Feasibility studies on the thermodynamics of Cr (VI) ions adsorption in aqueous medium by maleic acid red onion skin extract resin (MRER) was undertaken. The acetone extract of red onion skin was used in the synthesis of MRER. The regression analysis of the models at different temperatures and concentrations was found to closely fit the experimental data in the order: Freundlich > Langmuir > Temkin. Investigation of the thermodynamics of adsorption reaction revealed values for the change in enthalpy   (- 34.05414 kJ/mol), Gibbs free energy (-18.001, -17.362, -17.860, -15.809 and -16.154 kJ/mol) and entropy (-52.7839 J/K/mol), which reflected the process spontaneity, exothermic nature and feasible affinity of the interacting metal ions at the adsorption sites. Dubinin-Radushkevich (DR) isotherm was applied in studying the sorption pathway, and it was observed that physisorption is the dominant pathway. Kinetic study showed that pseudo-second order best describe the experimental data with respect to its highest correlation coefficient (R2) values.

The rheological behaviour of drilling mud formulated with sodium hydroxide extracts of Bitter-leaf (BL), Pawpaw (PL), Almond (AL) and Moringa (ML) leaves applied as surfactant (emulsifiers) was studied. The rheological properties (plastic viscosity (PV), yield point (YP), and gel strength) of the mud were measured using standard procedures. The mud specific gravity for BLEM and PLEM was observed to give same value (1.08) as that of the C1 mud. pH of the formulated mud were all alkaline and in the order BLEM (8.6) > PLEM (8.3) > ALEM (8.3) > C1(8.3) > MLEM (8.2) > C2 (8.2). The highest PV (19cP) was recorded by PLEM at 30ºC, while the least value (6cP) was by C2 at 60ºC temperatures. Highest YP (70 1b/100ft2) was recorded by C2 while the lowest YP value (22 1b/100ft2) by C1 both at 30ºC. Gel strength at 10 seconds showed reduction in value as the temperature increased for MLEM, ALEM, C2 and C1 formulated mud and recorded maximum of 45 1b/100 ft2 at 30ºC for C2 while the lowest gel strength was reported by C1 at 60ºC. The results obtained from the study showed that the various alkaline plant extracts used as emulsifying agent have no negative effect on the rheological properties of the formulated mud, rather it enhances the rheological properties even after aging of the mud at 65oC. These results therefore, show the need to use the various plant extracts as alternative additive (emulsifying agent) in the formulation of water based drilling mud.