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2020 Volume 37 Issue 3
2020, 37(3): 245-255
doi: 10.11944/j.issn.1000-0518.2020.03.190350
Abstract:
Rare earth elements are a series of 17 elements including scandium, yttrium and lanthanide. They not only have physical and chemical similarities in nature, but also have their own unique and diverse electronic structures. From the chemical level, the characteristics of rare earth ions determine the nature of high-tech applications, such as rare earth permanent magnet, magnetic cooling, superconductivity, pyroelectricity, optical refrigeration, nonlinear optics, catalysis, etc. Rare earth functional materials are the basis for the application of these technologies. In terms of the requirements of scientific and technological development, the research and development of rare earth functional materials is the most important way to achieve high-quality development of rare earth resources. In this paper, based on the characteristics of rare earth ions, the orbital hybrid model is used to construct the basic relationship between rare earth ions and rare earth functional materials. The research progress of rare earth ions in composition design and performance optimization of rare earth functional materials in different application fields in recent years is summarized.
Rare earth elements are a series of 17 elements including scandium, yttrium and lanthanide. They not only have physical and chemical similarities in nature, but also have their own unique and diverse electronic structures. From the chemical level, the characteristics of rare earth ions determine the nature of high-tech applications, such as rare earth permanent magnet, magnetic cooling, superconductivity, pyroelectricity, optical refrigeration, nonlinear optics, catalysis, etc. Rare earth functional materials are the basis for the application of these technologies. In terms of the requirements of scientific and technological development, the research and development of rare earth functional materials is the most important way to achieve high-quality development of rare earth resources. In this paper, based on the characteristics of rare earth ions, the orbital hybrid model is used to construct the basic relationship between rare earth ions and rare earth functional materials. The research progress of rare earth ions in composition design and performance optimization of rare earth functional materials in different application fields in recent years is summarized.
2020, 37(3): 256-263
doi: 10.11944/j.issn.1000-0518.2020.03.190265
Abstract:
The photocatalytic reduction reactions can directly convert carbon dioxide (CO2) into hydrocarbon solar fuels utilizing the endless solar energy and semiconductor photocatalysts, which can solve the greenhouse effect, global warming, environmental pollution, and energy crisis, therefore it has become the ideal way nowadays. The mechanism of photocatalytic reduction of CO2 enhanced by oxygen vacancy and the photocatalytic systems with C1 and C2 components as reduction products were summarized in this paper. The first step in the CO2 photoreduction (i.e. the formation of CO2·- anionic radical by capturing an electron from the conduction band of a photocatalyst) was considered to be the rate-limiting step. The introduction of oxygen vacancy and induced coordinately unsaturated metal atoms sites could strengthen the electron capture from CO2 to CO2·-, thereby promoting the photocatalytic CO2 reduction. The existential problems in the process of photocatalytic reduction of CO2 enhanced by oxygen vacancy were explained objectively, and the development prospects were put forward.
The photocatalytic reduction reactions can directly convert carbon dioxide (CO2) into hydrocarbon solar fuels utilizing the endless solar energy and semiconductor photocatalysts, which can solve the greenhouse effect, global warming, environmental pollution, and energy crisis, therefore it has become the ideal way nowadays. The mechanism of photocatalytic reduction of CO2 enhanced by oxygen vacancy and the photocatalytic systems with C1 and C2 components as reduction products were summarized in this paper. The first step in the CO2 photoreduction (i.e. the formation of CO2·- anionic radical by capturing an electron from the conduction band of a photocatalyst) was considered to be the rate-limiting step. The introduction of oxygen vacancy and induced coordinately unsaturated metal atoms sites could strengthen the electron capture from CO2 to CO2·-, thereby promoting the photocatalytic CO2 reduction. The existential problems in the process of photocatalytic reduction of CO2 enhanced by oxygen vacancy were explained objectively, and the development prospects were put forward.
