Chemistry
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Item Polylactic acid (PLA) viscoelastic properties and their degradation compared with those of polyethylene(Academic Journals, 2015-10-19) Wanjiku Muthui, Zipporah; Kamweru, Paul; Nderitu F. G; Hussein S. A. Golicha; Ngumbu R.; Njoroge G. N.Polyethylene (PE) films are widely used in packaging. PE is a thermoplastic manufactured from nonrenewable petroleum resources. Due to its non–biodegradability, its films have posed serious pollution problems e.g. visual pollution, blockage of gutters and drains, choking of animals etc. Suitable replacements for PE films especially for single use only, are the starch based thermoplastics such as Polylactic acid (PLA) which are fully biodegradable. This paper reports a comparison of the viscoelastic properties of commercially obtained PLA and PE films, and the degradation of the same under a composting environment. The storage and loss moduli of PLA and PE films were determined using the Dynamic mechanical analyzer (DMA) model 2980. The elastic modulus of PLA was found to be 2222.87 MPa at 50˚C and amplitude of 10 μm. This is higher than that of PE which was found to be 236.69 MPa at the same temperature and amplitude. Analysis of composting samples over a time span of 36 days indicated a rapid loss of storage modulus of PLA with that of PE remaining fairly constant. Overall, the results suggest that PLA is a suitable substitute for PE in as far as technical performance and degradability is concerned.Item Concentration of Inorganic Contaminants in Shallow Borehole Water in Chuka Sub-County, Kenya(Journal of Chemical, Biological and Physical Sciences, 2020-11-24) Edith. M., Rugendo; Eric C., Njagi; Ochieng, OmbakaGroundwater from shallow aquifers is an important source of portable water in Chuka Sub-County. However, most shallow boreholes in Chuka Sub-County are undocumented and susceptible to contamination by both geogenic and anthropogenic activities. This study was conducted to evaluate the quality of shallow boreholes water in Chuka Sub-County. Samples were collected from twenty boreholes in Chuka Sub County during the dry and wet seasons. The temperature, pH and conductivity were determined in situ using a meter. The concentration of cations was determined using ICP-MS. The concentrations of anions were determined using standard APHA analytical methods. The temperatures and conductivities of borehole waters were within the limits set by KEBS and WHO. The pH of water in most boreholes during the wet season was within the limits set by KEBS and WHO for portable water. However, borehole water at Karandini (T15) was highly acidic (pH of 3.95) during the wet season. During the dry season, borehole waters were slightly acidic (4.42 - 6.44) except for the borehole at Ndagani market (T11), whose water was alkaline (pH = 8.75). The concentrations of trace and toxic cations and anions (NO3 - , SO4 2- , Cl and PO4 3- ) were within the limits set by KEBS and WHO. However, the concentration of nitrate in several boreholes during the dry season was within the range that cause chronic health effects. Groundwater from most boreholes in Chuka Sub-County is generally safe for domestic uses but require regular monitoring for quality.Item Food Rheology using Dynamic Mechanical Analysis; A short review(Paul Kamweru, 2020-02) Kamweru Kuria, PaulAn ideal elastic material will deform finitely and recover its original shape and size upon the removal of the applied deforming load. On the other hand an ideal fluid will deform and continue to deform as long as the deforming load is applied, and finally the material doesn’t recover from that deformation even when the load is removed. These two responses are termed as ‘elastic’ and ‘viscous’ respectively. Most materials, exhibits an intermediate viscous and elastic behavior and are referred to as “viscoelastic”. A good example of such materials are polymers. In addition almost all foods, both liquid and solid, belong to this group. The viscoelasticity of materials can be determined by transient or dynamic methods. The transient methods are two pronged; stress relaxation which is the application of constant and instantaneous strain and measuring