 200 ml of AMD sample and dosed with synthetic flocculent of FeCl3 and Na2CO3 (PFCl) and treated in jar test (exp. A). pH, conductivity, total suspended solids (TSS), dissolved oxygen (DO) and oxidation reduction potential (ORP) were measured after treatment and an hour settling. Another identical set of experiments was carried out with a combination of clay and PFCl dosage (exp. B). A third similar set of experiments was conducted with dosages of a combination of clay with PFCl or clay with AlCl3 and Na2CO3 (PACl) including another set of experiments using five 500 ml Erlenmeyer flasks in a shaker (exp. C). The pH results of the samples dosed with PFCl are relatively lower than that of the samples with a combination of clay and PACl dosage. The pH changing pattern with PFCl exhibited an increasing rate with increasing dosage whereas the pH of the sample dosed with a combination of clay and PFCl decreases with increasing dosage. The results show that bentonite clay does not have significant impact on pH of the samples. The ORP in treated AMD samples of experiments A and B is lower than in raw AMD sample. Residual TSS of the AMD samples which were treated with mixing are similarly identical to those of the samples treated on a shaker. TSS removal of the AMD samples with clay and PFCl is better than that with FeCl or PACl only

Review: BTEX compounds in water – future trends and directions for water treatment

BTEX (benzene, toluene, ethylbenzene, and xylene) compounds are common water  resource and potable water pollutants that are often left undetected and untreated by  municipal treatment systems in spite of the negative repercussions associated with their ingestion. The US EPA has classified these pollutants as priority pollutant, yet  they are persistently present in a variety of water resources. In this review paper, we highlight the sources and reported concentrations of BTEX compounds in water and explore historical remediation techniques that have been applied such as  bioremediation and natural attenuation. We also highlight emerging possibilities and future directions for remediation techniques, such as nanotechnology-based materials and novel green materials (tannins) that can be applied to ensure removal of these  compounds in water. Keywords: adsorbents, biosorbents, BTEX, remediation, nanotechnology, water qualit

BTEX compounds in water – future trends and directions for water treatment

Abstract: BTEX (benzene, toluene, ethylbenzene, and xylene) compounds are common water resource and potable water pollutants that are often left undetected and untreated by municipal treatment systems in spite of the negative repercussions associated with their ingestion. The US EPA has classified these pollutants as priority pollutant, yet they are persistently present in a variety of water resources. In this review paper, we highlight the sources and reported concentrations of BTEX compounds in water and explore historical remediation techniques that have been applied such as bioremediation and natural attenuation. We also highlight emerging possibilities and future directions for remediation techniques, such as nanotechnology-based materials and novel green materials (tannins) that can be applied to ensure removal of these compounds in water

Parametric optimization of the production of cellulose nanocrystals (CNCs) from South African corncobs via an empirical modelling approach

In this study, cellulose nanocrystals (CNCs) were obtained from South African corncobs using an acid hydrolysis process. The delignification of corncobs was carried out by using alkali and bleaching pretreatment. Furthermore, the Box-Behnken Design (BBD) was used as a design of experiment (DOE) for statistical experimentations that will result in logical data to develop a model that explains the effect of variables on the response (CNCs yield). The effects (main and interactive) of the treatment variables (time, temperature, and acid concentration) were investigated via the response methodology approach and the obtained model was used in optimizing the CNCs yield. Surface morphology, surface chemistry, and the crystallinity of the synthesized CNC were checked using scanning electron microscopy (SEM), a Fourier Transform Infra-red spectroscopy (FTIR), and an X-ray diffraction (XRD) analysis, respectively. The SEM image of the raw corncobs revealed a smooth and compact surface morphology. Results also revealed that CNCs have higher crystallinity (79.11%) than South African waste corncobs (57.67%). An optimum yield of 80.53% CNCs was obtained at a temperature of 30.18 °C, 30.13 min reaction time, and 46 wt% sulfuric acid concentration. These optimized conditions have been validated to confirm the precision. Hence, the synthesized CNCs may be suitable as filler in membranes for different applications.Global Excellence Status (GES), University of Johannesburg.http://www.nature.com/scientificreportsam2023Chemical Engineerin

Hydrogen and Carbon Nanotubes from Pyrolysis-Catalysis of Waste Plastics: A Review

More than 27 million tonnes of waste plastics are generated in Europe each year representing a considerable potential resource. There has been extensive research into the production of liquid fuels and aromatic chemicals from pyrolysis-catalysis of waste plastics. However, there is less work on the production of hydrogen from waste plastics via pyrolysis coupled with catalytic steam reforming. In this paper, the different reactor designs used for hydrogen production from waste plastics are considered and the influence of different catalysts and process parameters on the yield of hydrogen from different types of waste plastics are reviewed. Waste plastics have also been investigated as a source of hydrocarbons for the generation of carbon nanotubes via the chemical vapour deposition route. The influences on the yield and quality of carbon nanotubes derived from waste plastics are reviewed in relation to the reactor designs used for production, catalyst type used for carbon nanotube growth and the influence of operational parameters

Adsorption of BTEX compounds from water using green-synthesized iron nanoparticles

Abstract: Please refer to full text to view abstract