The effect of environmental parameters on contaminant uptake by a passive sampler device

A passive sampling device previously developed was used to assess environmental contamination. It consists of a polymeric bag filled with an organic solvent in which contaminants are preconcentrated after passively diffusing from the water column. The contents of the device were subjected to analysis without further cleanup. The effect of temperature, turbulence, ionic strength, pH, and the presence of dissolved organic material on the partioning process were examined. The results showed that increase in temperature supply the molecules with greater energy and enables them to pass through the membrane and into the solvent. Turbulence was found to disrupt the boundary layer formed around the device as a result of concentration polarization causing irregular fluctuations in the concentration of contaminants in equilibrium with the membrane. There was no discernable correlation between the concentration of contaminants accumulated by the devices and the ionic strength of the incubation solution. There was also no discernable relationship between pH and contaminants uptake by the sampling devices as was expected with non polar, non-ioniseable solutes. The uptake of compounds with lower molar volumes was most susceptible to the presence oh humic materials. Journal of Applied Sciences and Environmental Management Vol. 10(1) 2006: 15-2

Simultaneous phosphates and nitrates removal from waste-waters by electrochemical process: Techno-economical assessment through response surface methodology

In this study, a new multiobjective optimization of the simultaneous removal of phosphates and nitrates by electrocoagulation was studied using the Box-Behnken design. Ten aluminium electrodes, connected in a monopolar configuration in a batch reactor, were immersed in synthetic wastewater and then in real wastewater. The optimal conditions and the effects of parameters (current intensity, electrolysis time and initial pH) on phosphate and nitrate removal, the formation of by-products, and the operating cost were assessed in the case of synthetic wastewater. This optimization allowed to eliminate 89.21 % of phos­phates, 69.06 % of nitrates with an operating cost of 3.44 USD m-3 against 13.67 mg L-1 of ammonium generated. Optimal conditions applied to real domestic wastewater made it possible to remove 93 % of phosphates and 90.3 % of nitrates with an ammonium residual of 30.9 mg L-1. The addition of sodium chloride reduced the residual ammonium content to 2.95 mg L-1. Further, XRD analysis of the sludge showed poor crystal structure and the FTIR spectrum suggested that the phosphate is removed by adsorption and co-precipitation

Lead concentrations in sediments and mollusc gastropod from Vridi Canal, Côte d’Ivoire

Lead (Pb) is one of the most frequent and toxic contaminant in the environment. It can be bioaccumulated by marine organisms through contaminated sediments as well as their food chains. The current study aimed at investigating Pb occurrence in the sediments and gastropod P. haemastostoma from Vridi Canal. Sediment samples were taken using a Van Veen steel grab of 0.02 m2 area, sealed in plastic bags and transported to the laboratory at 4 °C. Gastropod P. haemastostoma species were collected manually using gloves, and then placed in polyethylene plastic bags. The different concentrations were determined using atomic absorption spectrometer Varian AA 20. The results showed seasonal variability of Pb concentrations in sediments and P. haemastostoma. In the both matrices, Pb exhibited the same trend in the distribution between the seasons. This study also mentioned that sediments were highly  contaminated by Pb (54.27-134.71 mg/kg). Vridi Canal was found to be one of the most contaminated seaport area. Pb levels  (49.55-104.19 mg/kg) in P. haemastostoma exceeding the maximum permitted levels according to the United Nations Food and Agriculture Organization (FAO). This research demonstrated that sediments having lower ecological risk may be resulting in lower tissue Pb of P. haemastostoma. Keywords: Metal Pb, sediment, P. haemastostoma, seasonal variatio

Removal of Methylene Blue in aqueous solutions by Electrocoagulation process: Adsorption, Kinetics, studies

