Adsorption of phosphate from domestic wastewater treatment plant effluent onto the laterites in a hydrodynamic column

High concentration of phosphate (PO4

Cyclic voltammetric study of aflatoxin G1 at the mercury electrode

A cyclic voltammetry (CV) study of aflatoxin G1 (AFG1) in Britton-Robinson buffer (BRB) using a control growth mercury electrode (CGME) is described. CV was carried out by anodic and cathodic potential scan over the range of 0 to -1500 mV with no accumulation time. The effect of the different scan rates and pH of BRB on the peak height and peak potential of the analyte were also studied. The results from this study showed that the reduction process on the hanging mercury electrode gives a single characteristic cathodic peak at -1184 to -1246 mV ( versus Ag/AgCl ) in BRB pH of 3.0 to 10.0. The BRB pH of 9.0 was noted as the best condition for the detection of AFG1 as the peak gives a maximum peak current. Effect of the scan rate and pH of BRB on both responses has shown that the reduction of AFG1 is irreversible, pH dependent and the limiting current is adsorption controlled

Characterization of poly(vinyl alcohol)- polycaprolactone hybridized scaffold for potential skin tissue regeneration

The fabrication of a hybridized scaffold constituting hydrophobic and hydrophilic polymers for tissue engineering has received an increasing attention recently. Due to the high compatibility with water, a hydrophilic polymer, though is able to enhance cell affinity and proliferation, has a very high biodegradable rate and low stability in aqueous medium that eventually puncture its biomedical applications. Thereby, the addition of a hydrophobic polymer in the hydrophilic polymer scaffold is recommended to increase the hydrophobic property of the scaffold in order to reduce the limitation. Nonetheless, the fabrication of the hybridized scaffold is extremely challenging because the hydrophilic and the hydrophobic polymer tends to dissolve in different types of solvents, i.e. water and organic solvent, respectively, that subsequently restricts their blending process. In this work, a poly(vinyl alcohol) (PVA) scaffold, a polycaprolactone (PCL) scaffold, and their hybridized scaffold were produced through casting method for potential skin tissue regeneration. We found that the glacial acetic acid was an appropriate solvent used to prepare hydrophobic PCL solution with low molecular weight (16 kDa) for PCL-PVA blend, with mass ratio 1:1, without using any surfactant. The solvent was also used for the preparation of PCL scaffold with high molecular weight (80 kDa). The fabricated polymer scaffolds were then evaluated using FTIR-ATR, contact angle measurement, and tensile strength analysis. FESEM images of the PVA-PCL hybridized scaffold showed that the PCL was well dispersed in the PVA scaffold. FTIR-ATR spectra showed that the hybridized scaffold exhibited the crucial functional group of PVA and PCL at 3310.97, 1720.10, 1557.80, 1241.69, 1172.90, 1044.95, and 719.44 cm-1. The contact angle of the PVA, PCL, and PVA-PCL hybridized scaffold were 61.3o, 82.7o, and 75.9o, respectively, with tensile strength 16.5747, 2.4038, and 7.417 MPa, respectively

Solution parameter effect on polysulfone fibers via electrospinning: fabrication, characterization and water flux property

This research investigates the solution parameters, i.e., polymer concentration and addition of manganese (IV) oxide (MnO2) nanoparticles, for the fabrication of polysulfone (PSF) fibers via electrospinning. Initially, PSF was dissolved in N,N-dimethylformamide (DMF) solvent and electrospun fibers with different morphologies were obtained using the range of PSF concentration of 10% (w/v) to 25% (w/v). Subsequently, PSF with the concentration of 20% (w/v) (denoted as PSF(20%)) was chosen to blend with 0.2% (w/v) of MnO2 as it gave the most stable electrospinnability and uniform fiber diameter. The fabricated electrospun PSF(20%) and PSF(20%)-MnO2 fibrous membranes were characterized to determine the morphology, wettability property, zeta potential, and tensile strength. The presence of MnO2 improved tensile strength as it reduced the fiber diameter that eventually made a more compact fiber mat membrane. The results of contact angle confirmed that the fabricated fiber exhibited more hydrophobic property in the presence of MnO2 nanoparticles. Thus, it reduced the pure water flux of PSF fiber membrane. The more hydrophobic nature of the proposed nanofiber might be useful in enhancing the application of PSF fiber in oil-water separation process

Effects of glucose on the Reactive Black 5 (RB5) decolorization by two white rot basidiomycetes

The capacities of glucose in the decolorization process of an azo dye, Reactive Black 5 (RB5), by two white rot basidiomycetes, Pleurotus sp. F019 and Trametes sp. F054 were investigated. The results indicated that the dye degradation by the two fungi was extremely correlated with the presence of glucose in the culture and the process of fungi growth. Decolorization of 200 mg dye/l was increased from 62% and 69% to 100% within 20-25 h with the increase of glucose from 5 to 15 g/l, and the activity of manganese dependent peroxidase (MnP) increased by 2-9 fold in this case. Hydrogen peroxide of 0.55 mg/l and 0.43 mg/l were detected in 10 h in Pleurotus sp. F019 and Trametes sp. F054 cultures

Fabrication and characterization of polyvinylidene fluoride composite nanofiber membrane for water flux property

