Synthesis of indium phthalocyanines for photodynamic antimicrobial chemotherapy and photo-oxidation of pollutants
- Authors: Sindelo, Azole
- Date: 2019
- Subjects: Phthalocyanines , Azo dyes , Indium compounds , Photochemotherapy , Nanoparticles , Photodegradation , Pollutants , Water -- Purification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67581 , vital:29116
- Description: Indium (III) octacarboxyl phthalocyanine (ClInOCPc) alone and when conjugated to magnetic nanoparticles (MNP-ClInOCPc), 2(3),9(10),16(17),23(24)-octapyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOPyPc) and its quaternized derivative 2(3),9(10),16(17),23(24)-octamethylpyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOMePyPc) were synthesized. All Pcs were tested for both photodynamic antimicrobial chemotherapy (PACT) of an unknown water sample and photo-degradation of methyl red (MR). The singlet quantum yield (ΦΔ) for the ClInOCPc and MNP-ClInOCPc in PAN polymer fibers were 0.36 and 0.20 respectively using ADMA as a quencher in water. The photo-inactivation of bacteria in a water sample with unknown microbes was tested, with the MNP-ClInOCPc inactivating 90.6 % of the microbes and the ClInOCPc with 84.8 %. When embedded to the polymer, there was 48% bacterial clearance for ClInOCPc and 64% clearance for the MNP-ClInOCPc. The rate of degradation of MR increased with decrease of the MR concentration, with the MNP-ClInOCPc having the fastest rate. For ClInOPyPc and ClInOMePyPc, the singlet quantum yields were 0.46 and 0.33 in dimethylformamide (DMF), respectively. The PACT activity of ClInOMePyPc (containing 8 positive charges) was compared to those of 9(10),16(17),23(24)-tri-N-methyl-4-pyridylsulfanyl-2(3)-(4-aminophenoxy) phthalocyaninato chloro indium (III) triiodide (1) (containing 3 positive charges) and 2-[4-(N-methylpyridyloxy) phthalocyaninato] chloroindium (III) iodide (2) (containing 4 positive charges). When comparing ClInOMePyPc, 1 and 2, the largest log reduction for E. coli were obtained for complex 2 containing four positive charges hence showing it is not always the charge that determines the PACT activity, but the bridging atom in the phthalocyanine plays a role.
- Full Text:
- Date Issued: 2019
- Authors: Sindelo, Azole
- Date: 2019
- Subjects: Phthalocyanines , Azo dyes , Indium compounds , Photochemotherapy , Nanoparticles , Photodegradation , Pollutants , Water -- Purification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67581 , vital:29116
- Description: Indium (III) octacarboxyl phthalocyanine (ClInOCPc) alone and when conjugated to magnetic nanoparticles (MNP-ClInOCPc), 2(3),9(10),16(17),23(24)-octapyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOPyPc) and its quaternized derivative 2(3),9(10),16(17),23(24)-octamethylpyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOMePyPc) were synthesized. All Pcs were tested for both photodynamic antimicrobial chemotherapy (PACT) of an unknown water sample and photo-degradation of methyl red (MR). The singlet quantum yield (ΦΔ) for the ClInOCPc and MNP-ClInOCPc in PAN polymer fibers were 0.36 and 0.20 respectively using ADMA as a quencher in water. The photo-inactivation of bacteria in a water sample with unknown microbes was tested, with the MNP-ClInOCPc inactivating 90.6 % of the microbes and the ClInOCPc with 84.8 %. When embedded to the polymer, there was 48% bacterial clearance for ClInOCPc and 64% clearance for the MNP-ClInOCPc. The rate of degradation of MR increased with decrease of the MR concentration, with the MNP-ClInOCPc having the fastest rate. For ClInOPyPc and ClInOMePyPc, the singlet quantum yields were 0.46 and 0.33 in dimethylformamide (DMF), respectively. The PACT activity of ClInOMePyPc (containing 8 positive charges) was compared to those of 9(10),16(17),23(24)-tri-N-methyl-4-pyridylsulfanyl-2(3)-(4-aminophenoxy) phthalocyaninato chloro indium (III) triiodide (1) (containing 3 positive charges) and 2-[4-(N-methylpyridyloxy) phthalocyaninato] chloroindium (III) iodide (2) (containing 4 positive charges). When comparing ClInOMePyPc, 1 and 2, the largest log reduction for E. coli were obtained for complex 2 containing four positive charges hence showing it is not always the charge that determines the PACT activity, but the bridging atom in the phthalocyanine plays a role.
