36 research outputs found
Selective and Simultaneous Removal of Ni (II) and Cu (II) Ions from Industrial Wastewater Employing a Double Ni-Cu-Ion Imprinted Polymer
In this paper, a Ni-Cu ion imprinted polymer was synthesized and employed for the simultaneous removal of high levels of copper (II) and nickel (II) ions from wastewater. Bulk polymerization technique employing methacrylic acid, ethylene glycol dimethylacrylate, azobisisobutyronitrile as the functional monomer, cross linker and initiator respectively was used to synthesize the ionic imprinted polymer. Rigorous template removal was conducted employing increasing hydrochloric acid concentration ranging from 1.0 M to 10.0 M. The chemical characteristic of the prepared polymer was evaluated by employing Fourier Transform Infrared Spectroscopy. Adsorption parameters including contact time, pH and prepared polymer dosage were investigated and found to be 12 min, 7.0 and 665.5 mg/L respectively. The prepared Ni-Cu ions imprinted polymer showed excellent copper (II) and nickel (II) ions removal efficiency from wastewater as indicated by the 89.1% and 83.2% at n = 3 removal of total copper (II) and nickel (II) ions in the wastewater sample
Removal of Excess Toxic Chloride and Fluoride Anions from Wastewater Employing Eggshells Waste Remains
Eggshells waste was investigated for its sorption abilityas an environmentally-friendly and cheap sorbent for removing excess anions from wastewater. The milled size of the waste was found to be ≤63 µm, with round and smooth morphology. Moreover, the Fourier transform infrared spectrometer spectrum showed functional groups such as carbonate and hydroxyl. The X-ray diffractogram of the eggshells showed the presence of calcite, which mostly compose of calcium and carbonate ions. Multivariate methodology was employed for optimization of factors that affect sorption studies; initial ions concentration which was found to be 24.45 and 23.24 mg/L, the sorbents dose which was found to be 85.20 and 81.56 mg/L, contact time, which were found to be 69.37 and 70.28 min and solution pH 7.19 and 7.97 for chloride and fluoride anion respectively. The eggshells also exhibited high percentage removal efficiencies for chloride (80.70% ± 2.01%) and fluoride ion (93.18% ± 1.67%) from real wastewater samples. The adsorption isotherm was satisfactorily fitted with Langmuir isotherm model. The thermodynamics kinetics studies showed that the adsorption of fluoride and chloride ions onto the eggshells was endothermic and spontaneous and the adsorption data followed second-order kinetics supporting that chemisorption process was involved
Accounting for water use by wildlife–conceptual and practical issues and a case study from Botswana
Use of water by wildlife is not explicitly considered in any part of the System of Environmental-Economic Accounting (SEEA). However, wildlife uses water and in some cases this may be in conflict with other water uses (e.g. irrigation). To examine the magnitude of this problem and the conceptual and practical challenges of including wildlife water use in the SEEA, estimates of water use for 31 mammals in Botswana were developed using readily available data on their abundance and coefficients of water use. Three recording options were considered for the physical supply and use tables: (1) water use by wildlife shown in a new column entitled “Wildlife”; (2) shown as a use by industry under “Operation of nature reserves” and; (3) the preferred option, shown as a split between the first two options, reflecting the location of wildlife inside or outside national parks. The key conceptual issue for recording is the delineation of the production boundary, determined in this case by the extent to which wildlife is deemed managed and hence akin to a cultivated resource in the SEEA. Despite some data limitations, wildlife water use in Botswana was significant, with 21 species accounting for 19,345 ML in 2012–13, equivalent to 10% of the previously estimated water consumption in that year. Water account producers now have clear options for including wildlife, providing water planners and wildlife managers with improved information to help balance competing demands for water that may occur at particular times and places
Development of molecularly imprinted polymer based solid phase extraction sorbents for the selective cleanup of food and pharmaceutical residue samples
This thesis presents the development of chlorophyll, cholic acid, aflatoxin B1 molecularly imprinted polymer (MIP) particles and cholic acid MIP nanofibers for application as selective solid phase extraction (SPE) sorbents. The particles were prepared by bulk polymerization and the nanofibers by a novel approach combining molecular imprinting and electrospinning technology. The AFB1 MIP particles were compared with an aflatoxin specific immunoextraction sorbent in cleaning-up and pre-concentrating aflatoxins from nut extracts. They both recorded high extraction efficiencies (EEs) of > 97 % in selectively extracting the aflatoxins (AFB1, AFB2, AFG1 and AFG2). High reproducibility marked by the low %RSDs of 0.6 to 99%) in the presence of planar pesticides than the currently employed graphitized carbon black (GCB) that removed both the chlorophyll (> 88%) and planar pesticides (> 89%). For the interfering cholic acid during drug residue analysis, cholic acid MIP electrospun nanofibers demonstrated to be more sensitive and possessing higher loading capacity than the MIP particles. 100% cholic acid was removed by the nanofibers from standard solutions relative to 80% by the particles. This showed that the nanofibers have better performance than the micro particles and as such have potential to replace the particle based SPE sorbents that are currently in use. All the templates were optimally removed from the prepared MIPs by employing a novel pressurized hot water extraction template removal method that was used for the first time in this thesis. The method employed only water, an environmentally friendly solvent to remove templates to ≥ 99.6% with template residual bleeding of ≤ 0.02%
