COORDINATIVE INTERACTION OF CHITOSAN-AZO DYES TOWARDS SELECTED FIRST ROW TRANSITION METALS

Chitosan is an abundant bio-polymer obtained by alkaline deacetylation of chitin in the exoskeleton of crustaceans. Chitosan was found to be an attractive alternative to other bio materials due to its significant physicochemical behavior and ability to selectively bind to transition and post transition metals. In order to improve the performance of this bio-polymer, chemical modification of chitosan composite and its derivatives have gained much attention. In this study, a new biopolymeric ligand was synthesized by functionalizing chitosan with eriochrome black T (EBT) and sudan III (S3) dyes. The functionalized compounds were interacted with Co(II), Ni(II), Cu(II) and Zn(II) metal ions at varied concentrations leading to complex formation. Both the new ligand and the complexes obtained at high yields were characterized using Fourier Transform Infrared (FT-IR) and Uv-Vis Spectroscopy. The FT-IR spectra revealed a possible hydrogen bonding between chitosan and the azo dye. It also suggests an interaction between the N=N of the ligand with the metal ions. In addition, the Uv-Visible spectra studies showed that on reacting various concentrations of metal ions with ligand the absorbance increases with decreasing concentration of the metal ions and was able to interact with as low as 0.001 M of the studied metal salts. &nbsp

The Use of Coconut-Shell Based Activated Carbon as an Adsorbent in the Treatment of Hard Water

One of the undesirable characteristics of some groundwater sources is hardness, which has adverse effects on water pipes, boilers and soap consumption. Therefore, several treatment processes have been introduced to remove or reduce the hardness from water. One of the innovations in this regard is coconut-shell which is readily available and could be used to produce resource materials such as activated carbon that is of public health importance. The initial values of Calcium, Magnesium and Total Hardness in the raw water sample were 120.24mg/L, 98.29mg/L and 588.00mg/L, respectively which are above the World Health Organization (WHO) standard. The highest quantities of Calcium, Magnesium and Total Hardness were removed at a contact time of 60 minutes with removal efficiencies of 80%, 60.44% and 66.71%, respectively. Also, the optimum dosage occurred at 1.2g for Calcium hardness, 1.5g for Magnesium hardness and Total hardness. In conclusion, the adsorbent obtained from the coconut-shell has the potential of removing Calcium, Magnesium and Total Hardness in water

Adsorption kinetics of cadmium and lead by chitosan

An evaluation of the kinetics and capacity of chitosan to trap lead and cadmium ions in aqueous solution was carried out at 25oC using concentration and contact time as parameters. The experimentswere done as batch process. Our results show that the adsorption process is concentration-driven with high capacity of chitosan for the adsorption of these metal ions. The Infra red spectroscopic study on the chitosan and the metal-chitosan complexes reveal a metal coordination based on the observed characteristic band changes. At initial lead concentrations of 1000, 500, 400, 250 and 100 mg/L, the adsorbed lead ion concentrations are 557, 265, 218, 132 and 65 mg/L, respectively. However, for the cadmium, the adsorbed concentrations are 263, 165, 152, 78 and 45 mg/L, respectively at the same initial concentrations. The lead and cadmium adsorption kinetic behavior could not be described using the Langmuir isotherm over the whole concentration range but Freundlich isotherm conforms to the experimental data

AN IMPROVED SYNTHESIS OF ETHYL 6-(BENZIMIDAZOL-2-YL) PYRIDINE-2-CARBOXYLATE AND APPLICATION OF ITS NICKEL COMPLEX TOWARDS ETHYLENE CATALYTIC BEHAVIOR

Ethyl 6-(benzimidazol-2-yl)-pyridine-2-carboxylate (EBIPC) was efficiently synthesized by condensation reaction of β-keto ester pyridine carboxylate and o-phenylenediamine. The compound was characterized by elemental analysis and spectroscopic techniques (IR and NMR) to confirm its molecular structure. This new protocol afforded a product with higher yield (65.1%) and reduced number of reaction steps. Upon activation with trimethylaluminum (Me3Al) as the co-catalyst, the nickel complexes exhibited high catalytic activities for ethylene oligomerization (up to 1.26 x 106 g mol-1(Ni) h-1). Various polymerization reaction conditions significantly influenced the catalytic properties of the complexes.     &nbsp

