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Synthesis and characterization of silver Nanoparticle elecrocatalyst embedded onto indium tin oxide electrodes for degradation of azo dyes
(Mount Kenya University, 2025-11-05) Osemba,Martin Ouma; Muriuki,Mary; Karenga,Samuel
The research was conducted to establish the effectiveness of silver nanoparticles embedded on indium tin oxide (ITO) thin film conducting material in causing the textile azo dyes effluent degradation. The Overall Objective was to synthesize and characterize silver nanoparticles electrocatalyst embedded on indium tin oxide for the degradation of azo dye in the textile effluent. The 40.0 g of powdered crab shells resulted in 23.0g of chitin after demineralization and 7.2 g (31.3 %) of chitosan. Chitosan obtained from crab shells exhibited 89.5% degree of deacetylation showing efficiency in reduction and stabilization of silver nanoparticles from the Ag+ ions. The UV-Vis spectroscopy showed the formation of spectra with λmax at 420 nm. The scanning electron microscope (SEM) depicted nanoparticles showing spherical morphology with size range of 50 nm. FTIR signals were recorded at 1658 cm−1 corresponding to the amide (C=O) bonds, at 1089 cm−1 representing secondary alcohol (C-O-C) bonds at 564 cm−1 plane with bends NH, plane-out and bends C−O. C-H stretching vibrational signal was noted at 2927 cm−1, a broader band at 3426 cm−1 for an overlap between the O−H stretching vibration and the N−H stretching vibration of the oligosaccharide applied in the capping. The intensity of the O−H and N−H stretching bands emanated from the hydroxyl and amino groups thus shifting to 3426 cm−1, implying that chelation of silver with both O−H and N−H groups of chitosan actually took place. The percentages of azo dyes degradation were as follow: 68.4%, 72.5% and 93.1% using electrocoagulation, ITO and ITO-AgNPs coupled electrodes respectively. The results obtained from the two factors ANOVA with replication indicated significant difference (p= 0.0024) when the silver nanoparticles embedded on indium tin oxide electrodes were utilized in the degradation of these azo dyes in the effluent samples. In all the four samples it was noted that, 8 ppm of the silver nanoparticle concentration applied to the ITO thin film electrodes resulted in the least power consumption maximum of 0.4536 watts with average values of 0.0300±0.0023 hours and a current flow of 0.63 A. The average specific consumption of energy at 12 V was 2.110 kWh/m3 compared to 1.318 kWh/m3 at Pd of 24 V respectively. IR drop was minimized by lowering the created gap within the thin film electrodes to 0.2 cm and raising the surface area of the cross section of electrodes and specific solution conductance. The COD listing for the samples after treatment fell below 100 mg/L which is much lower than the acceptable limits of COD ≤250 mg/L. The BOD for dye effluent from the two-way ANOVA with replication portrayed a significant variation (p=0.0000238) when compared to the one of WHO 2002 with the range of 150±5 mg/L. The colour removal was 99.97% showing that, the optimized process was effective and efficient in the degradation of these azo dyes in
Production of Chitosan from Crab Shells
(Mount Kenya University, 2024-09-07) Osemba,Martin Ouma; Muriuki,Mary; Karenga,Samuel
The amino polysaccharide of chitin polymer happens to be the most
commonly known polymer. Chitosan as a derivative of chitin is
obtained through demineralization and deacetylation. Owing to the
special properties of chitin and chitosan for instance their bio compatibility, bio-biodegradability, non-toxicity and also capability
to form films, have resulted in their suitability in chemical and thermal
conductivity applications. In the field of nanotechnology, chitosan based materials are currently being widely applied. The purpose of
this review is to synthesize and characterize chitosan obtained from
the crab shells. The absorption band obtained from FTIR between
1220 cm−1 and 1020 cm−1 represented free amino group (−NH2).
The 40.000 grams of powdered crab shells resulted in the formation
of 23.000g of chitin after undergoing the process of demineralization
to eliminate the minerals available in the crab shells. The removed
minerals from the crab shells constituted 17.000 g (39.53%) of the
total dry weight in the crab shell. The water binding capacity (WBC)
was found to be 69 %.
Using ITO–Silver Nanoparticles with Electrocoagulation to Reduce Colour, COD, and BOD in Textile Wastewater
(Mount Kenya University, 2025-12-05) Osemba,Martin; Maghanga,Justin
This study developed a material made from indium
tin oxide and silver nanoparticles to improve the
electrocoagulation process used for cleaning textile
wastewater. The material was made through chemical
reduction and examined using SEM, TEM, XRD, and BET
tests. The results showed that the silver particles were evenly
spread on the ITO surface with sizes between 20 and 50
nanometers. The crystal structure confirmed that both ITO and
silver were successfully combined. The surface area was high,
which helps reactions take place more easily. The material was
then used as an electrode in an electrocoagulation system to
treat real textile wastewater. The wastewater had very high
levels of colour, COD, and BOD. The best results were
achieved at a current density of 25 mA per square centimeter, a
pH of 5, and 20 minutes of treatment. Under these conditions,
the system removed 97 percent of the colour, 89 percent of
COD, and 92 percent of BOD. These results were possible
because the ITO and silver worked together to improve charge
movement and help break down dye molecules. The study
shows that this method is effective, sustainable, and suitable
for large-scale use in textile wastewater treatment.
