Phthalocyanine-nanoparticle conjugates supported on inorganic nanofibers as photocatalysts for the treatment of biological and organic pollutants as well as for hydrogen generation
- Authors: Mapukata, Sivuyisiwe
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanofibers , Nanoparticles , Zinc , Hydrogen , Organic water pollutants , Water Purification , Electrospinning , Photocatalysis , Photodegradation , Anti-infective agents
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192831 , vital:45268 , 10.21504/10962/192831
- Description: This thesis reports on the synthesis, photophysicochemical and photocatalytic properties of various zinc phthalocyanines (Pcs). For enhanced properties and catalyst support, the reported Pcs were conjugated to different nanoparticles (NPs) through chemisorption as well as amide bond formation to yield Pc-NP conjugates. For increased catalyst surface area and catalyst reusability, the Pcs and some of their conjugates were also supported on electrospun inorganic nanofibers i.e. SiO2, hematite (abbreviated Hem and has formula α-Fe2O3), ZnO and TiO2 nanofibers. The effect that the number of charges on a Pc has on its antimicrobial activities was evaluated by comparing the photoactivities of neutral, octacationic and hexadecacationic Pcs against S. aureus, E. coli and C. albicans. The extent of enhancement of their antimicrobial activities upon conjugation (through chemisorption) to Ag NPs was also studied in solution and when supported on SiO2 nanofibers. The results showed that the hexadecacationic complex 3 possessed the best antimicrobial activity against all three microorganisms, in solution and when supported on the SiO2 nanofibers. Covalent conjugation of Pcs with carboxylic acid moieties (complexes 4-6) to amine functionalised NPs (Cys-Ag, NH2-Fe3O4 and Cys-Fe3O4@Ag) resulted in enhanced singlet oxygen generation and thus antibacterial efficiencies. Comparison of the photodegradation efficiencies of semiconductor nanofibers (hematite, ZnO and TiO2) when bare and when modified with a Pc (complex 6) were evaluated. Modification of the nanofibers with the Pc resulted in enhanced photoactivities for the nanofibers with the hematite nanofibers being the best. Modification of the hematite nanofibers with two different Pcs i.e. monosubstituted (complex 5) and an asymmetrical tetrasubstituted Pc (complex 6) showed that complex 6 better enhanced the activity of the nanofibers. Evaluation of the hydrogen generation efficiencies of the bare and modified TiO2 nanofibers calcined at different temperatures demonstrated that the anatase nanofibers calcined at 500 oC possessed the best catalytic efficiency. The efficiency of the TiO2 nanofibers was enhanced in the presence of the Co and Pd NPs as well as a Pc (complex 7), with the extent of enhancement being the greatest for the nanofibers modified with the Pd NPs. The reported findings therefore demonstrate the versatility of applications of Pcs for different water purification techniques when supported on different nanomaterials. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
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- Authors: Mapukata, Sivuyisiwe
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanofibers , Nanoparticles , Zinc , Hydrogen , Organic water pollutants , Water Purification , Electrospinning , Photocatalysis , Photodegradation , Anti-infective agents
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192831 , vital:45268 , 10.21504/10962/192831
- Description: This thesis reports on the synthesis, photophysicochemical and photocatalytic properties of various zinc phthalocyanines (Pcs). For enhanced properties and catalyst support, the reported Pcs were conjugated to different nanoparticles (NPs) through chemisorption as well as amide bond formation to yield Pc-NP conjugates. For increased catalyst surface area and catalyst reusability, the Pcs and some of their conjugates were also supported on electrospun inorganic nanofibers i.e. SiO2, hematite (abbreviated Hem and has formula α-Fe2O3), ZnO and TiO2 nanofibers. The effect that the number of charges on a Pc has on its antimicrobial activities was evaluated by comparing the photoactivities of neutral, octacationic and hexadecacationic Pcs against S. aureus, E. coli and C. albicans. The extent of enhancement of their antimicrobial activities upon conjugation (through chemisorption) to Ag NPs was also studied in solution and when supported on SiO2 nanofibers. The results showed that the hexadecacationic complex 3 possessed the best antimicrobial activity against all three microorganisms, in solution and when supported on the SiO2 nanofibers. Covalent conjugation of Pcs with carboxylic acid moieties (complexes 4-6) to amine functionalised NPs (Cys-Ag, NH2-Fe3O4 and Cys-Fe3O4@Ag) resulted in enhanced singlet oxygen generation and thus antibacterial efficiencies. Comparison of the photodegradation efficiencies of semiconductor nanofibers (hematite, ZnO and TiO2) when bare and when modified with a Pc (complex 6) were evaluated. Modification of the