2020, 37(3): 264-270
doi: 10.11944/j.issn.1000-0518.2020.03.190271
Abstract:
Recently, efficient synthesis of porphyrin has become increasingly interesting in demand of many discoveries in metalloporphyrin complexes, especially for their excellent catalytic performances. Porphyrin is a conjugated macrocyclic compound composed of four pyrrole rings connected by methenylene. The state-of-the-art porphyrin synthesis includes propionic acid method and acetic acid/nitrobenzene method, but both suffer from low yield, high cost and heavy environmental pollution. In this work, an acetic acid/oxygen route for substituted porphyrin synthesis was developed, where the reaction temperature was kept at 120℃, while O2 was fed only in the first 30 min under reactant concentration of 0.24 mol/L, leading to tetra(4-bromophenyl) porphyrin in the yield of 53.8%. It should be noted that the acetic acid/oxygen route allows the concurrence of macrocyclic framework formation and oxidation, which provides a viable strategy for efficient porphyrin synthesis in convenient and less environment loading way.
Recently, efficient synthesis of porphyrin has become increasingly interesting in demand of many discoveries in metalloporphyrin complexes, especially for their excellent catalytic performances. Porphyrin is a conjugated macrocyclic compound composed of four pyrrole rings connected by methenylene. The state-of-the-art porphyrin synthesis includes propionic acid method and acetic acid/nitrobenzene method, but both suffer from low yield, high cost and heavy environmental pollution. In this work, an acetic acid/oxygen route for substituted porphyrin synthesis was developed, where the reaction temperature was kept at 120℃, while O2 was fed only in the first 30 min under reactant concentration of 0.24 mol/L, leading to tetra(4-bromophenyl) porphyrin in the yield of 53.8%. It should be noted that the acetic acid/oxygen route allows the concurrence of macrocyclic framework formation and oxidation, which provides a viable strategy for efficient porphyrin synthesis in convenient and less environment loading way.
2020, 37(3): 271-279
doi: 10.11944/j.issn.1000-0518.2020.03.190242
Abstract:
To screen environmental friendly new gemini surfactants, five carboxylate-type gemini surfactants EODPN1-EODPN 5[2, 2'-(1, 2-CH2CH2-di-O-)-di-(4-CnH2n+1COPhCOONa), n=5, 7, 9, 11 and 13] were synthesized from salicylic acid. The structures of the target products were confirmed by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectrometer. The properties of EODPN as surfactants were explored, and the relevant thermodynamic parameters were obtained by theoretical calculation using the Gibbs surface adsorption equation. The results show that EODPN has excellent surface activities, extremely low critical micelle concentration (CMC) values (minimum 0.4 mmol/L), good surface tension reduction performance (minimum 29.74 mN/m) and high surface adsorption per unit area Γ(up to 3.37×10-6 mol/m2). By changing the length of the hydrophobic alkyl carbon chain, the surface activity and self-assembly ability of EODPN were optimized, and EODPN4 was selected as the best surfactant. Based on EODPN4 which can be stably combined with copper ions, the detection of surfactant content is realized.
To screen environmental friendly new gemini surfactants, five carboxylate-type gemini surfactants EODPN1-EODPN 5[2, 2'-(1, 2-CH2CH2-di-O-)-di-(4-CnH2n+1COPhCOONa), n=5, 7, 9, 11 and 13] were synthesized from salicylic acid. The structures of the target products were confirmed by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectrometer. The properties of EODPN as surfactants were explored, and the relevant thermodynamic parameters were obtained by theoretical calculation using the Gibbs surface adsorption equation. The results show that EODPN has excellent surface activities, extremely low critical micelle concentration (CMC) values (minimum 0.4 mmol/L), good surface tension reduction performance (minimum 29.74 mN/m) and high surface adsorption per unit area Γ(up to 3.37×10-6 mol/m2). By changing the length of the hydrophobic alkyl carbon chain, the surface activity and self-assembly ability of EODPN were optimized, and EODPN4 was selected as the best surfactant. Based on EODPN4 which can be stably combined with copper ions, the detection of surfactant content is realized.
