This study investigated groundwater quality collected from two industrial and residential locations in each of Lagos metropolis. Prescribed standard procedures of American Public Health Association were used to measure physico-chemical parameters of each of the groundwater samples which include pH, EC, DO, TDS, BOD, COD, anions (Cl − , NO 3 − , SO 4 2− , PO 4 3− ) and heavy metals (Cu, Zn, Pb, Mn, Fe, Co, Cd and Cr). From laboratory analysis, measured physico-chemical parameters were within the permissible ranges specified by the WHO and NSDWQ except pH, TDS, EC, Pb, Mn and Fe for groundwater samples from industrial locations and pH, Pb, Mn and Fe for residential locations. Higher concentrations of TDS and EC reported for groundwater samples from industrial locations were attributed to heavy discharge of effluents from industrial treatment plants as well as dissolution of ionic heavy metals from industrial activities of heavy machines. Statistical Pearson's correlation revealed physico-chemical parameters of water quality to be moderately and strongly correlated with one another at either p < 0.05 or < 0.01.

This study examined the potential for a composite of snail shell–rice husk (SS‐RH) to successfully remove brilliant green dye (BGD) from aqueous solutions using the batch adsorption method. The adsorbent was synthesized by the calcination process and prepared at a calcination temperature, calcination time, and SS‐RH mixing ratio of 681.10°C, 2.61 hours (h), and 2.61 mixing ratio, respectively. The SS‐RH active functional groups were characterized by the Fourier transform infrared (FTIR) spectroscopy, while examination of its surface morphology was executed by scanning electron microscope. The effects of the BGD's initial concentration, time, pH, solution temperature, adsorbent mass dosage, and rotation speed of the stirrer on it removal were examined. The Langmuir and Sip isotherms fit well for the BGD uptake onto the SS‐RH among the two‐parameter and three‐parameter isotherms examined with R2 values of 0.9995 and 1,000, and optimum adsorption capacities of 129.87 and 123.30 milligrams per gram (mg/g), respectively. Experimental data conformed perfectly using a pseudo‐second‐order kinetic model. The thickness of the boundary layer contributed to the adsorption, as revealed by mechanistic parameters. Thermodynamic adsorption parameters suggested that BGD adsorption onto the SS‐RH was nonspontaneous and endothermic, exhibiting a high level of disorderliness at the solid–liquid interface. The results proved SS‐RH to be a valuable, low‐cost adsorbent for BGD adsorption from aqueous solution.

The optimum preparation conditions for composite snail shell‐rice husk (SS‐RH) adsorbent that gives the optimum brilliant green dye (BGD) uptake has been found at a calcination temperature of 681.10°C, a calcination time of 2.61 hours, and a mixing ratio of 2.61 snail shell‐rice husk, leading to a 97.78% BGD uptake using Central Composite Design. The SS‐RH adsorbent characterization was executed before and after adsorption using a scanning electron microscope (SEM), energy‐dispersive x‐ray spectroscopy (EDS), and Fourier‐transform infrared spectroscopy (FTIR). The SEM image before adsorption showed a highly porous, uniform matrix formation with wide cavities resulting from favorable preparation by calcination at optimum conditions, whereas the image revealed complete adsorption of the BGD onto the vacant pores of the calcined SS‐RH after adsorption. EDS analysis revealed formation of active metal oxides on the surface of the composite SS‐RH was enhanced by the calcination process before adsorption, while changes in their weight percent were noticed after adsorption, showing the influence of the active metal oxides on the process. FTIR revealed the existence of functional groups on the SS‐RH surface, which can interact with the BGD molecules to enhance effective adsorption and cause a shift in the values of the wavenumbers of broad peaks before and after adsorption, respectively. In conclusion, the results obtained have proven SS‐RH to be a valuable composite adsorbent for BGD adsorption.

Abstract:The smoked food samples (Smoked fish, roasted yam, sharwama, suya, roasted plantain and roasted corn) were sampled from retail outlets in Lagos State, Nigeria. The analysis was carried out with a Gas Chromatography (GC) -Flame Ionization Detector (FID) equipped with auto sampler. The results of sixteen PAHs in the studied smoked food shows that PAHs of low molecular weight such as acenaphthene and anthracene were detected in all the food samples. High molecular weight PAHs such as fluoranthene, pyrene and benzo (a) anthracene were also detected. Five and six membered ring PAHs benzo (k) fluoranthrene, benzo (a) pyrene, indenol (1, 2, 3) perylene, dibenzo (a, h) anthracene and benzo (g, h, i) perylene were not detected in all the food samples. Total PAHs concentrations determined in smoked food samples were: smoked fish 0.3303 Mg/Kg, roasted yam 0.2456 Mg/Kg, sharwama 0.4508 Mg/Kg, suya 0.4762 Mg/Kg, roasted plantain 0.1844 Mg/Kg and roasted corn 0.1719 Mg/Kg. The sum of the total fraction of PAHs in smoked food samples calculated according to their rings number and percentage. A two-ring PAHs (naphthalene) was not detected in all the samples except in roasted plantain with 20.6%. A three-ring PAHs recorded the highest percentage of the total PAHs constituting 87.2% in smoked fish, 43.8% in roasted yam, 81.9% in sharwama, 83.3% in suya, 37.5% in roasted plantain and 67.4% in roasted corn. While a four-ring PAHs constitute 12.8% in smoked fish, 56.2% in roasted yam, 18.1% in sharwama, 16.7% in suya, 41.9% in roasted plantain and 32.7% in roasted corn.

<p><strong>Abstract.</strong> This study investigated ground water quality collected from two industrial and residential locations each of Lagos metropolis. Prescribed standard procedures of American Public Health Association (APHA) were used to measure physico-chemical parameters of each of the ground water samples which include pH, EC, DO, TDS, BOD, COD, anions (Cl^&amp;minus;, NO₃^&amp;minus;, SO₄^&amp;minus;, PO₄^&amp;minus;) and heavy metals (Cu, Zn, Pb, Mn, Fe, Co, Cd and Cr). From laboratory analysis, measured physico-chemical parameters were within the permissible ranges specified by WHO and NSDWQ except pH, TDS, EC, Pb, Mn and Fe for ground water samples from industrial locations and pH, Pb, Mn and Fe for residential locations. Higher concentrations of TDS and EC reported for ground water samples from industrial locations were attributed to heavy discharge of effluents from industrial treatment plants as well as dissolution of ionic heavy metals from industrial activities of heavy machines. Statistical Pearson’s correlation revealed physico-chemical parameters to be moderately and strongly correlated with one another at either p&amp;thinsp;˂&amp;thinsp;0.05 or ˂&amp;thinsp;0.01. In conclusion, ground water samples from residential locations are more suitable for drinking than those from industrial locations.</p>