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Article
Publication date: 11 June 2018

Yuming Guan, Jingbo Mu, Hongwei Che, Xiaoliang Zhang and Zhixiao Zhang

The purpose of this study is to design carbon electrode materials for high performance electric double-layer capacitors (EDLCs) with pores that are large enough and have suitable…

Abstract

Purpose

The purpose of this study is to design carbon electrode materials for high performance electric double-layer capacitors (EDLCs) with pores that are large enough and have suitable pore size distribution for the electrolyte to access completely to improve EDLCs’ electrochemical performance.

Design/methodology/approach

This study develop an improved traditional KOH activation method, and a series of micro-meso hierarchical porous carbons have been successfully prepared from phenol formaldehyde resin by combining polyethylene glycol (PEG) and conventional KOH activation.

Findings

As evidenced by N2 adsorption/desorption tests, the obtained samples present Types IV and I-IV hybrid shape isotherms compared with KOH-activated resin (typical of Type I). The sample AC2-7-1, which the addition quantity of PEG is 25 per cent PF (weight ration) activated at 700? For 1 h is considered as the optimum preparation condition. It exhibits the highest specific capacitance value of 240 F/g in 30 wt% KOH aqueous electrolytes because of its higher specific surface area (2085 m2/g), greater pore volume (1.08 cm3/g) and the maximum mesoporosity (43 per cent). In addition, the capacity decay of this material is only 3.1 per cent after 1000 cycles.

Originality/value

The materials that are rich in micropores and mesopores show great potential in EDLC capacitors, particularly for applications where high power output and good high-frequency capacitive performances are required.

Details

World Journal of Engineering, vol. 15 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 6 November 2017

Yingyu Zhao, Zhenbin Chen, Jie Li, Zhen Liu, Donglei Liu and Zhizong Li

The purpose of the paper is to separate and purify flavonoids existed in Lamiophlomis rotata (Benth.) Kudo. by macroporous adsorption resin (MAR) mixed-bed technology.

Abstract

Purpose

The purpose of the paper is to separate and purify flavonoids existed in Lamiophlomis rotata (Benth.) Kudo. by macroporous adsorption resin (MAR) mixed-bed technology.

Design/methodology/approach

The adsorption and desorption parameters were characterized by UV-VIS spectrophotometry. The optimal MAR mixed bed was screened based on the adsorption experiments; the experiment process was investigated by the order of single, two and three MAR mixed bed separately; and the adsorption performance, which was composed by the authority of 80 per cent adsorption ratios and 20 per cent desorption ratios, was adopted to screen MAR mixed bed for flavonoids. The adsorption dynamic investigated the order of reaction first, and then the adsorption mechanism was researched further. The adsorption thermodynamic investigated the adsorption isotherm first, and then the adsorption feature was analyzed.

Findings

This research found that MAR mixed bed of LS-840 + LSD301 with mass ratio of mLS840:mLSD301 = 3:2 was the optimized combination, and the optimal conditions of the adsorption were volume V = 50 mL, time t = 6.5 h, T = 40°C. The desorption conditions were ethanol content = 70 per cent, desorption time t = 3.0 h, T = 40°C. The adsorption dynamic experimental data fitted better to the pseudo-second-order, and the intra-particle-diffusion model was more suitable for expression of the adsorption mechanism in mesopores process, whereas the homogeneous particle-diffusion model was more suitable in microspores. The adsorption was a physical and multilayer adsorption, and the adsorption driving force was disappeared as it transferred to the fourth layer.

Practical implications

Find an efficient way to separate flavonoids that useful for human’s health, which can not only utilize of plant resources effectively, but also make outstanding contributions to medical industry. It has very high economic and social value.

Originality/value

This contribution provided a new way to separate flavonoids from Lamiophlomis rotata (Benth.) Kudo. Under the optimal conditions, the adsorption rate (F) of MAR mixed bed LS-840 + LSD301 to the flavonoids was 97.81 per cent, the desorption rate (D) was 90.02 per cent and the purity of flavonoids was dramatically increased about 2.08 fold of the crude extract from 28 to 58.4 per cent, and the recovery yield of flavonoids arrived at 91.6 per cent after a circle of adsorption/desorption operation.

