Comparative Study of Rates of Biosorption for Selected Single and Mixed Metal Ions using Natural Products

Heavy metals are usually found in low concentrations in natural aquatic ecosystem. In recent times, however, the occurrence of metal contaminants especially heavy metals in excess of natural loads has become a problem of increasing concern. The contributing factors are rapid growth of population, increased urbanization and expansion of industrial activities, exploration and exploitation of natural resources, extension of irrigation and other modern agricultural practices as well as lack of environmental regulations. This therefore, calls for efficient, cheap, available and non polluting method of controlling presence of heavy metals in water bodies. Use of natural biosorbents such as algae has demonstrated great potential to remove heavy metals from wastewater. An investigation of the effect of contact time, reaction kinetics, influence of ionic sizes and influence of presence of other metal ions in biosorption of heavy metals Cu, Zn and Pb using Ascophyllum nodosum has been done. Model wastewater solution containing a known concentration of the given heavy metal ions was prepared for both single and mixed at a fixed pH of 5. A 0.25g mass of dry algae was introduced for every 100 mL solution. Change in level of concentration was monitored at intervals of 10 minutes using AAS until the rate of biosorption was almost constant.  The sorption process occurred in two stages; first being rapid adsorption and then gradual adsorption that was almost constant. Pb was most biosorbed while Zn was least for both systems, adopting the order Pb > Cu > Zn. The data obtained fitted both Langmuir isotherm and experimental parameters were determined. The order of reaction was found to follow pseudo second order after comparison of R2 values that were deduced from first and second order linearized plots.Key words: Biosorption, heavy metals, algae, wastewater, pollutio

Partial Density of States Ligand Field Theory (PDOS-LFT): Recovering a LFT-Like Picture and Application to Photoproperties of Ruthenium(II) Polypyridine Complexes

Gas phase density-functional theory (DFT) and time-dependent DFT (TD-DFT) calculations are reported for a data base of 98 ruthenium(II) polypyridine complexes. Comparison with X-ray crystal geometries and with experimental absorption spectra measured in solution show an excellent linear correlation with the results of the gas phase calculations. Comparing this with the usual chemical understanding based upon ligand field theory (LFT) is complicated by the large number of molecular orbitals present and especially by the heavy mixing of the antibonding metal e*$_{g}$ orbitals with ligand orbitals. Nevertheless, we show that a deeper understanding can be obtained by a partial density-of-states (PDOS) analysis which allows us to extract approximate metal t$_{2g}$ and e*$_{g}$ and ligand \pi* orbital energies in a well-defined way, thus providing a PDOS analogue of LFT (PDOS-LFT). Not only do PDOS-LFT energies generate a spectrochemical series for the ligands, but orbital energy differences provide good estimates of TD-DFT absorption energies. Encouraged by this success, we use frontier-molecular-orbital-theory-like reasoning to construct a model which allows us in most, but not all, of the cases studied to use PDOS-LFT energies to provide a semiquantitative relationship between luminescence lifetimes at room temperature and liquid nitrogen temperature

Quantification of Heavy Metals in Breast Milk Samples Sampled from Kilimani/Kidoti in Zanzibar

People of Zanzibar are perpetual users of tomatoes.  Different varieties of tomatoes are regularly consumed in day-to-day meals in Zanzibar. These fruits are farmed under different settings varying from purely organic mode to extensive use of agrochemicals. It is well known that the use of agrochemicals may give rise to heavy metals contaminations with significant health impacts to consumers. The use of fertilizers and pesticides in some areas during cultivation may bring about individuals to eat tomatoes together with harmful heavy metals. However, no study has been done to find the quantity of heavy metals entered in consumers’ bodies. The objective of this study was to quantify heavy metals present in breast milk of individual tomato consumers. The methodology used was sampling, processing, digestion and analysis. The instrument used for analysis was Atomic Absorption Spectrometer (AAS). Samples were collected, digested with HNO3 and H2O2 in a semi–closed glass digestion apparatus. After cooling, volume was adjusted to 25 ml with distilled water and analyzed by AAS. Zinc detected by AA spectrometer ranged from 231 μg/l to 1466 μg/l of milk, with average of 900±457 μg/l. Cadmium ranged from 24.1 μg/l to 35.9 μg/l with average of 31.1±3.46 μg/l. Lead ranged from 32.4 to 1630 μg/l with average of 707±582 μg/l. The concentration of Al metal, which was detected in only one sample, was 0.91 μg/l. The results show that breast milk contains heavy metals contaminants necessary to be removed before infant feeding

