Adsorption has been widely used for the removal of heavy metals from waste water due to its availability, efficiency, profitability and its low cost of operation. In this study, locust bean seed shell powder prepared from locust been seed shell (LBSS) was used as adsorbent. Batch adsorption experiments were carried out in order to study the effect of process variables such as; adsorbent dosage, time, concentration, and temperature. The adsorbents both unmodified and modified were characterized using SEM, XRF, and FTIR. The results showed structural modification of the modified locust bean seed shell powder (MLBSSP). The adsorption equilibrium data of MLBSSP perfectly conform to Freundlich adsorption model based on its high correlation coefficient which is close to unity (0.9738). However, the kinetic studies showed that the process fit in well into pseudo second order due to its higher R 2 (0.9662) in MLBSSP. The positive values obtained for change in enthalpy indicate that the adsorption process is endothermic in nature while the negative values obtained for change in entropy of the process reveal decrease in the randomness of the process and the positive values of change in Gibb's free energy suggest non spontaneity of the adsorption process. The adsorbent (MLBSSP) shows excellent performance in removing Pb (II) ions from aqueous solutions and can be used as a substitute to the available expensive adsorbents since it is cheap, non-toxic and abundantly available.
The quality and stability of palm kernel oil (PKO) and cottonseed oil (CTSO) as affected by bleaching using modified oyster shell powder (OSP) and periwinkle shell powder (PSP) were evaluated by analysing their physicochemical properties. The two adsorbents potential was improved on by modification using 5 M HCl and H2SO4. The determinations of the parameters were carried out by titration, while the refractive index was determined using a refractometer. The results indicate that the saponification values (SV) of PKO and CTSO increase after bleaching. However, the result further shows that the peroxide values (PV) of bleached PKO using OSP and PSP modified with 5 M HCl decreased (17.49±0.01 and 20.04±0.08 respectively) and also the iodine values decreased (3.15±0.13 and 3.41±0.02 respectively). The same decrease in PV and IV values is observed in PKO bleached using 5 M H2SO4. The values of PV for OSP and PSP are 4.99±0.005 and 12.77±0.77 respectively while the IV values for OSP and PSP are1.85±0.01 and 12.53±0.09 respectively. Also, 5 M HCl and H2SO4 modified OSP and PSP reduced the IV content in CTSO. (5 M HCl OSP and PSP are; 3.15±0.13 and 3.41±0.02 respectively while 5 M H2SO4 OSP and PSP values are; 3.33±0.04 and 3.13±0.06 respectively). The study revealed that the bleaching through the use of OSP and PSP influenced the components and properties of the PKO and CTSO, improved on their qualities and therefore, the adsorbents can serve as alternatives to the costly adsorbents available in the markets.
The study was carried out to investigate the bleaching efficiency of chitosan for pigments removal from palm kernel oil (PKO). Chitosan was synthesized from periwinkle shell waste by chemical technique involving demineralization, deproteinization and deacetylation. The bleaching was carried out (batch process) at various adsorbent dosages (1.0-3.0 g). The bleaching adsorbents (Periwinkle Shell Powder, PSP and chitosan periwinkle shell powder, CPSP) were characterized using X-ray fluorescence (XRF) for their elemental composition, scanning electron microscopy (SEM) for surface morphology and Fourier Transform Infrared (FTIR) was used to observe the presence of functional groups in the samples. The results obtained revealed alteration in the concentration (wt. %) and distribution of different compositional elements. The broad peak at 3272.6 cm-1 and the absence of bands 1744.4, 1628.8, 1461.1 cm-1 in PSP revealed forming and breaking of bonds in PSP and CPSP. The bleaching process was tested with four different adsorption isotherms (Langmuir, Freundlich, Temkin and Dubinin – Radushkevich (D-R). The PSP has the higher percentage bleaching efficiency (66.56) while CPSP has 47.05 using 1.0 g each of the biopolymer however 1/n Freundlich isotherm constants which is an indication of adsorption intensity was higher in CPSP (3.4) compare with PSP (2.68). The adsorption process followed D-R in both CPSP and PSP (R2; 0.827 and 0.988 respectively) the mean free energies (EkJ/mol) of both CPSP and PSP (-35.71 and -12.90 respectively) were less than 8 kJ/mol suggesting physical adsorption.
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