nanofibers with the Pc resulted in enhanced photoactivities for the nanofibers with the hematite nanofibers being the best. Modification of the hematite nanofibers with two different Pcs i.e. monosubstituted (complex 5) and an asymmetrical tetrasubstituted Pc (complex 6) showed that complex 6 better enhanced the activity of the nanofibers. Evaluation of the hydrogen generation efficiencies of the bare and modified TiO2 nanofibers calcined at different temperatures demonstrated that the anatase nanofibers calcined at 500 oC possessed the best catalytic efficiency. The efficiency of the TiO2 nanofibers was enhanced in the presence of the Co and Pd NPs as well as a Pc (complex 7), with the extent of enhancement being the greatest for the nanofibers modified with the Pd NPs. The reported findings therefore demonstrate the versatility of applications of Pcs for different water purification techniques when supported on different nanomaterials. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
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Photocatalysis of 4-chloro and 4-nonylphenols using novel symmetric phthalocyanines and asymmetric porphyrin supported on polyacrylonitrite nanofibres
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
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- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
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Phthalocyanine-nanoparticle conjugates for photodynamic therapy of cancer and phototransformation of organic pollutants
- Authors: Khoza, Phindile Brenda
- Date: 2015
- Subjects: Phthalocyanines , Nanoparticles , Photochemotherapy , Cancer -- Chemotherapy , Zinc oxide , Photocatalysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4538 , http://hdl.handle.net/10962/d1017918
- Description: The synthesis and extensive spectroscopical characterization of novel phthalocyanines are reported. The new compounds were characterized by elemental analysis, FT-IR, ¹HNMR, mass spectrometry and UV–Vis spectroscopy. The new phthalocyanines showed remarkable photophysicochemical behaviour. The novel phthalocyanines were then conjugated to nanoparticles, silver and ZnO. The coupling of the novel Pcs to nanoparticles was through covalent bonding and ligand exchange. These conjugates were supported onto electrospun polystyrene fibers and chitosan microbeads for use as photocatalysts. The efficiency of the immobilized Pcs and Pc-nanoparticles was assessed by the phototrasfromation of organic pollutants, methyl orange and Rhodamine 6G as model dyes. Upon conjugating phthalocyanines to nanoparticles, there was a great increase in the rate of photodegradation of the model dyes. The photodynamic activity of the novel phthalocyanines upon conjugating to nanoparticles and selected targeting agents is also reported. The targeting agents employed in this study are folic acid and polylysine. Conjugating the phthalocyanines to folic acid or polylysine improved the solubility of the phthalocyanines in aqueous media. The potency of the conjugates was investigated on breast (MCF-7), prostate and melanoma cancer cell lines. The phthalocyanines showed no toxicity in the absence of light. However, upon illumination, a concentration dependent cellular decrease was observed.
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- Authors: Khoza, Phindile Brenda
- Date: 2015
- Subjects: Phthalocyanines , Nanoparticles , Photochemotherapy , Cancer -- Chemotherapy , Zinc oxide , Photocatalysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4538 , http://hdl.handle.net/10962/d1017918
- Description: The synthesis and extensive spectroscopical characterization of novel phthalocyanines are reported. The new compounds were characterized by elemental analysis, FT-IR, ¹HNMR, mass spectrometry and UV–Vis spectroscopy. The new phthalocyanines showed remarkable photophysicochemical behaviour. The novel phthalocyanines were then conjugated to nanoparticles, silver and ZnO. The coupling of the novel Pcs to nanoparticles was through covalent bonding and ligand exchange. These conjugates were supported onto electrospun polystyrene fibers and chitosan microbeads for use as photocatalysts. The efficiency of the immobilized Pcs and Pc-nanoparticles was assessed by the phototrasfromation of organic pollutants, methyl orange and Rhodamine 6G as model dyes. Upon conjugating phthalocyanines to nanoparticles, there was a great increase in the rate of photodegradation of the model dyes. The photodynamic activity of the novel phthalocyanines upon conjugating to nanoparticles and selected targeting agents is also reported. The targeting agents employed in this study are folic acid and polylysine. Conjugating the phthalocyanines to folic acid or polylysine improved the solubility of the phthalocyanines in aqueous media. The potency of the conjugates was investigated on breast (MCF-7), prostate and melanoma cancer cell lines. The phthalocyanines showed no toxicity in the absence of light. However, upon illumination, a concentration dependent cellular decrease was observed.