Chitosan Coupled Silver Nanoparticles Electrocatalyst Synthesis and Characterization
(Mount Kenya University, 2024-09-25) Osemba,Martin; Muriuki,Mary; Karenga,Samuel; Keru,Godffrey
This study sought to find a suitable technique for synthesizing and
characterizing silver nanoparticles due to its applications in various fields such
as nanotechnology and medical. The synthesized silver nanoparticles were
characterized using SEM microscopy, FT-IR and UV-Vis spectroscopy. The
maximum absorbance from the UV-Vis spectrophotometer showed the
formation of silver nanoparticles with λ max of 418 nm. The FTIR analysis
envisaged a strong symmetrical stretching at 1400 cm-1 to 1200 cm-1 with the
major peaks recorded at 1390 cm-1 and 1380 cm-1, indicating the presence of
nitro components in the sample. The signal at 1658 cm−1 corresponded to the
amide (C=O) bonds stretching vibrations, at 1089 cm−1 C-O-C bonds and at
564 cm−1 plane with bends NH, plane-out and bends C−O. C-H stretching
vibrational signal was noted at 2927 cm−1, and a broader band at 3426 cm−1
with an overlap between the O−H stretching vibration and N−H stretching
vibration of the oligosaccharide applied in the capping. The concentration of
chitosan on transmittance was done using 0.5%, 1.0%, 1.5% and 2.0% solutions
with the results from FT-IR showing elaborate intensity at 2.0 % chitosan
capping and the least at 0.5 %. Scanning microscope validated characterized
silver nanoparticles morphology at 500nm. The results obtained from SEM
depicted a size range of 100 nm with resolutions between 0.5 to 4 nm
Electrochemical Colour Removal of Azo Dyes Using Boron-Doped Diamond Electrodes and Silver Nanoparticles as Electrocatalyst
(Mount Kenya University, 2024-09-19) Osemba,Martin Ouma; Ojwang,Loice; Maghanga,Justin
Azo dyes are carcinogenic and if taken would lead to debilitating adverse health effects
in animals, man and aquatic organisms. In this study, novel Boron Doped Diamond
(BDD) electrodes coated with silver nanoparticles were applied. Iron (11) sulphate
was used as a supporting electrolyte and silver nanoparticles as electrocatalyst to
enhance the degradation efficiency. Degradation efficiency was monitored by UV VIS spectrometry while some of the physico-chemical parameters were determined
by standard methods for examination of water and wastewater as outlined in the
APHA (2000). The absorption spectra for the four dyes were determined and their λ
max ranged between 470 to 590 nm in UV-VIS spectrum. Colour removal of 100%
was achieved at the end of the electrochemical degradation. The colour levels of the
treated textile wastewater were found to be BDL. The final treated wastewater was
compared with National Environmental Management Authority (NEMA) and World
Health Organization (WHO) effluent discharge standards for the possibility of re-use
or direct discharge to a natural water course. From the study findings, it is evident that
the concentration of the dyes considered efficient for colour removal was 10 ppm since
there was less power consumption thus economical. An increased concentration from
0.1 to 0.5 g/l of FeSO4 was added to act as a supporting electrolyte to enhance quick
removal of the dye. As the concentration of silver nanoparticles increased from 0 to 8
ppm lowest power of 0.4536 watts within the group mean value of 0.03±0.0023 time
(hours) and 0.63±0.0001 current (amperes) was recorded. Therefore, it was concluded
that a greater concentration of AgNPs acted effectively as the electrocatalyst to
eliminate the barrier during the dye removal process. In all four experiments using
different kinds of textile dyes, it was worth noting that an increase in the inter electrode distance from 2mm to 8 mm led to a decrease in the current production from
1.23±0.0140 A - 0.58±0.0048 A which resulted to a lot of time taken from
0.025±0.0012 hr -0.723±0.0047 hr. The aspect of temperature was also considered
under the above optimal conditions, and at 45ºC the removal was faster as there was
an increase in the chemical kinetics of the particles in the reaction system. As the pH
increased from 4.0 to 7.0, current production increased from (0.21±0.0005-
0.24±0.0014 A). From the group, analyzed pH range of 6.5±¬0.5 was noted to enhance
better removal of the studied azo dye from the textile wastewater effluent. The textile
azo dye colour was removed to below detectable levels (BDL) and thus could not be
detected by human eye after treatment.
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