2020, 37(3): 293-300
doi: 10.11944/j.issn.1000-0518.2020.03.190283
Abstract:
Cellulose triacetate (CTA) is a kind of cellulose derivatives with high strength, and the modified CTA can be applied in the separation, adsorption and sensors, however, it is difficult to modify it by chemical initiated grafting. In this article, CTA membranes were successfully modified with poly(glycidyl methacrylate) (PGMA) by the combination of radiation-initiated grafting and the reversible addition-fragmentation chain transfer (RAFT) polymerization method. Effects of absorbed dose, concentration of GMA and amount of RAFT agent on degree of grafting were studied. The structure, morphology and surface property of the CTA membranes before and after grafting were investigated by Flourier transform infrared spectrometer (FT-IR), scanning electronic microscopy (SEM) and contact angle test. The results show that, for a higher degree of grafting and better morphology, the optimal conditions could be found at absorbed dose of 10~12 kGy, with mass fraction 30% of GMA and molar ratio 1/400 of RAFT agent and GMA. The grafted CTA membrane with the highest degree of grafting (41%) and the narrow distribution of relative molecular mass (1.33) can be obtained under suitable conditions. After grafting, the hydrophobicity of CTA membranes increases. The work provides a simple method to prepare grafted CTA with controlled structures. Compared with traditional radiation-initiated grafting, the radiation-initiated RAFT reaction conditions are easier to be controlled in RAFT-mediated grafting process, and the grafted polymer chains are better-distributed, which benefits further functionalization and practical application of modified CTA membranes.
Cellulose triacetate (CTA) is a kind of cellulose derivatives with high strength, and the modified CTA can be applied in the separation, adsorption and sensors, however, it is difficult to modify it by chemical initiated grafting. In this article, CTA membranes were successfully modified with poly(glycidyl methacrylate) (PGMA) by the combination of radiation-initiated grafting and the reversible addition-fragmentation chain transfer (RAFT) polymerization method. Effects of absorbed dose, concentration of GMA and amount of RAFT agent on degree of grafting were studied. The structure, morphology and surface property of the CTA membranes before and after grafting were investigated by Flourier transform infrared spectrometer (FT-IR), scanning electronic microscopy (SEM) and contact angle test. The results show that, for a higher degree of grafting and better morphology, the optimal conditions could be found at absorbed dose of 10~12 kGy, with mass fraction 30% of GMA and molar ratio 1/400 of RAFT agent and GMA. The grafted CTA membrane with the highest degree of grafting (41%) and the narrow distribution of relative molecular mass (1.33) can be obtained under suitable conditions. After grafting, the hydrophobicity of CTA membranes increases. The work provides a simple method to prepare grafted CTA with controlled structures. Compared with traditional radiation-initiated grafting, the radiation-initiated RAFT reaction conditions are easier to be controlled in RAFT-mediated grafting process, and the grafted polymer chains are better-distributed, which benefits further functionalization and practical application of modified CTA membranes.
2020, 37(3): 301-306
doi: 10.11944/j.issn.1000-0518.2020.03.190225
Abstract:
Magnesium hydroxide (Mg(OH) 2) was incorporated into cotton fiber to build surface roughness and improve flame-retardancy of cotton fabric. Subsequently, flame-retardant and superhydrophobic cotton fabric was prepared by further dip-coating of cotton fabric with polydimethylsiloxane (PDMS) solution. Fourier transform infrared spectrometer (FTIR) and scanning electronic microscopy (SEM) analysis confirmed that the pristine cotton fabrics is successfully modified by Mg(OH) 2 and PDMS. The hydrophobicity, thermal stability, flame retardant and durability of the treated cotton fibers were tested. The results indicated that Mg(OH) 2 is loaded on the fabric, which makes the surface of the pristine cotton to have a certain micro-nano structure and forms a rough coating. When the concentration of Mg(OH) 2 was 1.0 mol/L, Mg(OH) 2/PDMS coated fabric had contact angle (CA) of 158°, the limit oxygen index(LOI) of 24.5%, and the thermal conductivity of 0.0305 W/(m·K), suggesting excellent superhydrophobicity and flame-retardant performance. After 20 times of washing, 100 times of friction and under extreme processing conditions for coated fabric, its CA was greater than 150°, its LOI value was higher than 23%, revealing that the coated fabric has an excellent durability.