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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
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- 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
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Removal and photocatalysis of 4-Nitrophenol using metallophthalocyanines
- Authors: Marais, Eloïse Ann
- Date: 2008
- Subjects: Photocatalysis , Catalysis , Electrochemistry , Nitrophenols , Phthalocyanines
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4343 , http://hdl.handle.net/10962/d1005005 , Photocatalysis , Catalysis , Electrochemistry , Nitrophenols , Phthalocyanines
- Description: Photodegradation of 4-nitrophenol (4-Np) in the presence of water-soluble zinc phthalocyanines and water-insoluble metallophthalocyanines is reported. The water-soluble phthalocyanines employed include zinc tetrasulphophthalocyanine (ZnPcS[subscript 4]), zinc octacarboxyphthalocyanine (ZnPc(COOH)[subscript 8]) and a sulphonated ZnPc containing a mixture of differently sulphonated derivatives (ZnPcS[subscript mix]), while the water-insoluble phthalocyanines used include unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring-substituted zinc tetranitro (ZnPc(NO[subscript 2])[subscript 4]), zinc tetraamino (ZnPc(NH[subscript 2])[subscript 4]), zinc hexadecafluoro (ZnPcF[subscript 16]) and zinc hexadecachloro (ZnPcCl[subscript 16]) phthalocyanines. The most effective water-soluble photocatalyst is ZnPcS[subscript mix] in terms of the high quantum yield obtained for 4-Np degradation (Φ[subscript 4-Np]) as well as its photostability. While ZnPc(COOH)[subscript 8] has the highest Φ[subscript 4-Np] value relative to the other water-soluble complexes, it degrades readily during photocatalysis. The Φ[subscript 4-Np] values were closely related to the singlet oxygen quantum yields Φ[subscript Δ] and hence aggregation. The rate constants for the reaction with 4-Np were kr = 0.67 x 10[superscript 6] mol[superscript -1] dm[superscript 3] s[superscript -1] for ZnPcS[subscript mix] and 7.7 x 10[superscript 6] mol[superscript -1] dm[superscript 3] s[superscript -1] for ZnPc(COOH)[subscript 8]. ClAlPc is the most effective photocatalyst relative to the other heterogeneous photocatalysts for the phototransformation of 4-Np, with 89 ± 8.4 % degradation of 4-Np achieved after 100 min. The least effective catalysts were ZnPcCl[subscript 16] and MgPc. The final products of the photocatalysis of 4-Np in the presence of the homogeneous photocatalysts include 4-nitrocatechol and hydroquinone, while degradation of 4-Np in the presence of the heterogeneous photocatalysts resulted in fumaric acid and 4-nitrocatechol. ClAlPc was employed for the heterogeneous photocatalysis of the non-systemic insecticide, methyl paraoxon. Complete degradation of the pesticide was confirmed by the disappearance of the HPLC trace for methyl paraoxon after 100 min of irradiation with visible light. The removal of 4-Np from an aqueous medium using commercially available Amberlite[superscript ®] IRA-900 modified with metal phthalocyanines was also investigated. The metallophthalocyanines immobilised onto the surface of Amberlite[superscript ®] IRA-900 include Fe (FePcS[subscript 4]), Co (CoPcS[subscript 4]) and Ni (NiPcS[subscript 4]) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcS[subscript mix]), Co (CoPcS[subscript mix]) and Ni (NiPcS[subscript mix]). Adsorption rates were fastest for the modified adsorbents at pH 9. Using the Langmuir-Hinshelwood kinetic model, the complexes showed the following order of 4-Np adsorption: CoPcS[subscript mix] > NiPcS[subscript 4] > NiPcS[subscript mix] > FePcS[subscript 4] > FePcS[subscript mix] > CoPcS[subscript 4]. The adsorbents were regenerated using dilute HNO[subscript 3], with 76 % (7.6 x 10[superscript -5] mol) of 4-Np recovered within 150 min.