decaying stress with respect to time and creep which is the application of constant and instantaneous stress and measuring increasing strain with time. The transient methods are easy to perform, however, they are limited in the sense that the material response cannot be determined as a function of frequency. The dynamic methods are performed applying a small sinusoidal strain (or stress) and measuring the resulting stress (or strain). Due to the enormous list of advantages of performing dynamic tests, the method has been very popular in polymer studies for many years. This brief review demonstrates that the method has found a now increasing usage, especially in the last two decades, in studies of food, what has been referred to as Food Rheology.Item Crystal structure of η 6 -p-cymene-iodido-(N-isopropyl-1-(pyridin-2-yl) methanimine-κ 2N,N′)ruthenium(II) hexafluorophosphate(V), C19H26IN2F6Ru(De Gruyter, 2019-12-07) Gichumbi, Joel M.; Omondi, Bernard; Friedrich, Holger B.C19H26IN2F6Ru, triclinic, P¯1 (no. 2), a = 9.240(2) Å, b = 10.019(3) Å, c = 12.689(3) Å, α = 78.921°, β = 81.596(10)°, γ = 83.654°, V = 1136.30(5) Å3 , Z = 2, Rgt(F) = 0.0174, wRref(F 2 ) = 0.0440, T = 173 K.Item Spinel ferrites gas sensors: a review of sensing parameters, mechanism and the effects of ion substitution(Taylor & Francis Group, LLC, 2021-09-03) Njoroge, Muasya Alex; Kirimi, Nixon Mutwiri; Kuria, Kamweru PaulThere is an increasing demand of highly sensitive, stable and highly selective gas sensors to detect toxic gases. This is inspired by the need to monitor the concentration of these gases in order to guarantee humans, animals and environmental safety. Metal ferrites (AFe2O3, where A is a metal) based sensors are paramount in this field of sensing. Among the gases detectable using metal ferrites includes carbon monoxide (CO), liquefied petroleum gas (LPG), hydrogen sulfide (H2S), petrol and methane (CH4). This reviews presents various parameters which plays key role in the design of ferrite gas sensors. They include; operating temperatures, dopants, grain size, particle size, selectivity, surface area, concentration of the gas, sensitivity as well as recovery time. In addition, the various methods which are used to synthesize ferrite gas sensors are briefly explained. Key considerations in the designing of excellent ferrite gas sensors such as calcination temperature, working temperature, dopants, and concentration as well as optimization condition among others are outlined. In addition this paper reviews the various metal ferrites such as nickel ferrites and nickel doped ferrites, cobalt and cobalt doped ferrites, zinc and zinc doped ferrites, magnesium and magnesium doped ferrites among others that have been researched as gas sensors.Item EFFECT OF COOKING METHODS AND DURATION ON ASCORBIC ACID CONCENTRATION OF SELECTED VEGETABLES(RJLBPCS, 2020-12-01) Wambua, Angeline; Kariuki, Richard; Gachoki, Peter; Okello, Vincent; Opiata, PatrickCooking vegetables before they are consumed helps in making them more palatable in addition to improving taste and texture. On the other hand, cooking causes a substantial change in the composition of chemicals thus affecting concentration and availability of nutrients. There are some cooking methods that cause oxidization of the antioxidants therefore affecting the retention of nutrients of the vegetables. Therefore, it is vital to opt for a cooking method which will lead to optimal retention of nutrients. This study was designed to determine the reduction in Vitamin C concentration associated with different cooking methods of green leafy vegetables. Vitamin C content of green leafy vegetables namely, African nightshade (Solanum nigrum) and amaranth (Amaranthus viridis) were selected for the study. Vitamin C content of the above sample vegetables were estimated using spectrophotometric method at a wavelength of 245nm. Processing methods which were employed were boiling and microwave heating which were performed at a timely interval. The findings showed that microwaving had the highest vitamin C loss. The results also showed that long duration of cooking led to massive loss from the selected vegetables. It was concluded that the water used for cooking vegetables