An ion imprinted polymer for the selective extraction of mercury (II) ions in aqueous media
This thesis presents the application of an imprinted mercury(lI) polymer that we synthesized by copolymerizing the functional and cross-linking monomers, N'-[3-(Trimethoxysilyl)propyl] diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS) in the presence of mercury (II) ions as template. A bulk polymerization method following a double-imprinting procedure and employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer was employed in the synthesis. The imprinted polymer particles were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and their average size determined by screen analysis using standard test sieves. The relative selective coefficients (k') of the imprinted polymer evaluated from selective binding studies between Hg ²⁺and Cu²⁺ or Hg²⁺ and Cd²⁺, were 10588 and 3147, respectively. These values indicated highly favored Hg²⁺ extractions over the two competing ions. Application of the polymer to various real water samples (tap, sea, river, pulverized coal solution, treated and untreated sewerage from the vicinity of Grahamstown in South Africa) showed high extraction efficiencies (EEs) of Hg²⁺ ions; (over 84% in all cases) as evaluated from the detected unextracted Hg²⁺ ions by inductively coupled plasma optical emission spectroscopy (ICP-OES). The limit of detection (LOD, 3ơ) of the method was evaluated to be 0.036 ng ml⁻¹ and generally the data (n=10) had percentage relative standard deviation (%RSD) of less than 4%. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre-concentration of mercury(lI) ions in aqueous environments.KMBT_363Adobe Acrobat 9.54 Paper Capture Plug-i
An ion-imprinted polymer for the selective extraction of mercury(II) ions in aqueous media
A double-imprinted polymer exhibiting high sensitivity for mercury(II) in aqueous solution is presented. Polymer particles imprinted with mercury(II) were synthesised by copolymerising the functional and cross-linking monomers, N’–[3– (Trimethoxysilyl)–propyl]diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS). A double-imprinting procedure employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer, was adopted. The imprinted polymer was characterised by FTIR, scanning electron microscopy (SEM) and the average size determined by screen analysis using standard test sieves. Relative selective coefficients (k`) of the imprinted polymer evaluated from selective binding studies between Hg2+ and Cu2+ or Hg2+ and Cd2+ were 10 588 and 3 147, respectively. These values indicated highly-favoured Hg2+ extractions over the 2 competing ions. The results of spiked and real water samples showed high extraction efficiencies of Hg2+ ions, (over 84%) as evaluated from the detected unextracted Hg2+ ions by ICP-OES. The method exhibited a dynamic response concentration range for Hg2+ between 0.01 and 20 μg/mℓ, with a detection limit (LOD, 3σ) of 0.000036 μg/mℓ (36 ng/ℓ) that meets the monitoring requirements for the USA EPA of 2 000 ng/ℓ for Hg2+ in drinking water. Generally, the data (n=10) had percentage relative standard deviations (%RSD) of less than 4%. Satisfactory results were also obtained when the prepared sorbent was applied for the pre-concentration of Hg2+ from an aqueous certified reference material. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre–concentration of mercury(II) ions in aqueous environments
Optimal template removal from molecularly imprinted polymers by pressurized hot water extraction
An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat
Fabrication of innovative wound exudates dissolvable electrospun povidone-iodine loaded poly (Ɛ-caprolactone)-poly (ethylene oxide) composite nanofiber mat based wound bandages
Changing of bandage when nursing chronic wounds is a necessary exercise that encourages effective wound healing but often the bandage gets stuck to the wound, making changing it painful and uncomfortable. Furthermore, most of the wound medicine that is usually smeared on the bandage gets thrown away with the removed bandage unused. To deal with these challenges, we fabricated an innovative, dissolvable, drug releasing bandage based on electrospun povidone iodine (pvpi) blended poly (Ɛ-caprolactone), PCL-poly (ethylene oxide), PEO, composite nanofiber mats. From the experiments, smooth, yellow coloured nanofiber mats of calculated average fiber diameters of 341 nm were obtained from electrospinning an optimized 80:20 (v/v) PCL: PEO composite solution, blended with an optimized quantity of pvpi acting as model medicine incorporated in the structure of the nanofiber mats. From the performance evaluation results, the electrospun composite nanofiber mats excelled in releasing over 50% of the loaded pvpi over prolonged drug release time of 210 min which compared well with 200 min we reported in our previous work. Additionally, the composite nanofiber mats proved to be hydrophilic, influenced by the incorporation of the hydrophilic pvpi and PEO within the composite mats. Furthermore, the nanofiber mats gradually dissolved in phosphate-buffered saline (PBS), that was employed as wound exudate mimic, just under 24 h qualifying them as wound exudates-dissolvable nanofiber bandages that could revolutionize the bandage history and make wound care management free from bandage changes as well as totally removing medicine wastage during bandage changing and improving medicine efficacy during wound dressing.
Keywords: Chronic wounds, Wound exudates, Electrospinning, Polymer composite nanofibers, Electrospun nanofiber bandages, Innovative drug delivery bandages, Dissolvable nanostructured bandage