1,363 research outputs found
Synthesized af-PFCl and GG-g-P(AN)/TEOS hydrogel composite used in hybridized technique applied for AMD treatment
No full textIn the present study af-PFCl, GL-g-P(AN) hydrogel and GL-g-P(AN)/TEOS hydrogel composite were synthesized. The hydrogels were characterized using the fourier transformed infra-red (FTIR) and the scanning electron microscope (SEM) techniques. The coagulant af-PFCl and the hydrogels were applied consecutively in flocculation and adsorption processes respectively for the treatment of acid mine drainage (AMD). It was observed that the grafting process increased the amount of binding groups on the hydrogels. The hybridization of the techniques assisted in the removal of anions; while the cations were mostly removed by the adsorption process. The adsorbents behaviour was fittingly expressed by the pseudo-second order model. The adsorption capacities of GL-g-P(AN)/TEOS hydrogel composite for the removal of Al, As and Zn were 3.89, 0.66 and 0.394 respectively; while the adsorption capacities of GL-g-P(AN) for the removal of Al and Mg were 3.47 and 9.66 mg/g respectively.
The techniques applied in this study have shown good potential for the removal of specific pollutants from the AMD; it is however, important that the appropriate hybridization of techniques allows to remove all the pollutants and restore acceptable water qualit
Prospects for immobilization of microbial sorbents on carbon nanotubes for biosorption: bioremediation of heavy metals polluted water
No full textDetails the water research applications of nanotechnology in various areas including environmental science, remediation, membranes, nanomaterials, and water treatmen
Implication of plants and microbial metalloproteins in the bioremediation of polluted waters: a review
No full textTraditional approaches to municipal water monitoring barely includes procedures for toxic heavy metals
testing. However, the presence of such contaminants in water sources is expected in South African
surface and ground waters as a result of dispersion of effluents from acid mine drainage sites. Cheap
and eco-friendly methods using microorganisms and plants are discussed in this review. Metal uptake
mechanisms involving special proteins namely metalloproteins or metal-binding proteins and peptides,
are elaborated and supported with some examples. The potential of phytochelatins and metallothioneins
as metal chelating ligands in plants and microorganisms are reviewed and suggestion made to engineer
these peptides in microbial sorbents for improved metal uptake. This review covers a number of
approaches in the bioremediation of metal polluted effluents and systematically explains the mechanisms
involved in the bio-uptake of metals, while highlighting the contribution of metal-binding
protein
Adaptation behaviour of bacterial species and impact on the biodegradation of biodiesel-diesel
No full textTwo bacteria, namely Bacillus subtilis and Pseudomonas aeruginosa were exposed to different concentrations of diesel to increase their adaptation to the fossil fuel, and were used for the degradation of diesel-biodiesel blends. The biodegradation rate was evaluated using the redox indicator 2,6-dichlorophenol indophenol (DCPIP) test and gravimetric analysis. The preliminary exposure of cells to diesel proved to improve their biodegradation capacities, and exposure to a higher concentration (70%) of diesel resulted in maximum biodegradation of up to 58.38 g and 1.78 g of degraded oil per CFU/mL (1010) for P. aeruginosa and B. subtilis respectively. It was found that the adapted cells preferably used diesel in the blend. P. aeruginosa and B. subtilis exhibited different adaptation capabilities and biodegradation behaviour. Biodiesel stimulated the biodegradation of the diesel-biodiesel blends by non-adapted cells only; the adapted cells exhibited a different behaviou
Evaluation of the antibacterial activity of metal impregnated multi-walled carbon nanotubes: impact of domestic wastewater as supporting medium
No full textDespite the availability of potential water treatment resources, bacterial infections are still of major
concern, especially in developing countries where large numbers of people do not have access to
clean and safe water. Nanotechnology offers great possibilities in the field of wastewater treatment
for its potency against pathogenic bacteria. This study focuses on the antimicrobial activity of three
different nano-metals (silver, copper oxide, and zinc oxide) and the additive effect when they are
used in the presence of functionalized multi-walled carbon nanotubes (MWCNTs) against four com
-
monly found domestic wastewater bacterial strains. The bacteria studied included Gram-positive
bacteria (
Bacillus subtilis
and
Staphylococcus aureus
) and Gram-negative bacteria (
Salmonella typhi
and
Escherichia coli
). Silver nanoparticles (Ag NPs) were the most potent antibacterial agent reducing up to
60.78% ± 8.33% and 63.26% ± 2.12% growth of Gram-positive and Gram-negative bacteria, respectively.
The effectiveness increased to 96.66% ± 1.99% against Gram-positive bacteria and 94.59% ± 1.39%
against Gram-negative bacteria when the MWCNT was decorated with Ag NPs, due to the improved
surface area of the synthesized complex. Additionally, it was found that the inactivation of bacteria
by nanomaterials was species-specific, with Gram-negative
E. coli
showing the strongest overall resis-
tance. The overall antibacterial effect of the synthesized compounds was stronger in real wastewater
solutions while the nutrients enriched media allowed more prominent growth and bacteria recover
Clayey materials in river basin enhancing microbial contamination of river water
No full textMineral constituents of clay materials may promote interaction, adsorption and attachment of microorganisms,
often resulting in biofilms’ formation. In this study investigation is made to determine how littoral
clayey materials on the shores of a river promote accumulation of bacteria and increase
contamination of river water. Clayey samples were collected at various points along the shore of a river
around Mondeor in Johannesburg and the mineralogical composition was determined using XRD and
XRF. Microorganisms in clay-biofilm and river water were identified by DNA sequencing and plate count.