Performance Analysis of Improved Technique for Optimal Frequency Spectrum Utilization Considering Energy and Eigenvalue Detectors

Recently, exponential rise in the demand of wireless communication has led to gross reduction in the availability of wireless frequency spectrum to meet the proliferation of demands. Overlay and underlay cognitive radio used to address this problem is characterized with poor management of the assigned spectrum. The basic and essential mechanism of cognitive Radio (CR) to find unused spectrum is called Spectrum Sensing. This is important in optimizing frequency allocation for the increasing wireless communication system. Hence, this paper developed an energy efficient spectrum sensing technique for detection of white and brown space using energy and eigenvalue detector. Based on a predefined switching algorithm, the developed spectrum sensing system switches between overlay and underlay approach when there is presence of white space and brown space respectively. During the underlay approach, the cognitive user (CU) signal is coded using a Code Division Multiple Access (CDMA) to prevent primary users (PU) receiver from hearing CU signal and thereby improve the security of CU. Also, Hybrid Decode Amplify and Forward (H-DAF) cooperative relay technique is incorporated to enhance the coverage area of the cognitive user. However, during the overlay approach, H-DAF cooperative relay technique will be in sleep mode since CU can transmit with the maximum transmitting power. During the underlay approach, the received signal at the relay node is decoded, amplified, and coded using CDMA before forwarding to the CU receiver. The paper compared the performance of the two detectors by simulating the developed algorithm using MATLAB R2021a. Evaluation was based on Throughput, Spectrum Utilization Efficiency, and Spectral Efficiency by comparing Energy detector and Eigen Value detector. Keywords: Energy Detector (ED), Eigenvalue Detector (EVD), White Space, Brown Space, Spectrum Sensing (SS), Code Division Multiple Access (CDMA). DOI: 10.7176/ISDE/13-2-04 Publication date:July 31st 202

Food Expenditure Patterns Among Urban Households In Ibadan Southwest Local Government Area, Oyo State

This study examines food expenditure patterns among urban households in Ibadan South West Local Government Area of Oyo State. The primary data used for the study were obtained through structured questionnaire using random sampling technique. Descriptive statistics and least square regression model were used to analyse the data collected from respondents. Descriptive analysis showed that 82.5% of the household heads were males, 65% of them were married, and 55% fell within the age bracket of 30 and 39 years, while 65% were salary-earners. Most of the respondents (79.2%) had tertiary education and the average household size was found to be 5. Furthermore, 49.2% bought foodstuffs from the market for home consumption on a monthly basis and 52.5% spent less than N10, 000 monthly on food.  The result of the least square regression model showed that the age of respondents, level of education and occupation (salary-earner or self-employed) of the household head, as well as the household income were significantly influenced by household’s monthly food expenditure in the study area. The study recommends among other things enlightenment programmes that will    educate the urban dwellers on the  need to eat good quality and hygienic food.   &nbsp

A comparative study of some robust ridge and liu estimators

In multiple linear regression analysis, multicollinearity and outliers are two main problems. When multicollinearity exists, biased estimation techniques such as Ridge and Liu Estimators are preferable to Ordinary Least Square. On the other hand, when outliers exist in the data, robust estimators like M, MM, LTS and S Estimators, are preferred. To handle these two problems jointly, the study combines the Ridge and Liu Estimators with Robust Estimators to provide Robust Ridge and Robust Liu estimators respectively. The Mean Square Error (MSE) criterion was used to compare the performance of the estimators. Application to the proposed estimators to three (3) real life data set with multicollinearity and outliers problems reveals that the M-Liu and LTS-Liu Estimator are generally most efficient..Keywords: Ordinary Least Squares, Ridge Regression Estimator, Liu Estimator, Robust Estimator, Robust Ridge Regression Estimator, Robust Liu Estimato

Pre-concentration of Toxic Metals using Electrospun Amino-functionalized Nylon-6 Nanofibre Sorbent

This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58 m2 g–1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimal pH for the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isothermand followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3 + H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption(0.34) > HNO3 + H2O2 (0.23) digestion. A similar trend was observed for Ni in river water as well as Ni and Cd in tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods (pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbent presents an efficient and cost-effective alternative for pre-concentration of toxic metals in aqueous environments.Keywords: Electrospinning, pre-concentration, heavy metals, nylon-