Magnesium hydroxide (Mg(OH) 2) was incorporated into cotton fiber to build surface roughness and improve flame-retardancy of cotton fabric. Subsequently, flame-retardant and superhydrophobic cotton fabric was prepared by further dip-coating of cotton fabric with polydimethylsiloxane (PDMS) solution. Fourier transform infrared spectrometer (FTIR) and scanning electronic microscopy (SEM) analysis confirmed that the pristine cotton fabrics is successfully modified by Mg(OH) 2 and PDMS. The hydrophobicity, thermal stability, flame retardant and durability of the treated cotton fibers were tested. The results indicated that Mg(OH) 2 is loaded on the fabric, which makes the surface of the pristine cotton to have a certain micro-nano structure and forms a rough coating. When the concentration of Mg(OH) 2 was 1.0 mol/L, Mg(OH) 2/PDMS coated fabric had contact angle (CA) of 158°, the limit oxygen index(LOI) of 24.5%, and the thermal conductivity of 0.0305 W/(m·K), suggesting excellent superhydrophobicity and flame-retardant performance. After 20 times of washing, 100 times of friction and under extreme processing conditions for coated fabric, its CA was greater than 150°, its LOI value was higher than 23%, revealing that the coated fabric has an excellent durability.
2020, 37(3): 307-313
doi: 10.11944/j.issn.1000-0518.2020.03.190233
Abstract:
Poly(oxy-1, 2-ethanediyl) methylphosphonate(PEMP) as a good flame retardant has lots of benefits such as non-toxic, low smoke, high phosphorus content and better flame retardant effects. γ-Al2O3 is a good catalyst for the condensation of ethylene glycol (EG) and dimethyl phosphate (DMMP) to produce PEMP. However, since γ-Al2O3 is easy to absorb CO2 and water to reduce its catalytic activity, activation is needed before use. The activation temperature affects the catalytic activity of γ-Al2O3. In this paper, γ-Al2O3 was activated at different temperatures from 300, 400, 500, 600, 700 and 800℃. γ-Al2O3 crystal form was analyzed by X-ray difraction (XRD) and its specific surface area, pore diameter and pore volume were measured by Brunauer-Emmett-Teller (BET) method. The change of infrared absorption was analyzed by Fourier transfer infrared (FTIR). The relative contents of Brønsted acid and Lewis acid sites in γ-Al2O3 were determined by pyridine adsorption-FTIR. The purity and viscosity of PEMP catalyzed by γ-Al2O3 were compared, and the optimal activation temperature of γ-Al2O3 was found to be 400, 500 and 600℃. At this time, γ-Al2O3 is a typical γ-Al2O3 with large specific surface area and small pore diameter, and the obtained PEMP product has the highest purity.
Poly(oxy-1, 2-ethanediyl) methylphosphonate(PEMP) as a good flame retardant has lots of benefits such as non-toxic, low smoke, high phosphorus content and better flame retardant effects. γ-Al2O3 is a good catalyst for the condensation of ethylene glycol (EG) and dimethyl phosphate (DMMP) to produce PEMP. However, since γ-Al2O3 is easy to absorb CO2 and water to reduce its catalytic activity, activation is needed before use. The activation temperature affects the catalytic activity of γ-Al2O3. In this paper, γ-Al2O3 was activated at different temperatures from 300, 400, 500, 600, 700 and 800℃. γ-Al2O3 crystal form was analyzed by X-ray difraction (XRD) and its specific surface area, pore diameter and pore volume were measured by Brunauer-Emmett-Teller (BET) method. The change of infrared absorption was analyzed by Fourier transfer infrared (FTIR). The relative contents of Brønsted acid and Lewis acid sites in γ-Al2O3 were determined by pyridine adsorption-FTIR. The purity and viscosity of PEMP catalyzed by γ-Al2O3 were compared, and the optimal activation temperature of γ-Al2O3 was found to be 400, 500 and 600℃. At this time, γ-Al2O3 is a typical γ-Al2O3 with large specific surface area and small pore diameter, and the obtained PEMP product has the highest purity.