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- Authors: Marais, Eloïse Ann
- Date: 2008
- Subjects: Photocatalysis , Catalysis , Electrochemistry , Nitrophenols , Phthalocyanines
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4343 , http://hdl.handle.net/10962/d1005005 , Photocatalysis , Catalysis , Electrochemistry , Nitrophenols , Phthalocyanines
- Description: Photodegradation of 4-nitrophenol (4-Np) in the presence of water-soluble zinc phthalocyanines and water-insoluble metallophthalocyanines is reported. The water-soluble phthalocyanines employed include zinc tetrasulphophthalocyanine (ZnPcS[subscript 4]), zinc octacarboxyphthalocyanine (ZnPc(COOH)[subscript 8]) and a sulphonated ZnPc containing a mixture of differently sulphonated derivatives (ZnPcS[subscript mix]), while the water-insoluble phthalocyanines used include unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring-substituted zinc tetranitro (ZnPc(NO[subscript 2])[subscript 4]), zinc tetraamino (ZnPc(NH[subscript 2])[subscript 4]), zinc hexadecafluoro (ZnPcF[subscript 16]) and zinc hexadecachloro (ZnPcCl[subscript 16]) phthalocyanines. The most effective water-soluble photocatalyst is ZnPcS[subscript mix] in terms of the high quantum yield obtained for 4-Np degradation (Φ[subscript 4-Np]) as well as its photostability. While ZnPc(COOH)[subscript 8] has the highest Φ[subscript 4-Np] value relative to the other water-soluble complexes, it degrades readily during photocatalysis. The Φ[subscript 4-Np] values were closely related to the singlet oxygen quantum yields Φ[subscript Δ] and hence aggregation. The rate constants for the reaction with 4-Np were kr = 0.67 x 10[superscript 6] mol[superscript -1] dm[superscript 3] s[superscript -1] for ZnPcS[subscript mix] and 7.7 x 10[superscript 6] mol[superscript -1] dm[superscript 3] s[superscript -1] for ZnPc(COOH)[subscript 8]. ClAlPc is the most effective photocatalyst relative to the other heterogeneous photocatalysts for the phototransformation of 4-Np, with 89 ± 8.4 % degradation of 4-Np achieved after 100 min. The least effective catalysts were ZnPcCl[subscript 16] and MgPc. The final products of the photocatalysis of 4-Np in the presence of the homogeneous photocatalysts include 4-nitrocatechol and hydroquinone, while degradation of 4-Np in the presence of the heterogeneous photocatalysts resulted in fumaric acid and 4-nitrocatechol. ClAlPc was employed for the heterogeneous photocatalysis of the non-systemic insecticide, methyl paraoxon. Complete degradation of the pesticide was confirmed by the disappearance of the HPLC trace for methyl paraoxon after 100 min of irradiation with visible light. The removal of 4-Np from an aqueous medium using commercially available Amberlite[superscript ®] IRA-900 modified with metal phthalocyanines was also investigated. The metallophthalocyanines immobilised onto the surface of Amberlite[superscript ®] IRA-900 include Fe (FePcS[subscript 4]), Co (CoPcS[subscript 4]) and Ni (NiPcS[subscript 4]) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcS[subscript mix]), Co (CoPcS[subscript mix]) and Ni (NiPcS[subscript mix]). Adsorption rates were fastest for the modified adsorbents at pH 9. Using the Langmuir-Hinshelwood kinetic model, the complexes showed the following order of 4-Np adsorption: CoPcS[subscript mix] > NiPcS[subscript 4] > NiPcS[subscript mix] > FePcS[subscript 4] > FePcS[subscript mix] > CoPcS[subscript 4]. The adsorbents were regenerated using dilute HNO[subscript 3], with 76 % (7.6 x 10[superscript -5] mol) of 4-Np recovered within 150 min.
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