The purpose of this study is to understand the mechanism driving the removal of methylene blue through electrocoagulation process. Experiments were carried out using iron as anode and cathode in a batch electrochemical cell operated in a monopolar configuration. The effects of operating parameters (initial pH, current density, initial dye concentration and energy consumption) on the removal of methylene blue from solution were investigated. The results showed that the optimum removal efficiency of 93.2% was achieved for a current density of 9.66 mA/cm2, optimal pH of 8±0.01 with a specific energy consumption of 7.451 kWh/m3. Afterwards, first and second-order rate equations were successively applied to study adsorption kinetics models. On top of usual correlation coefficients (r2), statistical test Chi-square (χ2) were applied to evaluate goodness of fit and consequently find out the best kinetic model. Results showed that MB adsorption process onto iron hydroxides formed in aqueous solution during electrocoagulation treatment followed a second-order kinetic

Bivalve shells ( Corbula trigona ) as a new adsorbent for the defluoridation of groundwater by adsorption-precipitation

International audienc

Optimization of the phytoremediation conditions of wastewater in post-treatment by Eichhornia crassipes and Pistia stratiotes : kinetic model for pollutants removal

International audienc

Efficiency of the heterogeneous catalyst from electrocoagulation sludge for the removal of methylene blue in the presence of persulfate

International audienc

Cocoa Pod Husks as Potential Sources of Renewable High-Value-Added Products: A Review of Current Valorizations and Future Prospects

Cocoa is among the most cultivated and important tropical crops in the world, and it is economically viable in the agro-pastoral systems of tropical Africa. Further, the amount of cocoa residue is steadily increasing due to the strong worldwide demand for chocolate products. This review of cocoa residue found that an average of 18 publications per year were published in the last 10 years. The most common type of publication on cocoa pod husks (CPH) was newspaper articles, which comprised 50% of the publications. This review examines the use of CHP in sustainable development, agrochemical materials, and agro-materials through their potential valorizations into high value-added products. Indeed, CPH is an abundant, accessible, and renewable resource of bioproducts, dietary fibers, nutraceuticals, functional foods, pectin, antioxidant compounds, theobromine, and minerals. Potential food applications of CPH include the production of flavor compounds, gums, texturing agents, and others. The production of biomaterials for food and non-food use, biofuels, and organic acids, such as lactic acid (the polymerization of which produces the PLA used in bioplastic production), are several potential areas for the biotechnological development of CPH and its fractions

Use of plantain peel adsorbents for the reduction of carbon monoxide from biogas for use as chick heating energy in an egg production industry

This research is a case study for the search for an alternative energy to natural gas for heating the chicks of the Brin Foundation located in Yaokokro (Ivory Coast). Specifically, this study aims to reduce carbon monoxide in biogas using biochar and activated carbons prepared from plantain peels. The challenge is to use the purified biogas as an alternative energy source for heating the chicks. Three adsorbents from plantain peel were produced and characterised: 1-Biochar (BC), 2- Potassium hydroxide activated carbon (AC-K) and 3-iron oxide functionalized activated carbon (AC-Fe). Subsequently, their adsorption capacity on carbon monoxide was evaluated. The values obtained for carbonisation yield, moisture and ash content show that the raw material used is suitable for the production of activated carbon biochar. In addition, the surface morphology allows the observation of asperities on the surface of the adsorbents which can be either macropores, mesopores or micropores. The adsorption curves showed that AC-Fe has the longest saturation time of 615 minutes compared to 191 minutes and 188 minutes for BC and AC-K respectively. Furthermore, BC, AC-K and AC-Fe have absorption capacities of 0.77, 0.84 and 3.79 mgCO/g respectively. AC-Fe has a 4.9 times higher adsorption capacity than BC and 4.5 times higher than AC-K. The same case is observed for the percentage of CO removal: 6.9%, 59.83% and 79.19% for BC, AC-K and AC-Fe respectively. According to the efficiency of the adsorbents, they can be classified in the following order: BC < AC-K < AC-Fe. Thus, among the adsorbents used, AC-Fe has the best adsorption capacity and the longest saturation time