2020, 37(3): 314-321
doi: 10.11944/j.issn.1000-0518.2020.03.190278
Abstract:
Ethylene tar char sulfonic acid was prepared by crosslinking and sulfonating method with the heavy components of ethylene tar after distillation as the raw material. The structure and properties of the catalyst were characterized by Flourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA-DTG), and scanning electron microscopy (SEM). The results showed that the catalyst presented an amorphous graphite carbon structure and high acid content (4.20 mmol/g). The sulfonic acid functional group on the surface was the key active center. The catalyst was used for the dehydration of fructose into 5-hydroxymethylfurfural (5-HMF). At the reaction time of 140 min, temperatureat of 130℃, the catalyst dosage of 0.3 g, the solvent dosage of 8 mL and the additive dosage of 0.3 g, the conversion of fructose and the yield of 5-HMF were 96.2% and 52.1%, respectively. The purity of 5-HMF obtained by separation was 97.0%. The conversion of fructose and the yield of 5-HMF remained above 85.1% and 40.8% after the catalyst was recycled five times.
Ethylene tar char sulfonic acid was prepared by crosslinking and sulfonating method with the heavy components of ethylene tar after distillation as the raw material. The structure and properties of the catalyst were characterized by Flourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA-DTG), and scanning electron microscopy (SEM). The results showed that the catalyst presented an amorphous graphite carbon structure and high acid content (4.20 mmol/g). The sulfonic acid functional group on the surface was the key active center. The catalyst was used for the dehydration of fructose into 5-hydroxymethylfurfural (5-HMF). At the reaction time of 140 min, temperatureat of 130℃, the catalyst dosage of 0.3 g, the solvent dosage of 8 mL and the additive dosage of 0.3 g, the conversion of fructose and the yield of 5-HMF were 96.2% and 52.1%, respectively. The purity of 5-HMF obtained by separation was 97.0%. The conversion of fructose and the yield of 5-HMF remained above 85.1% and 40.8% after the catalyst was recycled five times.
2020, 37(3): 322-331
doi: 10.11944/j.issn.1000-0518.2020.03.190192
Abstract:
In this paper, Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption, X-ray diffraction (XRD) andtransmission electron microscopy (TEM) were used to characterize the activated carbon treated via microwave with KOH. The results show that the oxygen-containing groups on the surface of activated carbon increase greatly, and the number of micropores decrease significantly. The selective catalytic hydrogenation performances of p-tert-butyl-α-methyl cinnamaldehyde over Pt, Pd, Ru and Rh supported on activated carbon were investigated. The Pt/C catalyst shows excellent selective hydrogenation for C═O, while the Pd/C catalyst has good selectivity for hydrogenation of C═C. The product distribution of selective hydrogenation of p-tert-butyl-α-methylcinnamaldehyde catalyzed by Pd-Pt bimetallic catalyst was also studied. The results show that the selective hydrogenation of C═O is gradually increased with an increase of Pt content, while the selectivity of hydrogenation of C═C decreases gradually over the Pd-Pt bimetallic catalyst. An optimal catalytic performance is obtained over Pd-Pt bimetallic catalyst when m(Pd):m(Pt)=4:1.