- Full Text:
- Date Issued: 2019
Characterization and application of phthalocyanine-gold nanoparticle conjugates
- Authors: Tombe, Sekai Lana
- Date: 2013
- Subjects: Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4293 , http://hdl.handle.net/10962/d1004517 , Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Description: This work presents the syntheses, photophysical and photochemical characterization of arylthio zinc phthalocyanines and their gold nanoparticle conjugates. Spectroscopic and microscopic studies confirmed the formation of the phthalocyanine-gold nanoparticle conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines. The studies showed that the presence of gold nanoparticles significantly lowered fluorescence quantum yields and lifetimes. However, this interaction did not restrict the formation of excited singlet and triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and therefore enhanced photocatalytic activity compared to the phthalocyanines. The zinc phthalocyanines and their gold nanoparticle conjugates were successfully incorporated into electrospun polymer fibers. Spectral characteristics of the functionalized electrospun fibers indicated that the phthalocyanines and phthalocyanine-gold nanoparticle conjugates were bound and their integrity was maintained within the polymeric fiber matrices. The photophysical and photochemical properties of the complexes were equally maintained within the electrospun fibers. The functionalized fibers were applied for the photoconversion of 4-chlorophenol and Orange G as model organic pollutants. , Microsoft� Word 2010 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Tombe, Sekai Lana
- Date: 2013
- Subjects: Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4293 , http://hdl.handle.net/10962/d1004517 , Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Description: This work presents the syntheses, photophysical and photochemical characterization of arylthio zinc phthalocyanines and their gold nanoparticle conjugates. Spectroscopic and microscopic studies confirmed the formation of the phthalocyanine-gold nanoparticle conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines. The studies showed that the presence of gold nanoparticles significantly lowered fluorescence quantum yields and lifetimes. However, this interaction did not restrict the formation of excited singlet and triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and therefore enhanced photocatalytic activity compared to the phthalocyanines. The zinc phthalocyanines and their gold nanoparticle conjugates were successfully incorporated into electrospun polymer fibers. Spectral characteristics of the functionalized electrospun fibers indicated that the phthalocyanines and phthalocyanine-gold nanoparticle conjugates were bound and their integrity was maintained within the polymeric fiber matrices. The photophysical and photochemical properties of the complexes were equally maintained within the electrospun fibers. The functionalized fibers were applied for the photoconversion of 4-chlorophenol and Orange G as model organic pollutants. , Microsoft� Word 2010 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Determining the willingness-to-pay for the removal of a local undesirable land use
- Authors: Cloete, Le Ann
- Date: 2012
- Subjects: Pollution , Willingness to pay -- South Africa -- Port Elizabeth , Pollutants
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:9010 , http://hdl.handle.net/10948/d1015979
- Description: A manganese ore dump and oil tank farm have been situated in the Port Elizabeth harbour for more than forty years. Although these facilities are independently operated and managed, they are viewed as one distinct disamenity, and there is strong local opposition to their continued location in the harbour. The negative environmental impacts (for example, water and air pollution) caused by the ore dump and tank farm have been well documented. This pollution takes the form of oil leaks from the oil tank farm, and ore dust pollution from the manganese ore dump. The air pollution caused by the manganese ore dump is a result of the dump currently being an open air handling and storage facility. The ore dust is dispersed into the air due to strong prevailing winds in the Bay and has resulted in respiratory illnesses of residents living in close proximity to the facility. Oil pollution, due to leakages experienced at the oil tank farm, has extended far beyond the periphery of the harbour. Inter alia, there has been a decline in local fish populations, as well as a decline in passive and active use satisfaction associated with the adjacent beach area, i.e. Kings Beach. These oil leakages, first reported in 2001, could have a detrimental effect on the Blue Flag status of this beach, as well as the Blue Flag status of other beaches situated further up the coast. The lease agreements for the oil tank farm and manganese ore dump are set to expire in 2014 and 2016, respectively. As yet, there is no consensus on when these disamenities will be (re)moved. In order to mitigate the secondary impacts of these facilities, both of them should be removed. Although these impacts should be the focus of public policy debates and cost-benefit assessments, no direct valuation method exists to value the economic cost to affected communities. Instead, non-market valuation methods, such as the contingent valuation method (CVM), are