Details

Pigment & Resin Technology, vol. 46 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 5 December 2016

David O. Obada, Muhammad Dauda, Fatai O. Anafi, Abdulkarim S. Ahmed and Olusegun A. Ajayi

A structural and textural characterization study has been performed to investigate the adherence of zeolite-based catalyst washcoated onto honey-comb-type cordierite monoliths…

Abstract

Purpose

A structural and textural characterization study has been performed to investigate the adherence of zeolite-based catalyst washcoated onto honey-comb-type cordierite monoliths. The supports were characterized by the scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) techniques.

Design/methodology/approach

SEM/EDS provided quantitative estimate of the washcoated monolith as the elemental composition of catalyst coating. The XRD pattern deduced that the zeolite-based catalysts were successfully mounted on the cordierite support, showing the characteristic peaks of zeolites (Zeolite Socony Mobil–5; ZSM-5) at Braggs angles of 7.88°, 8.76°, 23.04°, 23.88° and 24.36°, whereas the characteristic peak of cordierite is seen at a Braggs angle of 10.44°.

Findings

The BET results proved that a monolayer of zeolite may serve the need for surface area and porosity. This was evident in the increase of surface area of washcoated support as against the bare support. The obtained isotherms were of Type IV, illustrating the presence of mesopores. The adsorption and desorption isotherm branches coincided over the interval 0 < P/P0 < 0.50 and 0 < P/P0 < 0.45, showing N2 reversible adsorption for the two samples, respectively.

Originality/value

It was concluded that the composite materials which are ZSM-5 (Si/Al = 25) and precursors of the transition salts of copper, zinc and ceria powders were deposited on the catalyst supports, establishing the success of the coating procedure relative to the adherence of the catalyst compositions on the ceramic support.

Details

World Journal of Engineering, vol. 13 no. 6
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 2 May 2017

Zhiling Ma, Yanjun Qiao, Fei Xie, Xianling Wang and Jing Wang

The purpose of this paper is to evaluate the role of encapsulation temperature on the preparation of silica-encapsulated waterborne aluminium pigments.

Abstract

Purpose

The purpose of this paper is to evaluate the role of encapsulation temperature on the preparation of silica-encapsulated waterborne aluminium pigments.

Design/methodology/approach

The waterborne aluminium pigments were prepared with H2O2 as anchoring agent and siloxane used as precursors in pH = 9.0 medium at different temperatures. The anchorage and compactness of silicon which on aluminium surface were characterized by optical microscopy, scanning electron microscopy and N2 adsorption-desorption. The anticorrosion property was characterized by the volume of produced hydrogen as a function of time.

Findings

The effect of encapsulation temperature on anticorrosion property of aluminium pigments is reflected from the anchorage and the compactness of silica on aluminium surface. Furthermore, when encapsulation temperature is 45-50°C, the silica platelets uniformly anchored on the aluminium surface as a dense film, which show the best anticorrosion property. Lower and higher encapsulation temperatures cause the silica platelets to agglomerate rather than anchor on the aluminium surface, which is unfavourable for the anchorage and the formation of compact silica film. The use of product in waterborne coatings gives a higher glossiness than that of raw material.

Research limitations/implications

Only pH = 9.0 medium was explored, and the other pH medium could result in different optimum temperatures.

Practical implications

The investigation results provide theoretical basis for obtaining excellent waterborne aluminium pigments.

Originality/value

The method of investigating corrosion resistance mechanism of aluminium pigments based on anchorage and compactness is novel.

Article
Publication date: 17 August 2018

XuDong Wang, Zhenbin Chen, Jiapeng Long, Chenglong Duan and Xueyan Du

The purpose of this paper is to separate and purify flavonoids from glycyrrhiza by macroporous adsorption resin (MAR) mixed-bed technology.

Abstract

Purpose

The purpose of this paper is to separate and purify flavonoids from glycyrrhiza by macroporous adsorption resin (MAR) mixed-bed technology.

Design/methodology/approach

The adsorption performance of MAR and MAR mixed bed for flavonoids was studied using ultraviolet-visible spectrophotometry.

Findings

The research shows that the MAR mixed bed of LZ-50+LZ-59 with a mass ratio of LZ-50:LZ-59(m:m) = 1:1 was the optimized combination with the optimal conditions of adsorption (pH = 6, T = 45°C) and desorption (liquid ratio R = 70%, T = 50°C, pH = 8) obtained, relatively.

Originality/value

This paper provides a novel way to separate flavonoids from glycyrrhiza. Under the optimal conditions, the adsorption rate (F) of MAR mixed-bed LZ-50+LZ-59 to the flavonoids was 62.5 per cent/g, the desorption rate (D) was 89.23 per cent and the purity was achieved at 80 per cent.