In this paper, Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption, X-ray diffraction (XRD) andtransmission electron microscopy (TEM) were used to characterize the activated carbon treated via microwave with KOH. The results show that the oxygen-containing groups on the surface of activated carbon increase greatly, and the number of micropores decrease significantly. The selective catalytic hydrogenation performances of p-tert-butyl-α-methyl cinnamaldehyde over Pt, Pd, Ru and Rh supported on activated carbon were investigated. The Pt/C catalyst shows excellent selective hydrogenation for C═O, while the Pd/C catalyst has good selectivity for hydrogenation of C═C. The product distribution of selective hydrogenation of p-tert-butyl-α-methylcinnamaldehyde catalyzed by Pd-Pt bimetallic catalyst was also studied. The results show that the selective hydrogenation of C═O is gradually increased with an increase of Pt content, while the selectivity of hydrogenation of C═C decreases gradually over the Pd-Pt bimetallic catalyst. An optimal catalytic performance is obtained over Pd-Pt bimetallic catalyst when m(Pd):m(Pt)=4:1.
2020, 37(3): 332-339
doi: 10.11944/j.issn.1000-0518.2020.03.190286
Abstract:
The heterocyclic aromatic halide, 2-chloro-5-(3-chloro-2, 6-dimethoxyphenyl)-1, 3, 4-thiadiazole (L), was synthesized by Gattermann reaction from the aminothiadiazole derivative. Its structure was characterized by nuclear magnetic resonance spectroscopy (NMR) and high resolution mass spectrometry (HRMS). Probe L was used as a small molecule fluorescent probe to detect 2, 4, 6-trinitrophenol (TNP), and its fluorescence characteristics were systematically studied. Furthermore, combined with theoretical calculations, the possible quenching mechanism was explored. The results showed that the probe L had high seletivity, high sensitivity and strong anti-interference ability to TNP, and exhibited good fluorescence performance in a wide pH range. It has lower detection limit (4.2×10-7 mol/L) and can be used for the detection of TNP in actual water samples.
The heterocyclic aromatic halide, 2-chloro-5-(3-chloro-2, 6-dimethoxyphenyl)-1, 3, 4-thiadiazole (L), was synthesized by Gattermann reaction from the aminothiadiazole derivative. Its structure was characterized by nuclear magnetic resonance spectroscopy (NMR) and high resolution mass spectrometry (HRMS). Probe L was used as a small molecule fluorescent probe to detect 2, 4, 6-trinitrophenol (TNP), and its fluorescence characteristics were systematically studied. Furthermore, combined with theoretical calculations, the possible quenching mechanism was explored. The results showed that the probe L had high seletivity, high sensitivity and strong anti-interference ability to TNP, and exhibited good fluorescence performance in a wide pH range. It has lower detection limit (4.2×10-7 mol/L) and can be used for the detection of TNP in actual water samples.
2020, 37(3): 340-349
doi: 10.11944/j.issn.1000-0518.2020.03.190175
Abstract:
In order to improve photocatalytic activity and acid-resistant alkalinity of ZnO and expand the absorption range of light, nanosized ZnO particles doped with Gd3+ (Zn1-xGdxO2(x=0~0.1)) were synthesized by thermal decomposition of the coordinated precursor, in which ethylenediamine tetraacetic acid(H4EDTA) is the ligand. Effects of the doping amount of Gd3+ on the structure, phase, morphology, optical properties and photo-electrical behaviors of ZnO were studied by X-ray diffraction (XRD) spectrometry, ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS), Fourier transform infrared (FT-IR) spectroscopy, flurescence spectroscopy (FL), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), dynamic photoelectrical current curve (i-t), etc. XRD results show that when the amount of Gd3+ is below 3%, there is a single phase of ZnO with hexagonal wurtzite structure. With the increase of Gd3+ doping(>3%), a little bit of second phase of Gd2O3 shows up and the grain size of ZnO is reduced. From i-t results, Gd3+ doping amount of 1% exhibits the biggest current density of 10 mA/m2. With the increase of Gd3+ doping, the band structure of ZnO is changed, the value of conduction band (CB), valence band (VB) and band-gap value (Eg) of ZnO are all reduced. At the same time, photo-degradation results of methyl orange (MO) reveal that Gd3+ doping can enhance the photocatalytic activity of ZnO, and the suitable amount is 1%. The catalytic selectivity and acid-resistant alkalinity of ZnO and Gd-doped ZnO were also studied simply.