often applied to assign values to these economic costs. This study seeks to determine Nelson Mandela Bay households‟ preferences for the immediate removal of the manganese ore dump and oil tank farm from the Port Elizabeth harbour. This case was selected since it represents a current public policy debate issue that has not been resolved. Monetary estimates of people‟s preferences for the removal of pollution-creating activities can assist policy-makers and other stakeholders when locating industries in an urban setting. These estimates can also be of use in understanding the benefits associated with air and water quality improvement projects. The primary valuation technique used in this study is the CVM. This method was chosen as it is capable of measuring the economic significance of lost passive-use values of individuals affected by negative externalities. Both a non-parametric and a parametric estimate of mean willingness-to-pay (WTP) were derived. On average, a respondent was willing to pay a once-off amount of between R47.09 (non-parametric estimate) and R93.21 (parametric estimate). Non-parametric estimation (via the Turnbull estimator) was conducted to test the sensitivity of the parametric results (via a logit model). The logit model‟s results showed that the probability of a „yes‟ answer to the referendum question varies with a number of covariates in a realistic and expected way, which offers some support for the construct validity of this CV study. Household income, education, age, and disamenity awareness were significant determinants of individuals‟ responses to the WTP question. A summary of the findings of WTP estimates for both parametric and non-parametric analysis is provided in Table 1. Three primary recommendations stem from this study. Firstly, the study used a relatively small sample size. Although it was sufficient for a pilot study it is recommended that future research into this issue should aim for a much larger sample size to ensure more precise estimates of the WTP for the removal of the disamenity. Secondly, the conservative non-parametric mean WTP estimate should be used as opposed to the higher parametric mean WTP estimate. Third, the aggregate WTP estimation constitutes only a partial analysis of cost. A number of other factors and value streams need to be analysed and compared with the cost estimates generated by this study if adequate holistic decision-making is to take place with regard to the removal of the manganese ore dump and oil tank farm. More specifically, the total WTP estimated in this study should be viewed as only one input into a comprehensive social cost-benefit analysis to determine the desirability of the removal of this disamenity for wider society.
- Full Text:
- Date Issued: 2012
- Authors: Cloete, Le Ann
- Date: 2012
- Subjects: Pollution , Willingness to pay -- South Africa -- Port Elizabeth , Pollutants
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:9010 , http://hdl.handle.net/10948/d1015979
- Description: A manganese ore dump and oil tank farm have been situated in the Port Elizabeth harbour for more than forty years. Although these facilities are independently operated and managed, they are viewed as one distinct disamenity, and there is strong local opposition to their continued location in the harbour. The negative environmental impacts (for example, water and air pollution) caused by the ore dump and tank farm have been well documented. This pollution takes the form of oil leaks from the oil tank farm, and ore dust pollution from the manganese ore dump. The air pollution caused by the manganese ore dump is a result of the dump currently being an open air handling and storage facility. The ore dust is dispersed into the air due to strong prevailing winds in the Bay and has resulted in respiratory illnesses of residents living in close proximity to the facility. Oil pollution, due to leakages experienced at the oil tank farm, has extended far beyond the periphery of the harbour. Inter alia, there has been a decline in local fish populations, as well as a decline in passive and active use satisfaction associated with the adjacent beach area, i.e. Kings Beach. These oil leakages, first reported in 2001, could have a detrimental effect on the Blue Flag status of this beach, as well as the Blue Flag status of other beaches situated further up the coast. The lease agreements for the oil tank farm and manganese ore dump are set to expire in 2014 and 2016, respectively. As yet, there is no consensus on when these disamenities will be (re)moved. In order to mitigate the secondary impacts of these facilities, both of them should be removed. Although these impacts should be the focus of public policy debates and cost-benefit assessments, no direct valuation method exists to value the economic cost to affected communities. Instead, non-market valuation methods, such as the contingent valuation method (CVM), are often applied to assign values to these economic costs. This study seeks to determine Nelson Mandela Bay households‟ preferences for the immediate removal of the manganese ore dump and oil tank farm from the Port Elizabeth harbour. This case was selected since it represents a current public policy debate issue that has not been resolved. Monetary estimates of people‟s preferences for the removal of pollution-creating activities can assist policy-makers and other stakeholders when locating industries in an