should not be discarded for maximum retention of vitamin C in vegetables. Based on the study, it is recommended that the best duration for cooking Solanum nigrum and Amaranthus viridis should be less than 10 minutes (dependent on consumer preference) so as to retain maximum ascorbic acid.Item Effect of the Y element on the structural, electronic and magnetic properties of Heusler compounds Co2YIn (Y = V, Nb, and Ti): An ab initio study(AIP Advances, 2021-01-06) Muthui, Zipporah; Musembi, Robinson; Mwabora, Julius; Kashyap, ArtiWe report the effect of varying the Y element on the structural, electronic and magnetic properties of Co2YIn (Y = V, Nb, Ti) Heusler compounds using Density Functional Theory (DFT). The effect of the lattice parameter and total number of valence electrons on spin polarization and the magnetic properties of these Heusler compounds is compared. Co2VIn and Co2NbIn have the same number of valence electrons as Nb and V are from the same group in the periodic table. Co2VIn has almost the same lattice constant as Co2TiIn but they differ in the total number of valence electrons by one, as Ti and V are next neighbors in the same period of the periodic table. The optimized lattice parameters for Co2NbIn and Co2TiIn are found to be 6.20 Å and 6.05 Å respectively, while that of Co2VIn has been reported to be 6.00 Å. Co2NbIn is half metallic with an energy band gap of 0.1 eV in the minority states and has total magnetic moments of 2.02 μB/f.u. very close to the 2.00 μB/f.u. predicted by the Slater-Pauling rule, while Co2TiIn is not half metallic but has a highly spin polarized electronic structure having a spin polarization of 89.59% and total magnetic moments of 1.04μB/f.u. While reducing the number of the valence electrons by one in Co2TiIn has a significant effect on the magnetic moments and spin polarization, an increase in the lattice parameter while maintaining the same number of valence electrons in Co2NbIn does not result in the destruction of the half metallic gap.Item Characterization of rice husk ash prepared by open air burning and furnace calcination(Academic Journals, 2020) Kaleli, Mbinda Jonathan; Kamweru, Paul Kuria; Gichumbi, Joel Mwangi; Ndiritu, Francis GichukiRice husk (RH) is an agricultural waste, and easily available in rice growing areas. The husk is mostly burnt as a way of getting rid of it. The ash obtained after burning or calcination may have economic application, mainly dependent on its properties. These properties in turn depend on the calcination method. However, for commercial viability, and for many applications, the calcination method should not only be as simple as possible but also cheap. This study characterized the elemental composition, crystallinity, functional bonds present and morphology of rice husk ash (RHA) obtained in two ways, that is, calcination of rice husks in a muffle furnace (FRHA) at a temperature of 700°C and open air burning (ORHA) at uncontrolled temperatures. The elemental composition done by Atomic Absorption Spectroscopy showed a high percentage of silicon that is 81.01 and 79.12% for ORHA and FRHA, respectively. X-ray fluorescence showed a high percentage of silica (SiO2), 95.45 and 94.85% for ORHA and FRHA, respectively. X-ray diffractograms indicate that the FRHA was crystalline with the highest peak at 21.8°; while ORHA was amorphous in nature. Fourier Transform Infra-Red spectra confirmed the presence of –OH groups and O-Si-O bonds in the two types of ash. Scanning electron microscopy analysis showed agglomerated ORHA, which may be due to the presence of hydrogen bonding between silanol groups on the surface of rice husk ash for FRHA, and presence of –OH groups in ORHA. The study shows that ORHA is as good as FRHA in applications where crystallinity is optional.Item Generating, Rectifying and Stepping Up the Voltage Output of Piezoelectric Plate(International Journal of Research Publications, 2020) Mwanzia, Bonface; Kamweru, Paul KuriaEnergy is required in all sectors that either supports or improves human life. However, some of the methods of power generation e.g. the fossils fuels are non-renewable and have byproducts that harms the environment. For example, they cause pollution that leads