Peer Reviewed Articles
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/38
2024-03-29T12:49:11ZPassive sampling: An effective method for monitoring seasonal and spatial variability of dissolved hydrophobic organic contaminants and metals in the Danube river
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7717
Passive sampling: An effective method for monitoring seasonal and spatial variability of dissolved hydrophobic organic contaminants and metals in the Danube river
Vrana, Branislav; Klucárová, Veronika; Benická, Eva; Abou-Mrad, Ninette; Amdany, Robert; Horáková, Sona; Draxler, Astrid; Humer, Franko; Gans, Oliver
Application of passive samplers is demonstrated for assessment of temporal and spatial trends of dissolved
polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and priority metals in
the middle stretch of the Danube river. Free dissolved concentrations of PAHs, measured using SPMD
samplers, ranged from 5 to 72 ng L
. Dissolved PCBs in water were very low and they ranged from 5 to
16 pg L
1
1
. Concentration of mercury, cadmium, lead and nickel, measured using DGT samplers, were
relatively constant along the monitored Danube stretch and in the range <
0.1, <
1e20, 18e74, and 173
e544 ng L
Keywords:
Danube
Free dissolved concentration
Persistent organic pollutants
Metals
Passive sampling
, respectively. Concentrations of PAHs decreased with increasing temperature, which reflects
the seasonality in emissions to water. This has an implication for the design of future monitoring programs
aimed at assessment of long term trends. For such analysis time series should be constructed of
data from samples collected always in the same season of the year.
2013-08-23T00:00:00ZInvestigating the temporal trends in PAH, PCB and OCP concentrations in Hartbeespoort Dam, South Africa, using semipermeable membrane devices (SPMDs)
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7715
Investigating the temporal trends in PAH, PCB and OCP concentrations in Hartbeespoort Dam, South Africa, using semipermeable membrane devices (SPMDs)
Amdany, Robert; Chimuka, Luke; Cukrowska, Ewa; Kukučka, Petr; Kohoutek, Jiří; Vrana, Branislav
The seasonal variability of persistent organic pollutants in Hartbeespoort Dam, South Africa, was investigated using
emipermeable membrane devices (SPMDs) as passive samplers. Freely dissolved waterborne polycyclic aromatic
hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were sampled to investigate
easonal changes in their concentrations. Exposure of the passive samplers was done for 14 days at the same sampling site in
ach of the four seasons of the year, in 2011. The SPMD-derived analyte amounts enabled the calculation of time-weighted
averages of free dissolved waterborne levels of the contaminants. Concentrations ranged from 30.0 ng∙ℓ
-1
to 51.5 ng∙ℓ
-1
for
PAHs, 38 pg ℓ
-1
to 150 pg∙ℓ
-1
for PCBs, 9.2 to 10.4 ng∙ℓ
-1
for HCHs and 0.3 to 0.8 ng∙ℓ
-1
for DDTs, respectively. It was also
noted that the winter season generally exhibited higher contaminant concentrations for most compounds studied, which
ikely reflects the seasonality of their atmospheric deposition. An attempt was also made to identify possible sources of PAH
ontaminants in the dam by examining PAH ratios. These diagnostic ratios were inclined towards pyrogenic sources of
pollution, except for the winter season where both pyrogenic and petrogenic sources likely contribute to the contamination
pattern.
2014-05-06T00:00:00ZDetermination of naproxen, ibuprofen and triclosan in wastewater using the polar organic chemical integrative sampler (POCIS): A laboratory calibration and field application
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7712
Determination of naproxen, ibuprofen and triclosan in wastewater using the polar organic chemical integrative sampler (POCIS): A laboratory calibration and field application
Amdany, Robert; Chimuka, Luke; Cukrowska, Ewa
In this study, the occurrence in wastewater of two non-steroidal anti-inflammatory drugs (NSAIDs), naproxen and
ibuprofen, and one personal care product, triclosan, was assessed using the polar organic chemical integrative sampler
(POCIS). The samplers were initially calibrated in the laboratory to obtain sampling rates (Rs) for each target compound
followed by deployment in the influent and effluent of Goudkoppies and Northern Wastewater Treatment Plants (WWTPs),
South Africa. Exposure was done for 14 days in 2012. High performance liquid chromatography (HPLC) system with
ultraviolet (UV) and fluorescence (FLD) detectors was used to analyse POCIS extracts. Laboratory calibration of POCIS
yielded Rs values for the three compounds that were between 0.087 and 0.383 ℓ∙d
-1
in quiescent conditions, and 0.125 and
0.936 ℓ∙d
-1
in stirred conditions. From the accumulated amounts in field-deployed samplers, estimated freely dissolved
concentrations of the studied compounds in wastewater influent ranged from 55.0 to 78.4 μg∙ℓ
-1
and 52.3 to 127.7 μg∙ℓ
-1
in Goudkoppies and Northern WWTPs, respectively. Average concentrations of these compounds in the treated effluent
ranged from 10.7 to 13.5 μg∙ℓ
-1
in Goudkoppies WWTP, and 20.4 to 24.6 μg∙ℓ
-1
in Northern WWTP. Analyte removal
efficiencies varied between 68 and 86% in Goudkoppies WWTP and 61 and 82% in Northern WWTP. Grab samples
processed by SPE method yielded higher analyte concentrations (up to three-fold) as compared to POCIS-derived estimates.
This discrepancy was attributed to SPE’s ability to extract both the free dissolved, and particle sorbed fractions of the
contaminants.
2014-05-02T00:00:00ZResearch Advances in Oil Tanning Technology
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/4668
Research Advances in Oil Tanning Technology
Ongarora, Benson G.
The conventional process of chamois leather manufacturing for industrial applications utilizes fish oil which contains substantial amounts of pentadienoic fatty acid. The applications of chamois leathers include cleaning polished surfaces, manufacture of gloves and orthopedic uses. However, due to fish oil’s strong odor and high cost, considerable efforts have been made to counter these challenges. Esterification of fish oil has been used as a strategy to address the problem of odor and water absorption but this cannot solve the issue of cost. Oils from plant sources such as linseed, rubber, jatropha, castor and sunflower have been investigated as potential tanning substitutes for fish oil. Linseed has been found to produce chamois leather with mild odor and water absorption characteristics close to those of fish oil compared to other oils obtained from plant sources. Oil from goat fleshing has also been investigated in chamois leather production and has been found to produce chamois leather whose odor compares with that of linseed oil tanned leather. If these tanning oil alternatives are combined with other research advances in chamois leather production such as glutaraldehyde pre-tanning and oxidation using hydrogen peroxide or through ozonation, then the issue of cost, odor and long oxidation period can be resolved.
2021-01-01T00:00:00Z