Results showed that total coliforms, Escherichia coli, Pseudomonas sp. and presumptive indigenous microorganisms
attached to littoral clayey materials containing the mineral muscovite (characterising argillaceous
soils). Bacteria number on clayey materials was significantly higher than on overlying water
especially before rainy season. However a decrease of the number of bacteria in clayey materials concurrent
with an increase in the number of suspended bacteria after rain events, was the result of the action of
high and fast flows in the basin, eroding the biofilms. Attachment of microorganisms in clayey material as
observed in this study could be ascribed to the glue-like aspect of soil (due to muscovite) that facilitates
adhesion. It therefore demonstrates the potential of clayey materials to encourage biofilm formation and
enhance microbial contamination of river water as shown her
Removal of malachite green and toluidine blue dyes from aqueous solution using a clay-biochar composite of bentonite and sweet sorghum bagasse
No full textA clay-biochar composite was prepared through slow
pyrolysis of a mixture of bentonite clay and sweet sorghum
bagasse. The adsorption of cationic dyes, namely, toluidine
blue (TB) and malachite green (MG), by the clay-biochar
composite was investigated to determine the adsorption
mechanism and its sorption potential. Bentonite clay, sweet
sorghum biochar and the bentonite-biochar composite were
characterized through X-ray fluorescence (XRF), scanning
electron microscopy (SEM) and Fourier transform infrared
(FT-IR) analyses. For the adsorption study, the effects of
exposure time, initial dye concentration and temperature were
investigated. The findings clearly illustrated the complex
physico-chemical properties of the clay-biochar composite
encompassing distinct features of bentonite clay and biochar,
therefore confirming successful preparation. The adsorption of
MG was found to occur on a heterogeneous surface as
predicted by the Freundlich isotherm model, while the
adsorption of TB occurred mostly at a monolayer surface
described by the Langmuir isotherm model. The adsorption
equilibrium data was best described by the pseudo-second
order kinetic model for all adsorbents. The estimated
adsorption capacity of the clay-biochar composite (12.1255
mg/g for MG and 9.9356 mg/g for TB) suggests improved
adsorption capacity of the biochar after incorporation of clay.
The thermodynamic study revealed that the adsorption of dyes
was mostly a spontaneous and exothermic process.
The adsorbent investigated in this study showed good
potential for the removal of cationic dyes from aqueous
solution and could be considered for the remediation of water
polluted by industrial effluent
Photocatalytic Degradation of Azo and Rhodamine Dyes Using Copper (II) Oxide Nanoparticles
No full textFresh water pollution by dyes from various
industries is raising a lot of concern lately. Despite their
well-known toxicity to humans, azo dyes make up over half of the
used dye population. Rhodamines are also a well-used class of dyes
in industry. This study employed a cost effective, energy efficient,
environmentally benign method to degrade Methyl Orange
(MeO), Methylene Blue (MB) and Rhodamine B (RhB) dyes. The
photocatalyst used was copper (II) oxide (CuO) nano-sized
particles synthesised from CuSO4
.5H2O, Cu(NO3
)2
.3H2O and
NaOH via a simple solution route with neither a catalyst, template
nor a surfactant. The nanoparticles were characterised and used
for the photocatalytic degradation of the above dyes in the
presence of H2O2
. The CuO nanoparticles synthesised from both
copper precursors were found to degrade all dyes effectively over
the same degradation time interval, recording an overall minimum
degradation efficiency of 85 % and maximum of 99 %
Hydrogel-based bioflocculants for the removal of organic pollutants from biodiesel wastewater
No full textHydrogel based bioflocculants namely Gelatin and acrylic acid-co-acrylamide [GL-cl-P(AA-co-AAM)] and hybrid hydrogel composite with good adsorption potential, were synthesized in this study for the treatment of biodiesel wastewater. The two hydrogels were characterized using X-Ray diffraction, Fourier transformed infra-red spectroscopy and scanning electron microscope. It was found that the synthesis provided the composite with the functional groups of the individual components. The hydrogels were found to achieve around 65 % of BOD removal and exhibited a maximum performance at a dosage 12.5 mg/L. The kinetic studies of the removal of BOD by all the hydrogels were found to follow the pseudo-second order kinetic model; the adsorption capacities of the GL-cl-P(AA-co-AAM) and the hybrid hydrogel composite were 11,368.8 and 12,787 mg/g, respectively. The flocs formed by the hybrid hydrogel composite and polyferric chloride were also more stable than those formed by the GL-cl-P(AA-co-AAM) and MgOH; implying that the incorporation of the attapulgite into the composite had resulted in the development of a better coagulant. The viability of the application of the hybrid hydrogel composite for the treatment of biodiesel wastewater could therefore be further investigated at pilot scale to prepare the implementation at large scal
Soil quality in the basin of mine effluents and the potential of alleviation of metal dispersion
No full textThe soils along the basin ofmine effluent were investigated for their role in the mitigation of the
pollution of river water in the residential areas around Potchefstroom in South Africa.The results showed that the
soils were mainly semi-permeable soil (K from 5.96 ×10-6 to 1.26 ×10-5 m/s) and the cation exchange potential
(CEC) values(19.3 to 38.5 cmol/kg)were indicative of the presence of clays in the soils. Investigation of the
adsorption potential of soils showed that they had higher affinity for Cu compared to Ni and Zn, and bottom soils
were better adsorbents than the top soils. Clayey material in soils along the mine effluent basin enhances
interaction with metals, contributing to the mitigation of water pollutio
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