scholarly journals Fabrication of Diatomite/Silicalite-1 Composites and Their Property for VOCs Adsorption

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 551 ◽  
Author(s):  
Yutong Liu ◽  
Tao Tian

Adsorption technology is an effective method to remove volatile organic compounds (VOCs). In this work, we prepared hierarchical porous materials using modified diatomite (Dt) as a support and nano-sized silicalite-1 (S-1) seeds as inorganic fillers, which were applied to adsorb volatile organic compounds (VOCs). The characterization of the composites indicated that S-1 was successfully coated onto the surface of modified Dt, and the best surface area of the composites was 398.8 m2/g, nearly 40 times as large as Dt. The adsorption capacities of Dt/S-1 composites for three probe VOCs (ethyl acetate, acetone, and toluene) were rather superior to Dt, and the composites had preferential adsorption selectivity for ethyl acetate. Effects of seeded zeolite contents and hydrothermal conditions for the adsorption capacity of composites were discussed in this paper. The composite seeded with 5 wt% S-1 zeolite, which was subsequently synthesized by hydrothermal reaction at 100 °C for four days, showed the maximum adsorption capacity (1.31 mmol/g for ethyl acetate). The pseudo second-order model provided a perfect fit to adsorption kinetics, while the Langmuir model agreed the best with the adsorption isotherms. In addition, the composites had selective adsorption to ethyl acetate among these three probes VOCs. The regeneration experiments were also carried out, and the adsorption efficiency of the adsorbents was still up to 67% after five adsorption–desorption cycles. The hierarchical porous Dt/S-1 composites have an excellent VOC adsorption performance, satisfactory selectivity, and recycling ability.

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3284
Author(s):  
Zhen Li ◽  
Yonghong Li ◽  
Jiang Zhu

Straw is one of the largest agricultural biowastes and a potential alternative precursor of activated carbon. Activated carbon prepared from different types of straw have great differences in structure and adsorption performance. In order to explore the performance of different straw-based activated carbon in volatile organic compounds adsorption, five common straws were selected as potential source materials for the preparation of SAC. The straw-based activated carbons were prepared and characterized via a thermo-gravimetric analysis, scanning electron microscope and the Brunauer–Emmett–Teller method. Among the five straw-based activated carbons, millet straw-derived activated carbon exhibited superior properties in SBET, