Kayode O. Adebowale

Foaming, gelation and electrophoretic characteristics of mucuna bean (Mucuna pruriens) protein concentrates

Abstract The influences of pH, ionic strength and carbohydrates on the foaming and gelation properties of mucuna bean protein concentrate (MPC) were investigated. The protein concentrate was extracted by alkaline solubilization at pH8, followed by isoelectric precipitation at pH 4. The protein solubility–pH profile showed minimum solubility (19.4%) at pH 4.0 (iso electric point) and maximum solubility (96%) was obtained at pH 12. Foaming capacity increased as the sample concentration increased. Increase in sample concentration also enhanced foaming stability at the various times studied. pH had a pronounced effect on the foaming properties of MPC. At pH 4, MPC exhibited minimum foaming capacity and maximum foaming stability. At lower pH values, there was enhanced foaming capacity and a reduction in the foaming stability. Alkaline media (pH 8 and 10) enhanced foaming but the foams were less stable. Sucrose, maltose, lactose and potato starch improved the foaming capacity and stability of the protein concentrate. Increase in ionic strength, from 0.1 to 0.4 M, improved foaming capacity and stability, while further increase beyond the ionic strength resulted in a reduction of the foaming properties. In all cases studied, gelation improved with increases in concentration of the protein concentrate in the media. Gelation properties were reduced in alkaline and acidic media, except at pH 4, where least gelation concentration endpoint (LGE) was 8. Gelation properties of MPC improved in the presence of carbohydrates in the mixture. Gel-forming properties also increased with increases in ionic strength of the media from 0.1 to 0.4 M, while further increase, from 0.6 to 1.0 M, reduced the gelation properties of MPC. Five polypeptide protein sub-units, at apparent molecular weights of 200, 116, 82, 63, and 59 kDa, were obtained from polyacrylamide gel electrophoresis under non-reducing conditions (without 2-mercaptoethanol). In addition, two other sub-units, at apparent molecular weights of 97 and 40 kDa, were obtained under reducing conditions (with 2-mercaptoethanol).

Equilibrium, kinetic and sorber design studies on the adsorption of Aniline blue dye by sodium tetraborate-modified Kaolinite clay adsorbent

Raw Kaolinite clay obtained Ubulu-Ukwu, Delta State of Nigeria and its sodium tetraborate (NTB)-modified analogue was used to adsorb Aniline blue dye. Fourier transformed infrared spectra of NTB-modified Kaolinite suggests that modification was effective on the surface of the Kaolinite clay with the strong presence of inner -OH functional group. The modification of Kaolinite clay raised its adsorption capacity from 1666 to 2000 mg/kg. Modeling adsorption data obtained from both unmodified and NTB-modified Kaolinite clay reveals that the adsorption of Aniline blue dye on unmodified Kaolinite clay is on heterogeneous adsorption sites because it followed strongly the Freundlich isotherm equation model while adsorption data from NTB-modified Kaolinite clay followed strongly the Langmuir isotherm equation model which suggest that Aniline blue dye was adsorb homogeneous adsorption sites on the NTB-modified adsorbent surface. There was an observed increase in the amount of Aniline blue adsorbed as initial dye concentration was increased from 10 to 30 mg/L. It was observed that kinetic data obtained generally gave better robust fit to the second-order kinetic model (SOM). The initial sorption rate was found to increased with increasing initial dye concentration (from 10 to 20 mg/L) for data obtained from 909 to 1111 mg kg(-1)min(-1) for unmodified and 3325-5000 mg kg(-1) min(-1) for NTB-modified adsorbents. Thereafter there was a decrease in initial sorption rate with further increase in dye concentration. The linearity of the plots of the pseudo-second-order model with very high-correlation coefficients indicates that chemisorption is involved in the adsorption process. From the design of a single-batch adsorber it is predicted that the NTB-modified Kaolinite clay adsorbent will require 50% less of the adsorbent to treat certain volumes of wastewater containing 30 mg/L of Aniline blue dye when it is compared with the unmodified adsorbent. This will be cost effective in the use of NTB-modified adsorbent for the adsorption of Aniline blue dye from water and wastewater.

Isolation, chemical modification and physicochemical characterisation of Bambarra groundnut (Voandzeia subterranean) starch and flour

The proximate and physico chemical characterisation of Bambarra groundnut (Voandzeia subterreanea) flour and starch was studied. Oxidation and acetylation of the native starch reduced the percentage ash, crude protein, crude fibre, and crude fat. The swelling capacity increased with increase in temperature for both starch and flour; the acetylated starch, however, showed the highest swelling power. There is increased swelling and solubility in the alkaline region. Oxidized starch had the highest oil and water absorption capacity (3.04 and 2.40 g/g, respectively). The least gelation concentration for the starches ranged from 6 to 10% (w/v), while the alkaline water retention increased when the starches were blended with wheat flour, with the blends of wheat flour and acetylated starch giving the best result. Brabender viscographic studies showed lowering of pasting temperature after oxidation and acetylation, with oxidised starch showing the lowest pasting temperature. Both oxidation and acetylation lowered the peak viscosity (PV), hot paste viscosity (Hv) and cold paste viscosity (Cv). Chemical modification enhanced the stability of the starches with oxidised starch having the highest stability value, followed by acetylated starch.

Phytoremediation potential of Eichornia crassipes in metal-contaminated coastal water

The potential of Eichornia crassipes to serve as a phytoremediation plant in the cleaning up of metals from contaminated coastal areas was evaluated in this study. Ten metals, As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, V and Zn were assessed in water and the plant roots and shoots from the coastal area of Ondo State, Nigeria and the values were used to evaluate the enrichment factor (EF) and translocation factor (TF) in the plant. The critical concentrations of the metals were lower than those specified for hyperaccumulators thus classifying the plant as an accumulator but the EF and TF revealed that the plant accumulated toxic metals such as Cr, Cd, Pb and As both at the root and at the shoot in high degree, which indicates that the plant that forms a large biomass on the water surface and is not fed upon by animals can serve as a plant for both phytoextraction and rhizofiltration in phytoremediation technology.

Modeling of fixed-bed column studies for the adsorption of cadmium onto novel polymer-clay composite adsorbent.

Kaolinite clay was treated with polyvinyl alcohol to produce a novel water-stable composite called polymer-clay composite adsorbent. The modified adsorbent was found to have a maximum adsorption capacity of 20,400+/-13 mg/L (1236 mg/g) and a maximum adsorption rate constant of approximately = 7.45x10(-3)+/-0.0002 L/(min mg) at 50% breakthrough. Increase in bed height increased both the breakpoint and exhaustion point of the polymer-clay composite adsorbent. The time for the movement of the Mass Transfer Zone (delta) down the column was found to increase with increasing bed height. The presence of preadsorbed electrolyte and regeneration were found to reduce this time. Increased initial Cd(2+) concentration, presence of preadsorbed electrolyte, and regeneration of polymer-clay composite adsorbent reduced the volume of effluent treated. Premodification of polymer-clay composite adsorbent with Ca- and Na-electrolytes reduced the rate of adsorption of Cd(2+) onto polymer-clay composite and lowered the breakthrough time of the adsorbent. Regeneration and re-adsorption studies on the polymer-clay composite adsorbent presented a decrease in the bed volume treated at both the breakpoint and exhaustion points of the regenerated bed. Experimental data were observed to show stronger fits to the Bed Depth Service Time (BDST) model than the Thomas model.

Synthesis of covalently bonded graphene oxide–iron magnetic nanoparticles and the kinetics of mercury removal

Synergistically combined nanomaterials have been applied in various fields in materials science to improve the properties of nanocomposites. However, limited studies focus on the ability of such composites for water treatment. A graphene oxide (GO)–iron oxide (Fe3O4) magnetic nano-particle composite (GOMNP) was synthesized and used to study the Hg2+ adsorption kinetics from aqueous solution at various temperatures. GO was attached to magnetic nanoparticles via the amine group of 3-aminopropyltriethoxysilane which was attached the surface of Fe3O4. The GOMNP nano-composite had a Hg2+ adsorption capacity of 16.6 mg g−1. IR spectra analysis showed that hydroxyl and carboxylate functional groups were mainly responsible for Hg2+ adsorption. Adsorption of Hg2+ by the GOMNP obeyed different adsorption mechanisms at varying adsorption temperatures. The Elovich kinetics model described the Hg2+ adsorption data better than any of the other three models tested. The GOMNP nano-composite is thus a promising nanosorbent for Hg2+ removal from aqueous solutions.