urban setting. These estimates can also be of use in understanding the benefits associated with air and water quality improvement projects. The primary valuation technique used in this study is the CVM. This method was chosen as it is capable of measuring the economic significance of lost passive-use values of individuals affected by negative externalities. Both a non-parametric and a parametric estimate of mean willingness-to-pay (WTP) were derived. On average, a respondent was willing to pay a once-off amount of between R47.09 (non-parametric estimate) and R93.21 (parametric estimate). Non-parametric estimation (via the Turnbull estimator) was conducted to test the sensitivity of the parametric results (via a logit model). The logit model‟s results showed that the probability of a „yes‟ answer to the referendum question varies with a number of covariates in a realistic and expected way, which offers some support for the construct validity of this CV study. Household income, education, age, and disamenity awareness were significant determinants of individuals‟ responses to the WTP question. A summary of the findings of WTP estimates for both parametric and non-parametric analysis is provided in Table 1. Three primary recommendations stem from this study. Firstly, the study used a relatively small sample size. Although it was sufficient for a pilot study it is recommended that future research into this issue should aim for a much larger sample size to ensure more precise estimates of the WTP for the removal of the disamenity. Secondly, the conservative non-parametric mean WTP estimate should be used as opposed to the higher parametric mean WTP estimate. Third, the aggregate WTP estimation constitutes only a partial analysis of cost. A number of other factors and value streams need to be analysed and compared with the cost estimates generated by this study if adequate holistic decision-making is to take place with regard to the removal of the manganese ore dump and oil tank farm. More specifically, the total WTP estimated in this study should be viewed as only one input into a comprehensive social cost-benefit analysis to determine the desirability of the removal of this disamenity for wider society.
- Full Text:
- Date Issued: 2012
Capillary membrane-immobilised polyphenol oxidase and the bioremediation of industrial phenolic effluent
- Authors: Edwards, Wade
- Date: 1999
- Subjects: Membranes (Technology) , Effluent quality , Pollutants , Phenols , Water -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4095 , http://hdl.handle.net/10962/d1008458
- Description: Waste-generating industrialisation is intrinsically associated with population and economic proliferation. This places considerable emphasis on South Africa's water shortage due to the integral relationship between population growth rate and infrastructure development. Of the various types of industry-generated effluents, those containing organic pollutants such as phenols are generally difficult to remediate. Much work has been reported in the literature on the use of enzymes for the removal of phenols from these waste-streams but little application of this bioremediation approach has reached practical fruition. This study focuses on integrating and synergistically combining the advantages of enzyme-mediated dephenolisation of synthetic and industrial effluent with that of membrane teclmology. The ability of the enzyme polyphenol oxidase to convert phenol and a number of its derivatives to chemically reactive o-quinones has been reported extensively in the literature. These o-quinones can then physically be removed from solution using various precipitation or adsorption techniques. The enzyme is, however, plagued by a product-induced phenomenon known as suicide inactivation, which renders it inactive and thus limits its application as a bioremediation tool. Integrating membrane technology with the enzyme's catalytic ability by immobilising polyphenol oxidase onto polysulphone and poly(ether sulphone) capillary membranes enabled the physical removal of these inhibitory products from the micro-environment of the immobilised enzyme which therefore increased the phenol conversion capability of the immobilised biocatalyst. Under non-immobilised conditions it was found that when exposed to a mixture of various phenols the substrate preference of the enzyme is a function of the R-group. Under immobilised conditions, however, the substrate preference of the enzyme becomes a function of certain transport constraints imposed by the capillary membrane itself. Furthermore, by integrating a quinone-removal process in the enzyme-immobilised bioreactor configuration, a 21-fold increase in the amount of substrate converted per Unit enzyme was observed when compared to the conversion capacity of the inunobilised enzyme without the product removal step. Comparisons were also made using different membrane bioreactor configurations (orientating the capillaries transverse as opposed to parallel to the module axis) and different immobilisation matrices (poly(ether sulphone) and polysulphone capillary membranes). Conversion efficiencies as high as 77% were maintained for several hours using the combination of transverse-flow modules and novel polysulphone capillary membranes. It was therefore concluded that immobilisation of polyphenol oxidase on capillary membranes does indeed show considerable potential for future development.