Details

Pigment & Resin Technology, vol. 47 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 10 July 2018

Zhen Yang, Yun Lin, Xingsheng Gu and Xiaoyi Liang

The purpose of this paper is to study the electrochemical properties of electrode material on activated carbon double layer capacitors. It also tries to develop a prediction model…

Abstract

Purpose

The purpose of this paper is to study the electrochemical properties of electrode material on activated carbon double layer capacitors. It also tries to develop a prediction model to evaluate pore size value.

Design/methodology/approach

Back-propagation neural network (BPNN) prediction model is used to evaluate pore size value. Also, an improved heuristic approach genetic algorithm (HAGA) is used to search for the optimal relationship between process parameters and electrochemical properties.

Findings

A three-layer ANN is found to be optimum with the architecture of three and six neurons in the first and second hidden layer and one neuron in output layer. The simulation results show that the optimized design model based on HAGA can get the suitable process parameters.

Originality/value

HAGA BPNN is proved to be a practical and efficient way for acquiring information and providing optimal parameters about the activated carbon double layer capacitor electrode material.

Article
Publication date: 1 March 2021

Xiaoyan Zhang, Runtian Wang, Yingyu Zhao, Jun Zhang, Boyuan Zhang, Zhengcan Chen, Pu Liu, Zhenbin Chen, Chunli Liu and Xiaoming Li

This paper aims to evaluate the separation and purification characteristics of flavonoids from polygonum cuspidatum (PC) extracts by using macroporous adsorption resins (MAR…

Abstract

Purpose

This paper aims to evaluate the separation and purification characteristics of flavonoids from polygonum cuspidatum (PC) extracts by using macroporous adsorption resins (MAR) mixed bed to improve the utilization rate of flavonoids.

Design/methodology/approach

Taking the separation performance of flavonoids as an evaluation index, the best MAR were screened from 31 sorts of MAR and combined the best MAR to form a MAR mixed bed for adsorption and separation of flavonoids.

Findings

By studying the separation conditions that affect flavonoids, the results showed that resin LZ-72 has best separation and purification effect on flavonoids under the optimal adsorption and desorption conditions, the purity of the obtained flavonoid compound reaches 82.50%, 2.66 times of the initial extract, and the recovery rate reaches 89.70%. Theoretical research results have shown that the adsorption of flavonoids by MAR conforms to the pseudo-second-order kinetics and Freundlich models.

Practical implications

Because the flavonoids in PC have great medicinal value, the purpose of this work is to develop a method of separating and purifying flavonoids from PC, which will provide a certain foundation for the development of medicine.

Originality/value

This contribution provided a novel way to separate flavonoids from PC. Under the optimal conditions, the content of flavonoids in the product was increased 2.66-fold from 31.01% to 82.50%, and the recovery yield was 89.70%.

Details

Pigment & Resin Technology, vol. 50 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 2 March 2020

Yongfeng Liu, Yi Liu and Duolong Di

The purpose of this study is to focus on the preparation of macroporous adsorption resins (MARs) functionalized with carbazole and N-methylimidazole, and adsorption behaviors of…

Abstract

Purpose

The purpose of this study is to focus on the preparation of macroporous adsorption resins (MARs) functionalized with carbazole and N-methylimidazole, and adsorption behaviors of (–)-epigallocatechin gallate (EGCG) and caffeine (CAF) on the functionalized MARs.

Design/methodology/approach

Based on the Friedel–Crafts and amination reactions, novel MARs functionalized with carbazole and N-methylimidazole were synthesized and characterized by the BET method. Accordingly, adsorption behaviors and structure-activity relationships for EGCG and CAF were studied in detail.

Findings

The results showed that pseudosecond-order kinetic model was provided with a better correlation for the adsorption of EGCG and CAF onto L-1 and L-2, and pseudofirst-order kinetic model was the most suitable model to illustrate the adsorption process for EGCG and CAF on L-3. The result indicated that Langmuir, Freundlich, Temkin–Pyzhev and Dubinin–Radushkevich isotherms all could better illustrate the adsorption processes of EGCG and CAF on L-1, L-2 and L-3.

Practical implications

This study provides theoretical guidance and technical support for the efficient separation and purification of EGCG and CAF from waste tea leaves by MARs on a large scale. In addition, the results showed that this novel MARs would provide useful help and be used in large-scale production of active ingredients from natural products in the industry and other fields.