Physicochemical properties, morphological and X-ray pattern of chemically modified white sorghum starch. (Bicolor-Moench).

Starch isolated from white sorghum was subjected to chemical modifications like oxidation, acetylation and acid thinning. Proximate composition of these, such as crude protein, crude fat, moisture content and ash content were studied. Wide angle X-ray diffractograms showed typical ‘A’ pattern characteristic of cereal starches, but significant differences were observed between the X-ray pattern of native and modified starches. Scanning electron microscopy revealed round and polygonal shapes for the starch granules with heterogeneous sizes and chemical modifications altered the starch granules morphology. Swelling power and solubility increased with increasing in temperature. Swelling power increased upon acetylation but decreased during acid thinning and oxidation. Solubility increased in these three modifications compared to the native starch.

Fuzzy comprehensive assessment of metal contamination of water and sediments in Ondo Estuary, Nigeria

A more reliable methodology for evaluating metal contamination of coastal water and sediments using fuzzy comprehensive assessment (FCA) is presented by this study. Ten metals (As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, V and Zn) were investigated in water and sediments from ten sampling sites and formulated into fuzzy matrix based on three contamination classifications of pristine, moderately enriched and extremely impacted categories using regulatory limits as criteria. The products of the matrices from membership function of the observed data and the weight matrices generate indices that classify the degree of metal impact on the sites. The results of the FCA show that the estuary is negatively impacted by metals in a range of 45.5–75.1% membership in the extremely impacted category with potential adverse effects on the ecosystem of the neighbouring Atlantic Ocean. The crude oil exploration activity at site 1 is the major source input of the metals beside Fe and Mn which are natural to the geological structure of the area while domestic waste discharges contribute notably to metal contamination in some sites.

Removal of Lead and Cadmium Ions from Aqueous Solution by Polyvinyl alcohol-modified Kaolinite Clay: A Novel Nano-clay Adsorbent

Kaolinite clay was modified with polyvinyl alcohol (PVA) to obtain a PVA–nano-clay adsorbent. X-Ray diffraction measurements of the adsorbent showed no observable change in the d-spacing of its crystal lattice. Scanning electron microscopy of the PVA-modified nano-clay adsorbent indicated the presence of irregular crystal structures. Infrared spectroscopy suggested that the PVA–nano-clay adsorbent basically possessed outer –OH functional groups. This adsorbent was found to have an adsorption capacity of 56.18 mg/g for Pb2+ ions and 41.67 mg/g for Cd2+ ions. The adsorption data obtained was well explained by the Diffuse Layer Model (DLM), which implies that the adsorption of both metal ions onto the modified adsorbent was via an inner-sphere surface complexation mechanism. The ΔH0 values for the adsorption of both metal ions onto the PVA–nano-clay were −12.48 kJ/mol for Pb2+ ions and −13.49 kJ/mol for Cd2+ ions, with both ions exhibiting negative adsorption entropies. Data-fitting indicated that both the PVA–nano-clay and the unmodified adsorbent possessed homogeneous and heterogeneous adsorption sites. Virtually complete desorption (ca. 99%) of both metal ions occurred from PVA–nano-clay within 3 min.

Competitive biosorption of Pb(II) and Cd(II) ions from aqueous solutions using chemically modified moss biomass (Barbula lambarenensis)

Treatment of biosorbents to add functional groups that increase toxic metal biosorption is an important way to improve its effective application. Hence, different portions of pristine Barbula lambarenensis (RBL) were treated separately with sodium tripolyphosphate (TPP) and ethylene glycol. The pristine and treated RBL biomasses were used to evaluate the simultaneous removal of Pb(II) and Cd(II) from aqueous solutions. Equilibrium, kinetics and adsorption isotherms were studied. Results revealed that biosorption of Pb(II) and Cd(II) metal ions were spontaneous and described by the pseudo-second-order kinetics. TPP-treated RBL showed higher biosorption capacity for Pb(II), while the ethylene glycol-treated adsorbent was more efficient for Cd(II) biosorption. The simultaneous presence of Pb(II) and Cd(II) in solution did not affect Pb(II) biosorption. However, Cd(II) biosorption dropped 44, 42 and 19% for the pristine, ethylene glycol and TPP-treated adsorbents, respectively, in the competitive adsorption. Both treatments enhanced Pb(II) and Cd(II) biosorption by RBL.