- Full Text:
- Date Issued: 1999
- Authors: Edwards, Wade
- Date: 1999
- Subjects: Membranes (Technology) , Effluent quality , Pollutants , Phenols , Water -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4095 , http://hdl.handle.net/10962/d1008458
- Description: Waste-generating industrialisation is intrinsically associated with population and economic proliferation. This places considerable emphasis on South Africa's water shortage due to the integral relationship between population growth rate and infrastructure development. Of the various types of industry-generated effluents, those containing organic pollutants such as phenols are generally difficult to remediate. Much work has been reported in the literature on the use of enzymes for the removal of phenols from these waste-streams but little application of this bioremediation approach has reached practical fruition. This study focuses on integrating and synergistically combining the advantages of enzyme-mediated dephenolisation of synthetic and industrial effluent with that of membrane teclmology. The ability of the enzyme polyphenol oxidase to convert phenol and a number of its derivatives to chemically reactive o-quinones has been reported extensively in the literature. These o-quinones can then physically be removed from solution using various precipitation or adsorption techniques. The enzyme is, however, plagued by a product-induced phenomenon known as suicide inactivation, which renders it inactive and thus limits its application as a bioremediation tool. Integrating membrane technology with the enzyme's catalytic ability by immobilising polyphenol oxidase onto polysulphone and poly(ether sulphone) capillary membranes enabled the physical removal of these inhibitory products from the micro-environment of the immobilised enzyme which therefore increased the phenol conversion capability of the immobilised biocatalyst. Under non-immobilised conditions it was found that when exposed to a mixture of various phenols the substrate preference of the enzyme is a function of the R-group. Under immobilised conditions, however, the substrate preference of the enzyme becomes a function of certain transport constraints imposed by the capillary membrane itself. Furthermore, by integrating a quinone-removal process in the enzyme-immobilised bioreactor configuration, a 21-fold increase in the amount of substrate converted per Unit enzyme was observed when compared to the conversion capacity of the inunobilised enzyme without the product removal step. Comparisons were also made using different membrane bioreactor configurations (orientating the capillaries transverse as opposed to parallel to the module axis) and different immobilisation matrices (poly(ether sulphone) and polysulphone capillary membranes). Conversion efficiencies as high as 77% were maintained for several hours using the combination of transverse-flow modules and novel polysulphone capillary membranes. It was therefore concluded that immobilisation of polyphenol oxidase on capillary membranes does indeed show considerable potential for future development.
