Michael Horsfall

The use of chemically modified and unmodified cassava waste for the removal of Cd, Cu and Zn ions from aqueous solution

The use of different chemically modified cassava waste biomass for the enhancement of the adsorption of three metal ions Cd, Cu and Zn from aqueous solution is reported in this paper. Treating with different concentrations of thioglycollic acid modified the cassava waste biomass. The sorption rates of the three metals were 0.2303 min(-1) (Cd(2+)), 0.0051 min(-1) (Cu(2+)), 0.0040 min(-1) (Zn(2+)) and 0.109 min(-1) (Cd(2+)), 0.0069 min(-1) (Cu(2+)), 0.0367 min(-1) (Zn(2+)) for 0.5 and 1.00 M chemically modified levels, respectively. The adsorption rates were quite rapid and within 20-30 min of mixing, about 60-80% of these ions were removed from the solutions by the biomass and that chemically modifying the binding groups in the biomass enhanced its adsorption capacity towards the three metals. The results further showed that increased concentration of modifying reagent led to increased incorporation, or availability of more binding groups, in the biomass matrix, resulting in improved adsorptivity of the cassava waste biomass. The binding capacity study showed that the cassava waste, which is a serious environmental nuisance, due to foul odour released during decomposition, has the ability to adsorb trace metals from solutions.

Distribution and partitioning of trace metals in sediments of the lower reaches of the New Calabar River, Port Harcourt, Nigeria.

The distribution of trace metals in sediments of the lower reaches of the New Calabar River, Nigeria was evaluated togetherwith the partitioning of their chemical species between fivegeochemical phases. Samplings were made in five zones at the lower reaches of the New Calaber River. All the trace metals were determined by AAS after selective chemical extractions andconcentrations given in μg gm-1 (dry weight basis). The average totalconcentrations found for trace metals in the sediment were (mean ± rsd.) Pb: 41.6 ± 0.29, Zn: 31.60 ± 0.42, Cd: 12.80 ± 0.92, Co: 92 ± 0.25, Cu: 25.5 ± 0.65 and Ni: 3.2 ± 0.25. Maxima and minima concentrations are inconsistent with previous studies in other rivers of this region. Spatial distribution revealed that the sources of trace metals into theriver appeared to be of non-point. Five contamination indices were applied in studying the partitioning of the trace metals inthe sediment. These indices provided bases for ascertaining the potential environmental risk of trace metals in the river system.The results denote high partition levels in the more mobile andmore dangerous phases.

Arsenolipids show different profiles in muscle tissues of four commercial fish species

Identification of arsenolipids in biological samples is today a challenge and in particular the need for speciation data for toxicological assessment. Fish is one of the major contributors of arsenic in diet. However, the majority of work in this area has only focused on the water soluble compounds. The aim of this study is to provide some data on total arsenic and in particular to gain insights into the types of arsenolipids in the muscle tissues of four commercial and commonly consumed fish species. Determination of total arsenic was carried out by ICP-MS following microwave-assisted acid digestion of the samples and the concentrations found for total arsenic in the muscles ranged from 4.8 to 6.0μg/gd.w. Sequential extraction was carried out using hexane and MeOH/DCM followed by reversed phase HPLC-ICP-MS/ESI-MS analysis of the MeOH/DCM fraction. Eight arsenolipids including three arsenic fatty acids (AsFAs) and five arsenic hydrocarbons (AsHCs) were identified. The result showed that fish with higher arsenolipid (AsLp) content (brill and sardine) are dominated by AsHC, while those with the smaller proportion of AsLp (mackerel and red mullet) have predominately arsenic in the form of AsFA.

Adsorption of Methylene Blue Dye on Pure and Carbonized Water Weeds

ABSTRACT The influence of process variables in batch adsorption has been used to assess the removal of methylene blue dye from aqueous solution using pure and carbonized biomasses of water hyacinth and water spinach. Dried leaves of the water weeds were carbonized at temperature up to 750°C. The optimum removal of dye was achieved at pH 10, 30°C, and 55 min at a dye concentration of 10 mg/L. In an attempt to describe the adsorption process, the equilibrium isotherm for each adsorbent was determined using Langmuir and Freundlich adsorption isotherm models. Maximum adsorption capacities based on the Langmuir model for pure and carbonized water hyacinth were (mg/g) 7.05 and 2.07, respectively, whereas those of pure and carbonized water spinach were 1.25 and 5.32, respectively. It was observed that the equilibrium data were well fit by both the Freundlich and Langmuir isotherms as R 2 > .97. This study demonstrates that the two waterweeds are effective, environmentally friendly, and inexpensive biomaterials for the removal of color from industrial effluents.

Petroleum hydrocarbon pollution: the distribution in sediment and water of the New Calabar River, Port Harcourt, Nigeria

Abstract The hydrocarbon distribution in sediments and water samples of the Port Harcourt segment of the New Calabar River, Nigeria was sampled during the wet and dry seasons of 1990 and 1991. The results demonstrate that a very heterogenous distribution of petroleum hydrocarbon exists in this segment of the river and that the life-style and feeding habits of the organisms in this environment will have a dramatic effect on their hydrocarbon exposure. Site variability indicates that most of the hydrocarbons in sediment and water of the New Calabar River are of anthropogenic origin. The baseline station, BLF, is the least exposed to petroleum hydrocarbon pollution. Seasonal variation gave a high hydrocarbon level during the rainy season which resulted from slow rate of volatilization during this season. Contamination factor, measured as the ratio of the median concentration in the monitoring zones and the median concentration of the baseline values ranged from 1.73 to 8.47 in sediments and 2.02 to 2.62 in water.