This research is about the investigation of the pure water flux property of composite polyvinylidene fluoride (PVDF) nanofibers. Electrospinning technique was used to prepare the composite electrospun nanofibers. PVDF was dissolved in N,N-dimethylformamide (DMF) solvent and blended together with activated carbon (AC) and polyvinylpyrrolidone (PVP). The nanofibers were characterized to determine the morphologies, wettability property, and its tensile strength. The fabricated nanofibers diameter was found in the range between 20 to 180 nm. The presence of AC deteriorates the mechanical properties of the nanofibers as the size of AC is larger than the external diameter of the nanofibers. The results of contact angle confirmed that the fabricated nanofiber exhibit less hydrophobic in the presence of PVP and AC. The less hydrophobi

Interpretation of isotherm models for adsorption of ammonium onto granular activated carbon

High amounts of ammonium (NH4+) discharged in receiving water can lead to eutrophication. The adsorption of NH4+ from synthetic solution onto granular activated carbon (GAC) was scrutinized with respect to initial solute concentration (10 mg L-1 ), solution volume (0.2 L), adsorbent dosage (4 – 20 g), and contact time. Experimental data can be well described by the pseudo-second-order kinetic model (R2 > 0.994) and Freundlich isotherm model (R2 = 0.936), suggesting that chemisorption and multilayer adsorption occurred. Furthermore, this study explored the feasibility of using the Freundlich isotherm model to estimate the removal efficiency or required amount of adsorbent. The result findings indicated that GAC has a good potential to adsorb NH4+ from water and thus giving new insights into environmental engineering practices

Phosphate removal from wastewater in batch system using waste mussel shell

High input of phosphate (PO43–) in rivers can lead to eutrophication, which jeopardizes aquatic life and human health. In this study, PO43– was removed from synthetic solution and domestic wastewater treatment plant effluent (DWTPE) by waste mussel shell (WMS). The PO4 3– adsorption by WMS was examined for the initial PO4 3– concentration (7 mg L-1), solution volume (0.2 L), adsorbent dosage (4, 8, 12, 16, and 20 g), and contact time (1-6 d). The batch experiment's optimum performance could reach approximately 75.1% for the removal of PO4 3– from synthetic solution and approximately 66.2% for the removal of PO43– from DWTPE after a contact time of 5 d. This work suggests that the WMS can remove PO43 from both synthetic solution and DWTPE. Future works are necessary to increase WMS's capacity to adsorb PO4 3– from waters, either by physical or chemical modification

Electroanalytical studies of aflatoxins - stripping voltammetric methods for the determination of aflatoxin compounds

Aflatoxin, which is produced by Aspergillus flavus and Aspergillus parasiticus fungi is one of the compounds in the mycotoxin group. The main types of aflatoxins are AFB1, AFB2, AFG1 and AFG2 which have carcinogenic properties and are dangerous to human health. Various techniques have been used for their measurements such as the high performance liquid chromatography (HPLC), enzyme linked immunosorbant assay (ELISA) and radioimmunoassay (RIA) but all these methods have disadvantages such as long analysis time, consume a lot of reagents and expensive. To overcome these problems, the voltammetric technique was proposed in this study using controlled growth mercury drop (CGME) as the working electrode and Britton Robinson buffer (BRB) as the supporting electrolyte. The voltammetric methods were used for investigating the electrochemical properties and the quantitative analysis of aflatoxins at the mercury electrode. The experimental conditions were optimised to obtain the best characterised peak in terms of peak height with analytical validation of the methods for each aflatoxin. The proposed methods were applied for the analysis of aflatoxins in groundnut samples and the results were compared with those obtained by the HPLC technique. All aflatoxins were found to adsorb and undergo irreversible reduction reaction at the working mercury electrode. The optimum experimental parameters for the differential pulse cathodic stripping voltammetry (DPCSV) method were the BRB at pH 9.0 as the supporting electrolyte, initial potential (Ei): -0.1 V, final potential (Ef): -1.4 V, accumulation potential (Eacc): - 0.6 V, accumulation time (tacc): 80 s, scan rate: 50 mV/s and pulse amplitude: 80 mV. The optimum parameters for the square wave stripping voltammetry (SWSV) method were Ei = -0.1 V, Ef = -1.4 V, Eacc: -0.8 V, tacc: 100 s, scan rate: 3750 mV/s, frequency: 125 Hz and voltage step: 30 V. At the concentration of 0.10 µM, using DPCSV method with the optimum parameters, AFB1, AFB2, AFG1 and AFG2 produced a single peak at -1.21 V, -1.23 V, -1.17 V and -1.15 V (versus Ag/AgCl) respectively. Using the SWSV method, a single peak appeared at -1.30 V for AFB1 and AFB2 while -1.22 V for AFG1 and AFG2. The calibration curves for all aflatoxins were linear with the limit of detection (LOD) of approximately 2 0 ppb and 0.50 ppb obtained by the DPCSV and SWSV methods respectively. The results of aflatoxins content in individual groundnut samples do not vary significantly when compared with those obtained by the HPLC technique. Finally, it can be concluded that both proposed methods which are accurate, precise, robust, rugged, fast and low cost were successfully developed and are potential alternative methods for routine analysis of aflatoxins in groundnut samples