- Full Text:
- Date Issued: 1999
The development of an immobilised-enzyme bioprobe for the detection of phenolic pollutants in water
- Authors: Russell, Ingrid Margaret
- Date: 1999
- Subjects: Pollutants -- Biodegradation , Pollutants , Chemical reactors , Membrane reactors , Fungi -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4069 , http://hdl.handle.net/10962/d1006211 , Pollutants -- Biodegradation , Pollutants , Chemical reactors , Membrane reactors , Fungi -- Biotechnology
- Description: The possibility of developing an immobilised-enzyme bioprobe, based on mushroom polyphenol oxidase, for the purely biological detection and quantification of phenolic pollutants in water was investigated. Polyphenol oxidase catalyses the bioconversion of many phenolic compounds into quinone-related coloured products. Thus, in an immobilised form, the enzyme serves as a visible indicator of the presence and concentration of phenolic pollutants in water. The objective of this research was to develop a portable, disposable bioprobe incorporating polyphenol oxidase for this purpose. The intensity of the colour changes produced by the enzyme on reaction with p-cresol, p-chlorophenol and phenol was found to increase proportionally with increasing concentrations of these substrates in solution. Immobilisation of the enzyme on various supports did not appear to significantly affect the catalytic activity of the enzyme. The enzyme was immobilised by adsorption and cross-linking on polyethersulphone, nitrocellulose and nylon membranes with the production of various colour ranges on reaction with the phenolic substrates. The most successful immobilisation of the enzyme, in terms of quantity and distribution of enzyme immobilised and colour production, was obtained with the enzyme immobilised by adsorption on nylon membranes in the presence of 3-methyl-2-benzothiazolinone hydrazone (MBTH). The enzyme, immobilised using this method, produced ranges of maroon colours in phenolic solutions and orange colours in cresylic solutions. The colour intensities produced were found to increase proportionally with increasing substrate concentration after 5 minutes exposure to the substrates. The bioprobe had a broad substrate specificity and was sensitive to substrate concentrations down to 0.05 mg/L. The enzyme activity of the bioprobe was not significantly affected in a pH range from 4 to 10 and in a temperature range from 5-25⁰C. The bioprobe activity was not affected by various concentrations of salt and metal ions and the bioprobe was able to detect and semi-quantify phenolic substrates in industrial effluent samples. These features of the bioprobe indicate that the commercialisation of such a bioprobe is feasible and this technology has been patented (Patent No. SA 97/0227). , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
- Authors: Russell, Ingrid Margaret
- Date: 1999
- Subjects: Pollutants -- Biodegradation , Pollutants , Chemical reactors , Membrane reactors , Fungi -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4069 , http://hdl.handle.net/10962/d1006211 , Pollutants -- Biodegradation , Pollutants , Chemical reactors , Membrane reactors , Fungi -- Biotechnology
- Description: The possibility of developing an immobilised-enzyme bioprobe, based on mushroom polyphenol oxidase, for the purely biological detection and quantification of phenolic pollutants in water was investigated. Polyphenol oxidase catalyses the bioconversion of many phenolic compounds into quinone-related coloured products. Thus, in an immobilised form, the enzyme serves as a visible indicator of the presence and concentration of phenolic pollutants in water. The objective of this research was to develop a portable, disposable bioprobe incorporating polyphenol oxidase for this purpose. The intensity of the colour changes produced by the enzyme on reaction with p-cresol, p-chlorophenol and phenol was found to increase proportionally with increasing concentrations of these substrates in solution. Immobilisation of the enzyme on various supports did not appear to significantly affect the catalytic activity of the enzyme. The enzyme was immobilised by adsorption and cross-linking on polyethersulphone, nitrocellulose and nylon membranes with the production of various colour ranges on reaction with the phenolic substrates. The most successful immobilisation of the enzyme, in terms of quantity and distribution of enzyme immobilised and colour production, was obtained with the enzyme immobilised by adsorption on nylon membranes in the presence of 3-methyl-2-benzothiazolinone hydrazone (MBTH). The enzyme, immobilised using this method, produced ranges of maroon colours in phenolic solutions and orange colours in cresylic solutions. The colour intensities produced were found to increase proportionally with increasing substrate concentration after 5 minutes exposure to the substrates. The bioprobe had a broad substrate specificity and was sensitive to substrate concentrations down to 0.05 mg/L. The enzyme activity of the bioprobe was not significantly affected in a pH range from 4 to 10 and in a temperature range from 5-25⁰C. The bioprobe activity was not affected by various concentrations of salt and metal ions and the bioprobe was able to detect and semi-quantify phenolic substrates in industrial effluent samples. These features of the bioprobe indicate that the commercialisation of such a bioprobe is feasible and this technology has been patented (Patent No. SA 97/0227). , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
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