In order to improve photocatalytic activity and acid-resistant alkalinity of ZnO and expand the absorption range of light, nanosized ZnO particles doped with Gd3+ (Zn1-xGdxO2(x=0~0.1)) were synthesized by thermal decomposition of the coordinated precursor, in which ethylenediamine tetraacetic acid(H4EDTA) is the ligand. Effects of the doping amount of Gd3+ on the structure, phase, morphology, optical properties and photo-electrical behaviors of ZnO were studied by X-ray diffraction (XRD) spectrometry, ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS), Fourier transform infrared (FT-IR) spectroscopy, flurescence spectroscopy (FL), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), dynamic photoelectrical current curve (i-t), etc. XRD results show that when the amount of Gd3+ is below 3%, there is a single phase of ZnO with hexagonal wurtzite structure. With the increase of Gd3+ doping(>3%), a little bit of second phase of Gd2O3 shows up and the grain size of ZnO is reduced. From i-t results, Gd3+ doping amount of 1% exhibits the biggest current density of 10 mA/m2. With the increase of Gd3+ doping, the band structure of ZnO is changed, the value of conduction band (CB), valence band (VB) and band-gap value (Eg) of ZnO are all reduced. At the same time, photo-degradation results of methyl orange (MO) reveal that Gd3+ doping can enhance the photocatalytic activity of ZnO, and the suitable amount is 1%. The catalytic selectivity and acid-resistant alkalinity of ZnO and Gd-doped ZnO were also studied simply.
2020, 37(3): 350-358
doi: 10.11944/j.issn.1000-0518.2020.03.190256
Abstract:
Nitrogen and iron co-doped carbon nanoparticles (N/Fe-CNPs) were synthesized by one-pot solvothermal method using L-tartaric acid and citric acid monohydrate as mixed carbon sources with the addition of ferric chloride hexahydrate, and ethylenediamine as the nitrogen source and polymerization reagent. The as-prepared N/Fe-CNPs could catalyze 3, 3', 5, 5'-tetramethylbenzidine to produce the soluble blue product. Combined with glucose oxidase (GOx), a sensitive method for the detection of hydrogen peroxide and glucose was established. The concentration of hydrogen peroxide and glucose has a good linear relationship with the absorbance of the reaction system. The limit of detection was calculated to be 42.5 and 76.1 nmol/L for hydrogen peroxide and glucose, respectively.
Nitrogen and iron co-doped carbon nanoparticles (N/Fe-CNPs) were synthesized by one-pot solvothermal method using L-tartaric acid and citric acid monohydrate as mixed carbon sources with the addition of ferric chloride hexahydrate, and ethylenediamine as the nitrogen source and polymerization reagent. The as-prepared N/Fe-CNPs could catalyze 3, 3', 5, 5'-tetramethylbenzidine to produce the soluble blue product. Combined with glucose oxidase (GOx), a sensitive method for the detection of hydrogen peroxide and glucose was established. The concentration of hydrogen peroxide and glucose has a good linear relationship with the absorbance of the reaction system. The limit of detection was calculated to be 42.5 and 76.1 nmol/L for hydrogen peroxide and glucose, respectively.
2020, 37(3): 359-366
doi: 10.11944/j.issn.1000-0518.2020.03.190252
Abstract:
This paper presents a new method for chiral identification and analysis of propranolol. The method quoted the systematic evolution of ligands by exponential enrichment technique based on graphene oxide (GO-SELEX). The specific aptamer with high affinity to the cardiovascular drug propranolol was selected after ten rounds of optimization and screening. Then resonance Rayleigh scattering spectroscopy (RRS) was used to detect the specificity of the reaction system. The experiment results showed that S-propranolol and R-propranolol had utterly spectral differences. The RRS spectrum of S-propranolol combined with the specific aptamer was significantly enhanced, while the RRS spectrum of R-propranolol's was almost unchanged. Therefore, the chiral propranolol could be effectively recognized. Based on the investigation of the reaction system and experimental conditions, S-propranolol could be tested experimentally and R-propranolol in the racemate can be calculated. The linear range of S-propranolol was 5~275 nmol/L and the detection limit was 0.5 nmol/L. The method was applied to the determination of racemic tablets with satisfactory results. The RRS spectra of chiral targets system binded with specific aptamer could reveal chirality differences and the chiral recognition of chiral enantiomers can be carried out.