to greenhouse effect which will result in global warming hence causing climate change. There is a need for generation of electricity by methods where renewable/green energy sources can be used for generating electric power. Piezoelectric power is one such method where mechanical energy is converted into electrical energy. A lot of mechanical energy is wasted when people move on the streets, pavements, gymnastic rooms and also by the movement of vehicles on the road. present work aimed at harvesting mechanical energy (for example from human footsteps, vehicle movements on roads and public gathering situations for clean and pollution free power generation. the general objective was to generate, rectify and step up the voltage output of the piezo electric plate. This study designed a portable kit comprising of the piezoelectric transducers either in parallel or series combination, together with a voltage step up and rectifier. The study experimented energy generation with the kit results using weights ranging from 10g-1000g. The results shows that the output voltage was directly proportional to the weights. The kit stepped up and the output of 1.5 v to 3 v. From the analysis the series combination of the PZT gives the highest output and thus for any designer who needs to generate power using PZT should consider the series configuration connected to the voltage doubler circuit.Item Characterization of rice husk ash prepared by open air burning and furnace calcination(Academic Journals, 2020) Kaleli, Mbinda Jonathan; Kamweru, Paul Kuria; Ndiritu, Francis GichukiRice husk (RH) is an agricultural waste, and easily available in rice growing areas. The husk is mostly burnt as a way of getting rid of it. The ash obtained after burning or calcination may have economic application, mainly dependent on its properties. These properties in turn depend on the calcination method. However, for commercial viability, and for many applications, the calcination method should not only be as simple as possible but also cheap. This study characterized the elemental composition, crystallinity, functional bonds present and morphology of rice husk ash (RHA) obtained in two ways, that is, calcination of rice husks in a muffle furnace (FRHA) at a temperature of 700°C and open air burning (ORHA) at uncontrolled temperatures. The elemental composition done by Atomic Absorption Spectroscopy showed a high percentage of silicon that is 81.01 and 79.12% for ORHA and FRHA, respectively. X-ray fluorescence showed a high percentage of silica (SiO2), 95.45 and 94.85% for ORHA and FRHA, respectively. X-ray diffractograms indicate that the FRHA was crystalline with the highest peak at 21.8°; while ORHA was amorphous in nature. Fourier Transform Infra-Red spectra confirmed the presence of –OH groups and O-Si-O bonds in the two types of ash. Scanning electron microscopy analysis showed agglomerated ORHA, which may be due to the presence of hydrogen bonding between silanol groups on the surface of rice husk ash for FRHA, and presence of –OH groups in ORHA. The study shows that ORHA is as good as FRHA in applications where crystallinity is optional.Item Optical and scanning kelvin probe microscopic characterization of sol-gel synthesized aluminum doped zinc cobalt ferrite nanoparticles(academic Journals, 2020) Sabastine, Butembu; Akou, Osamong Gideon; Kuria, Kamweru Paul; Mwangi, Gichumbi Joel; Ndiritu, FrancisIn this work, Zn1-xCoFe2AlxO4 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) ferrites were synthesized using the sol-gel method. XRD analysis was done and confirmed the formation of spinel structure, where the particle size and lattice parameter decrease with increase of aluminum concentration. This may be attributed to a shift of the bigger Al3+ ions, from the tetrahedral to the octahedral sites, interchanging with smaller Zn2+ ions and that consequently result to a decreased unit cell size. The Scanning Kelvin Probe Microscopy (SKPM) showed that the work function average ranges between 200 and 680 mV for the different concentration of aluminum in the samples. Fractural analysis indicated a small fracture between the samples of different ratios which can be attributed to the method used to prepare