Originality/value

Adsorption kinetic models such as pseudofirst-order, pseudosecond-order and intra-particle diffusion kinetic models, and adsorption isotherm models such as Langmuir, Freundlich, Temkin–Pyzhev and Dubinin–Radushkevich isotherms models were adopted to illustrate the adsorption mechanisms of EGCG and CAF. The main driving forces for MARs with no functional groups were pore sieving effects, pp conjugation effects and hydrophobic interactions, and the other significant driving forces for MARs functionalized with carbazole and N-methylimidazole were electrostatic interactions, ion-dipole and hydrogen bonding interactions. This study might provide scientific references and useful help for large-scale separating and enriching active ingredients in natural products using the technology of MARs with special functional groups.

Details

Pigment & Resin Technology, vol. 49 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 6 March 2017

Zhiling Ma, Yanjun Qiao, Yajing Wen, Xianling Wang and Jing Wang

This paper aims to evaluate the effect of precursors on the anticorrosion property of silica encapsulated waterborne aluminium pigments (WBAPs).

Abstract

Purpose

This paper aims to evaluate the effect of precursors on the anticorrosion property of silica encapsulated waterborne aluminium pigments (WBAPs).

Design/methodology/approach

The silica encapsulated WBAPs were prepared using different siloxanes as precursors. The anchorage and compactness of silica films on aluminium flakes were characterized by optical microscopy, scanning electron microscopy and N2 adsorption-desorption. The anticorrosion property and glossiness of WBAPs were evaluated.

Findings

The effect of precursors on anticorrosion property of silica encapsulated WBAPs is reflected from the anchorage and the compactness of silica on aluminium flakes surface. Furthermore, the structure of γ-aminopropyl triethoxysilane benefits the anchorage and the compatibility between pigment and acrylic resin. Neither high nor low ratio of tetraethoxysilane/γ-aminopropyl triethoxysilane is favourable to the anchorage and formation of dense silica film on the aluminium flakes surface. To obtain perfect WBAP, the precursors of silica must be carefully selected.

Research limitations/implications

Only four kinds of precursors were used in this work; other precursors could also be studied.

Practical implications

The investigation results provide theoretical basis to obtain excellent WBAPs.

Originality/value

The method to investigate anticorrosion property of WBAPs that is based on the effect of precursors on the performance of silica was novel.

Details

Pigment & Resin Technology, vol. 46 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 7 September 2015

Qiang Li, Jiahuan Du, Xugang Zhang, Chuanli Qin, Zheng Jin and Xuduo Bai

The purpose of this paper is to develop porous nitrogen-enriched carbon (NC-U) with high nitrogen concentration and high specific capacitance (Cpe) as the electrode material for…

Abstract

Purpose

The purpose of this paper is to develop porous nitrogen-enriched carbon (NC-U) with high nitrogen concentration and high specific capacitance (Cpe) as the electrode material for supercapacitors.

Design/methodology/approach

NC-U was obtained by carbonization of polyvinylpyrrolidone/melamine formaldehyde resin (PVP/MF) with different contents of urea. In comparison, NC-K was also prepared by the KOH activation method. A series of asymmetric supercapacitors with NC as a negative electrode was assembled. The composition, microstructure and electrochemical properties of NC and their supercapacitors were studied.

Findings

The results show that NC-U shows irregular particles with a porous honeycomb structure. High Cpe was obtained for urea-treated NC-U because of the improvement of nitrogen, conductivity and specific surface area (S BET ). NC-U50 with 13.15 per cent at nitrogen has the highest Cpe of 148.53 F/g because of the highest concentration of N-6 and N-5. NC-K with higher S BET has lower Cpe than NC-U50 because of its lower nitrogen concentration. When the specific power of the supercapacitor with NC-U50 as a negative electrode is 1,565.56 W/kg, its specific energy is still 4.35 Wh/kg. There is only 5.9 per cent decay in Cpe over 1,000 cycles.

Research limitations/implications

NC-U is a suitable electrode material for supercapacitors, which can be used in the field of electric vehicles to solve the problems of energy shortage and environmental pollutions.

Originality/value

Porous NC-U based on PVP/MF/urea composites with high nitrogen concentration and Cpe is novel, and it owns good electrochemical properties.

Details

Pigment & Resin Technology, vol. 44 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

1 – 10 of 27