Comparative Analysis and Regenerative Studies of Alkaline Modified Groundnut Shell as Adsorbent for the Removal of Oil Layer from Polluted Water

Abstract

This work focuses on the comparative analysis and regenerative studies of alkaline modified groundnut shell as adsorbent for the removal of oil layer from water surface. The groundnut shell was carbonized at 800°C before chemical activation. Scanning Electron Microscope (SEM) and UV/VIS Spectrophotometer were used in characterizing the adsorbents. Batch adsorption studies were carried out to determine the effect of process conditions on the percentage removal. Regeneration studies was applied to investigate the reusability of the adsorbent after each batch of experiments. SEM characterization revealed that micro porous space on the surface of the adsorbent (groundnut shell) increased significantly after activation. The surface area of the composite increased from 28.5cm2 to 87.9cm2 after activation. pH of point zero charge ranging from to revealed negative charge predominance on the surface of the adsorbents and adsorption was found to be very fast at low pH due to strong electrostatic force between oil layer and ion diffusion on the adsorbent surface. The optimum adsorption time was found to be 100 minutes with 79.4% oil removal.at pH of 6.9. Regeneration of the adsorbent after each batch of experiments shows that the surface area remained intact at 77.8cm2 which is almost equal to the modified (unused) adsorbent. Experiments with the regenerated adsorbent shows that 84.89% of oil was removed at oil water ratio of 0.2g/100cm3 against 88.56% of oil removed using the modified adsorbent at the same oil water ratio. Thus, the sorption process was feasible, spontaneous, rapid and showed high performance with a proven ability of the adsorbent to be regenerated after use. However, the present approach has the advantage of simplicity, less time consuming and most importantly, low cost considering the availability of groundnut shell at no cost.

Kinetics and Thermodynamics of Sorption of Methylene Blue Dye Onto Raw Groundnut Shell Biosorbent

“…The values of ∆𝐺𝐺 𝑎𝑎𝑑𝑑𝑠𝑠 ° are all negative and increased slightly with an increase in temperature, this indicates enhanced biosorption of MB at moderate temperature and a spontaneous process. However, the positive values of ∆𝐻𝐻 𝑎𝑎𝑑𝑑𝑠𝑠 ° and ∆𝑆𝑆 𝑎𝑎𝑑𝑑𝑠𝑠 ° obtained indicated physisorption, an endothermic process, and increased randomness of the solid−solution interface for the MB biosorption process [16,24,25].…”

“…The values of ks1, ks2, and qe can be obtained from the slope and intercept of the graph. Gibbs free energy change, ΔG, change in entropy, ΔS, and change in enthalpy, ΔH as thermodynamic quantities were evaluated from equations 6 and 7 [24,25]:…”