This paper presents a new method for chiral identification and analysis of propranolol. The method quoted the systematic evolution of ligands by exponential enrichment technique based on graphene oxide (GO-SELEX). The specific aptamer with high affinity to the cardiovascular drug propranolol was selected after ten rounds of optimization and screening. Then resonance Rayleigh scattering spectroscopy (RRS) was used to detect the specificity of the reaction system. The experiment results showed that S-propranolol and R-propranolol had utterly spectral differences. The RRS spectrum of S-propranolol combined with the specific aptamer was significantly enhanced, while the RRS spectrum of R-propranolol's was almost unchanged. Therefore, the chiral propranolol could be effectively recognized. Based on the investigation of the reaction system and experimental conditions, S-propranolol could be tested experimentally and R-propranolol in the racemate can be calculated. The linear range of S-propranolol was 5~275 nmol/L and the detection limit was 0.5 nmol/L. The method was applied to the determination of racemic tablets with satisfactory results. The RRS spectra of chiral targets system binded with specific aptamer could reveal chirality differences and the chiral recognition of chiral enantiomers can be carried out.
2020, 37(3): 280-292
doi: 10.11944/j.issn.1000-0518.2020.03.190253
Abstract:
Synthesis of side-chain amino acid-bearing polymers with controllable primary structures is still a long-term challenge in polymer chemistry compared to biomacromolecules (such as proteins and DNA) with completely precise microstructures. Here, we describe the synthesis of high trans-stereoregular (>99%) and high head-to-tail regioregularity (>99%) leucine-based homopolymers and block copolymers with relatively low polydispersities ranging from 1.3 to 1.6, using two designed monomers, namely (cyclooct-2-ene-1-carbonyl)-L-leucine methyl ester (1) and (cyclooct-2-ene-1-carbonyl)-L-leucine (2), via Grubbs 2nd catalyst at mild conditions. Importantly, the block copolymer of monomers1 and2 with molar ratio n(1):n(2)=50:50 is soluble in acetone to form reverse micelles with radius around 30 nm, which is composed of a hydrophilic core of poly(2) and a hydrophobic shell of poly(1). However, the random copolymers with the same proportion was partially insoluble in the solvent. These amino acid-bearing polymers with well-defined regio-/stereoregular structures provide the basis for relevant applications in biomimetic materials.
Synthesis of side-chain amino acid-bearing polymers with controllable primary structures is still a long-term challenge in polymer chemistry compared to biomacromolecules (such as proteins and DNA) with completely precise microstructures. Here, we describe the synthesis of high trans-stereoregular (>99%) and high head-to-tail regioregularity (>99%) leucine-based homopolymers and block copolymers with relatively low polydispersities ranging from 1.3 to 1.6, using two designed monomers, namely (cyclooct-2-ene-1-carbonyl)-L-leucine methyl ester (1) and (cyclooct-2-ene-1-carbonyl)-L-leucine (2), via Grubbs 2nd catalyst at mild conditions. Importantly, the block copolymer of monomers1 and2 with molar ratio n(1):n(2)=50:50 is soluble in acetone to form reverse micelles with radius around 30 nm, which is composed of a hydrophilic core of poly(2) and a hydrophobic shell of poly(1). However, the random copolymers with the same proportion was partially insoluble in the solvent. These amino acid-bearing polymers with well-defined regio-/stereoregular structures provide the basis for relevant applications in biomimetic materials.