as well as the shifting of the Al3+ ions. The UV-vis spectroscopy showed variation of energy gap with increasing aluminum concentration, and an increased optical absorbance as the Al3+ ions were introduced in the samples.Item Surface potential, fermi level and band gap energy of copper doped magnesium nickel ferrite nanoparticles(Sami Publishing Compan, 2020) Osamong, Gideon; Kamweru, Paul Kuria; Gichumbi, Joel Mwangi; Ndiritu, Francis GichukiOptical, electrical, and electronic properties of materials are essential in the fabrication of electronic devices. These properties can be improved through doping and reduction of the size of a material to nanoscale. In this study, copper doped magnesium-nickel (CuxMg1-xNiFe2O4, for x=0.00, 0.15, 0.30, 0.45, 0.60, 0.75, 1.00) ferrite nanoparticles were synthesized using the citragel auto combustion method. The electronic and optical properties were evaluated using the scanning Kelvin probe microscopy (SKPM) and UVvisible, respectively. The UV-visible studies revealed that, the band gap energy was at the range of 3.600-3.750 eV. The band gap was noted to increase with copper content up to x=0.45 which then started to decrease. The undoped sample displayed the lowest band gap energy in comparison with the doped. SKPM analysis exhibited the surface potential in the range 4.361-5.002 eV for the area scan and 4.251-5.006 eV for the line scans for the samples. The sample with x=0.75 showed a positive work function for both area and line scans, and all the others had a negative work function. The doped ferrite exhibited the properties that could be applied in optical devices, storage devices, and recording devices. © 2021 by SPC (Sami Publishing Company), Asian Journal of Nanoscience and Materials, Reproduction is permitted for noncommercial purposesItem Chlorido-(η 6 -p-cymene)-(bis(pyrazol-1-yl)methaneκ 2N,N0 )Osmium(II) Tetrafluoroborate, C17H22BClF4N4Os(MDPI, 2022) Mambanda, Allen; Kanyora, Amos K.; Ongoma, Peter; Gichumbi, Joel; Omondi, Reinner O.The powder of the arene osmium(II) complex, [Os(II)(dpzm)(η 6 -p-cym)Cl]BF4 (dpzm = di(1H-pyrazol-1-yl)methane; η 6 -p-cym = para-cymene), with a formula of C17H22BClF4N4Os (referred to herein as 1) was isolated from the reaction of [(η 6 -p-cym)Os(µ-Cl)(Cl)]2 with dpzm dissolved in acetonitrile and under a flow of nitrogen gas. It was characterized by spectroscopic techniques (viz., FTIR, 1H NMR, UV-Visible absorption). Yellow crystal blocks of 1 were grown by the slow evaporation from the methanolic solution of its powder. The single-crystal X-ray structure of 1 was solved by diffraction analysis on a Bruker APEX Duo CCD area detector diffractometer using the Cu(Kα), λ = 1.54178 Å as the radiation source, and 1 crystallizes in the monoclinic crystal system and the C2/c (no. 15) space group.Item Crystal structure of chlorido-(η6 - toluene)(2,2′-bipyridine-κ2 N,N′)ruthenium(II) hexafluorophosphate, C17H16ClN2RuPF6(De Gruyter, 2022) Gichumbi, Joel M.; Zamisa, Sizwe J.; Friedrich, Holger B.C17H16ClN2RuPF6, monoclinic, P21/c (no. 14), a = 14.4426(9) Å, b = 8.3311(5) Å, c = 16.413(1) Å, β = 109.2690°, V = 1864.2(2) Å3 , Z = 4, Rgt(F) = 0.0309, wRref(F2 ) = 0.0697, T = 173 K.Item Determination of precursors of acrylamide formation in roasted maize(Advances in Phytochemistry, Textile and Renewable Energy Research for Industrial Growth – Nzila et al. (Eds), 2022-04) Koske, M.C.; Kiprop, A.; Ongoma, O.; Kariuki, P.; Kagwanja, S.M.; Gichumbi, J.M.Acrylamide, an organic compound with the formula CH2=CHCONH2, is a contaminant generated through high-temperature cooking processes as a result of Maillard reactions catalyzed by the presence of reducing sugars and free amino acids in starchy food compounds. Acrylamide and its major metabolite, glycidamide, have been considered probable human carcinogens. In this study, we report on the acrylamide content in roasted maize from some Kenyan markets. Raw maize was purchased from local markets and roasted under laboratory conditions. They were crushed and extracted using water and hexane in a ratio of 2:1. The extract was derivatized with potassium bromate and potassium bromide and further subjected to liquid–liquid extraction using ethyl acetate-hexane (4:1, v/v). The final bromoprop-2-enamide (BPA) analyte was analyzed using gas chromatography–flame ionization detector. Acrylamide was not detected in any of the samples (at limit of detection of 20 µg/kg), which was consistent with reports from other countries.Item Assessment of Selected Physico-Chemical Parameters of Groundwater in Chuka Igambang’ombe Constituency, Kenya(Chuka University, 2022) Maweu, Bonface K.; Chabari, Kithaka Samson; Nguku, James Kyalo; Chuka, UniversityGroundwater is an essential source of water for drinking and other domestic uses. Recently, there has been high dependence on groundwater due to water shortage as a result of changing climates, and higher costs of accessing piped water. An occurrence of the physico-chemical parameters of the groundwater in levels past the WHO highest permissible limits can cause serious health implications to the consumers of the groundwater. This study therefore, assessed the extent of the physico-chemical parameters concentration of the groundwater in Chuka, Igambang’ombe constituency. A total of five samples was collected from 5 boreholes in the Mucw’a and Ndagani regions surrounding the Chuka University main campus. Selected physical parameters were recorded onsite by use of portable apparatus. Samples for testing chemical parameters were collected and transported in cooler boxes to Chuka University laboratories for analysis. Physical parameters determined onsite were dissolved oxygen (DO), temperature, and the pH. Dissolved Oxygen meter, mercury thermometer, and pH meter were the equipment used to test the respective physical parameters. UV- spectrophotometry was used to analyze the chemical parameters: nitrates, and phosphates, where absorbance was recorded at a wavelength of 220-820 nm and 880nm respectively. The assessment was conducted during the relatively dry months of January to March. The temperature of the water ranged from 22.8-25.20C. The pH levels ranged from 4.50 – 9.50. The high altitude nitrate levels were 2.4mg/L, and 7.37mg/L at the low altitude. The phosphate concentrations were below detectable limits. The results were then compared with WHO standards for the highest permissible levels for the tested parameters to determine the suitability of the water for consumption. All the tested parameters lied within the WHO permissible limits for drinking water except for the pH levels.Item Structural properties of high density polyethylene matrix composites reinforced with open air and furnace rice husks ash(Journal of Chemical Engineering and Materials Science, 2021-12) Jonathan, M.K.; Osamong, G.A.; Butembu, S.; Kamweru, P.K.; Gichumbi, J.M.; Ndiritu, F.G.In this work, rice husks ash (RHA) was introduced to pure and recycled high density polyethylene (HDPE) matrix, at varying ration (0-50%) to formulate rice husks ash High density polyethylene (RHAHDPE) composite. RHA was obtained by burning fresh rice husks either by open-air burning (oRHA) or furnace calcination at 700°C (fRHA). The composite samples were made by melt-mixing the HDPE in an oven at a temperature of 150°C and adding different percentages of RHA in presence of maleic anhydride compatibilizer. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were carried out to determine the structural properties of the samples, and both suggest occurrence of composting chemical changes. For all RHA-HDPE samples, a broad band was noted between 970-070cm-1 . This was highly contributed by the RHA and associated to Si-O-Si stretching modes. Other peaks are associated with Si-O-C interaction and O-Si-O bending vibrations in the samples. Scanning electron Microscopy (SEM) micrographs for HDPE indicated a smooth and uniform surface with a number of voids. On addition of RHA, the particles filled these voids making the sample surface rough. This roughness is seen to increase with increased percentage of RHA. The studies conclude that the cheaply obtained oRHA is as good as the fRHA in making RHA-HDPE composite.Item Spinel ferrites gas sensors: a review of sensing parameters, mechanism and the effects of ion substitution(Taylor & Francis, 2021-09) Njoroge, Muasya Alex; Kirimi, Nixon Mutwiri; Kuria, Kamweru PaulThere is an increasing demand of highly