Investigation of the sorption potential of rice husk, an agricultural waste, as an adsorbent was carried out. The rice husk was modified with orthophosphoric acid and was used for adsorption of lead (II) ions (Pb 2+ ) from aqueous solution. Physicochemical properties of the modified rice husk were determined. Equilibrium sorption data were confirmed with Langmuir, Freundlich and Temkin adsorption isotherms. On the basis of adsorption isotherm graphs, R 2 values were determined to be 0.995, 0.916, and 0.797 for Langmuir, Temkin, and Freundlich isotherms, respectively, indicating that the data fitted well into the adsorption isotherms, but Langmuir isotherm is a better model. The maximum monolayer coverage from Langmuir studies, max = 138.89 mg/g, Langmuir isotherm constant, = 0.699 L/mg, and the separation factor, = 1.41 × 10 −2 at 100 mg/L of lead(II) ions indicating that the sorption process, was favourable. The suitability of modified rice husk as an adsorbent for the removal of lead ions from aqueous solution and its potential for pollution control is established.

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This study estimates the contribution from the open burning of municipal wastes in some of Nigeria's major cities to atmospheric levels of air pollutants. Information obtained on open burning emission factors and municipal solid waste (MSW) generation estimates was combined to estimate annual levels of the pollutants from the open burning of MSW. Per capita distributions of pollutants were calculated on the basis of cities’ populations. The estimates of inorganic emissions across the cities studied were from 913.73 to 81,600 tons per year (TPY) of particulate matter; 4,797 to 428,400 TPY of oxides of nitrogen; 342.65 to 30,600; and 57 to 5,100 TPY of sulfur dioxide, while the estimates for methane ranged from 742 to 66,300 TPY and for other nonmethane organic compounds ranged from 1,713 to 153,000 TPY. Given the composition of MSW in these cities, the nonmethane organic compounds are likely to be composed of polycyclic aromatic hydrocarbons and volatile organic compounds. Given the wide varieties of both inorganic and organic air pollutants released during the open burning of MSW and the associated human health and environmental impacts, it is high time that stakeholders at all levels of government came up with policies and regulatory measures for the management of MSW in the country.

The review article reflects on the potential of silica aerogel as viable absorbents for spilled crude oil. Reported oil absorption capacity of silica aerogel shows it has a future in polluted site clean-up. The review presents the various dynamics of oil spill, conventional clean-up technologies and silica aerogel synthesis techniques. It also highlights some investigations of oil spill sorption using aerogels. The future prospect of rice husk as a cheaper source silica aerogel is also considered.

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