Use of nonedible seed pods ofMoringa oleifera(Moringa) tree and nutshells ofSclerocarya birrea(Morula) tree for removal of selected metal ions (lead, cadmium, copper, manganese, iron, zinc, and magnesium) from wastewater and borehole water samples was investigated. Removal parameters such as contact time, pH, temperature, particle size, sorbent dose, and initial metal concentration were optimized. Determination of residual metal ions after employing sorbent was done using flame atomic absorption spectroscopy (FAAS). Using 200 ng synthetic metal ion mixture in 50 mL of water sample, the optimized parameters for Moringa seed pods were 60 min contact time, 1.0 g of sorbent dose, pH 8, 100 μm sorbent particle size, and extraction temp 35°C. While using Morula nutshells, the optimized conditions were 120 min contact time, 2.0 g sorbent dose, pH 8, 100 μm sorbent particle size, and extraction temp of 35°C. The removal efficiency of acid treated sorbents was compared to that of untreated sorbents and it was found to be higher for acid treated sorbents. These nonedible plant parts for Morula and Moringa plants are proposed as a cheap, simple, and an effective alternative for purification of water contaminated with heavy metals.

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in theTerminalia sericeasample obtained from Kasane. The method was validated and the analyte recoveries ranged from69.58±7.20to113±15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R2>0.9900) in the range of 2 to 100 ng g⁻¹. The method also proved to be sensitive with low limits of detection (LODs) ranging from0.48±0.16to1.50±0.50 ng g⁻¹. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants.

Samples of modified and fresh coal from Morupule, in Botswana, were characterized by nitrogen adsorption at 77 K and found to be micro porous materials, with the modified sample having a higher specific surface area (SBET = 282.0 m2/g) which is 19 times that of the original sample. Modification by activation increased the average pore radius slightly. Interaction of the coals with sulphur dioxide, a known pollutant, was investigated through its adsorption at various temperatures to facilitate the determination of isosteric heats of adsorption. The values obtained indicated physical adsorption of the pollutant indicating the possible reuse over and over again to trap and remove the pollutant in gaseous phase. Results from elemental analyser show that Morupule coal contains 68.8%±5.0% carbon.