sensitive, stable and highly selective gas sensors to detect toxic gases. This is inspired by the need to monitor the concentration of these gases in order to guarantee humans, animals and environmental safety. Metal ferrites (AFe2O3, where A is a metal) based sensors are paramount in this field of sensing. Among the gases detectable using metal ferrites includes carbon monoxide (CO), liquefied petroleum gas (LPG), hydrogen sulfide (H2S), petrol and methane (CH4). This reviews presents various parameters which plays key role in the design of ferrite gas sensors. They include; operating temperatures, dopants, grain size, particle size, selectivity, surface area, concentration of the gas, sensitivity as well as recovery time. In addition, the various methods which are used to synthesize ferrite gas sensors are briefly explained. Key considerations in the designing of excellent ferrite gas sensors such as calcination temperature, working temperature, dopants, and concentration as well as optimization condition among others are outlined. In addition this paper reviews the various metal ferrites such as nickel ferrites and nickel doped ferrites, cobalt and cobalt doped ferrites, zinc and zinc doped ferrites, magnesium and magnesium doped ferrites among others that have been researched as gas sensors.Item COMPLEXOMETRIC DETERMINATION OF ZINC USING HYDROXYTRIAZENE AS A METALLOCHROMIC INDICATOR(2020) Ombaka, OchiengNew metallochromic indicators belonging to the class of hydroxytriazenes has been evaluated for the direct complexometric determination of Zinc in the presence of diverse ions. Reagent no (i), (ii) and (iii) has been found to be excellent indicators in the titration with EDTA at pH 6.95-7.50, 6.90-7.60 and 7.00-7.50 respectively. The colour at the end point was from light green to colourless and the titration was carried out between temperature range of 20-600C. Cl- , Br- ,CH3COO- , CO3 2- , SO4 2- , NO2 - , SO3 2- , F- , NO3 - , I- , S 2- , WO4 2- , MO7O24 6- , NH4 + , Na+ , K+ , U(VI), Mn(II), Ba(II), Hg(II), Sn(II), Cd(II), Mg(II), Ca (II), Zr(IV) can be tolerated in the titration of zinc (II) when they are present in equivalent amount with that of zinc (II). However, PO4 3- , Co (II), Cu (II) and Ni (II) interferes and when present in the environmental samples, separation techniques such as masking and demasking agents must be employed. The utility of the technique was checked by using 3-Hydroxy-3-m-toly-1-0-Carboxyphenyltriazene for estimation of zinc in zinc-copper alloy and the results had a maximum relative error of +1.53 and standard deviation of ±0.0378 using Sodium thiosulphate to mask copper ions, hence the study clearly indicated that reagent no (i) and (ii) which have high sensitivity, high selectivity and fairly a wide pH range can be used as metallochromic indicators for estimation of zinc in environmental sample where zinc is the major element.Item Application of arene ruthenium(II) complexes with pyridine-2-carboxaldimine ligands in the transfer hydrogenation of ketones(Elsevier, 2016-05) Gichumbi, Joel M.; Friedrich, Holger B.; Omondi, BernardThe reaction of various pyridine-2-carboxaldimine ligands with the [(η6-arene)Ru(μ-Cl)Cl]2 dimer followed by a metathesis reaction with ammonium hexaflourophosphate, yielded the ruthenium(II) arene complex salts [(η6-arene)RuCl(C5H4N-2 CH N-Ar]PF6; where (arene = C6H6 (1), p-cymene (2), Ar = 3, 5-dimethyl phenyl (a), 2,3-dimethyl phenyl (b), 2,5-dimethyl phenyl (c), 3,4-dimethyl phenyl (d)). The compounds were characterized by elemental analysis, FT- IR, UV–vis and 1H and 13C NMR. Single crystal X-ray structures for compounds 1a, 1d and 2e were also determined and showed that the ruthenium(II) centre has a pseudo-octahedral geometry and the molecule adopted a three legged piano stool geometry in which the arene ring occupies the apex and the nitrogen atoms of the N,N′-bidentate ligand and the chloride atom the base of the stool. The Ru(II) complex salts were active for the catalytic transfer hydrogenation of ketones into alcohols in the presence of NaOH using 2-propanol as the hydrogen source at 82 °C. The complexes were suitable for a wide range of aliphatic, cyclic and aromatic ketones giving good turn over numbers.