An Assessment of the Challenges facing the Implementation of SMASSE Project Activities in Bomet District, Kenya

The Poor performance of students in science subjects (physics, chemistry and biology) in Kenyan secondary schools has been a persistent problem. In an attempt to stop this, the government implemented the SMASSE program in conjunction with JAICA from the government of Japan. The implementation of this program has encountered copious challenges over the years which are threatening its success. Thus, this study aimed to investigate the challenges facing the implementation of SMASSE Project Activities. The study was conducted in Bomet County in Kenya. The target population comprised of all the 121 secondary school head teachers and science teachers in the study area. Out of these, a sample size of 50 respondents was randomly selected from principals and teachers of public secondary schools in the district. The schools were stratified into boys’, girls’ and mixed secondary schools to ensure uniformity. Data was collected from the respondents using structured questionnaires. Data was analyzed descriptively using SPSS. Results were presented in form of frequencies and percentages. The results indicate that 65% of the teachers sampled were not adequately prepared for the program. In addition, 75% of the teachers stated that the boarding facilities during SMASSE were inadequate and of low standards. 70% were of the opinion that catering services offered to them during the training were of low quality. The findings further revealed that 75% of the teachers lacked sufficient time to apply ASEI-PDSI concept in lessons, while 90% stated that heavy teaching load was a challenge. 100% considered low morale among teachers a challenge. 75% of the head teachers agreed that conflict of interest was a major challenge, that is, science and mathematics teachers attend INSET during the holidays while their art-based counterparts were free to attend their personal interests. 90% agreed that another challenge during the implementation of SMASSE was non- collection/non- remittance of SMASSE funds to District Planning Committee (DPC). Finally 75% of the head teachers agreed that high staff turnover and the transfer of trainers to non-curriculum implementing posts challenged the implementation process. The study concluded from the findings that SMASSE project implementation is facing major challenges. The ministry of Education should employ more mathematics and science teachers to address the widespread teachers‟ shortage and in the process deal with some of these challenges. In addition, the negative attitude towards the project can be changed through payment of allowances for those attending the INSET, provide decent boarding and catering facilities during the training. Finally, the principles of SMASSE INSET should be incorporated into the training curriculum of secondary teacher training institutions. This would save on costs and time

Quantification of Lycopene from Tomatoes and Watermelons by Using Beer-Lambert Principle

Red tomatoes and red-fleshed watermelons contain a high level of lycopene.  It is well known that lycopene is precursor to vitamin A. In Uganda, and East Africa in general, there are so many tomato and watermelon varieties with little information on their lycopene content. However, no study has been done to estimate the quantity of lycopene in fresh tomatoes and watermelons in Uganda. The objective of this study was to quantify lycopene by using Beer-Lambert Principle. The varieties were bought from Nakulabye market in Kampala, and extracted by using solvent system of acetone/ethanol/ hexane (5ml/5ml/10ml). Stirring on ice was done for 15 minutes. 3 ml of deionized water was added after shaking. Samples were shaken for 5 minutes on ice and then left at room temperature for 5 minutes to allow the separation of phases. The lycopene layer were then separated and scanned in UV-VIS spectrophotometer. The results showed that the lycopene concentration ranged from 27 μg/g to 115 μg/g with % relative error ranged from 2.86 to 3.14, the standard error ranged from ± 0.013to ± 0.015,and standard deviation ranged from 7.38 to 29.5.  Both watermelons and tomato varieties contain the appreciable quantities of lycopene which is the significant nutrient for human body in daily life.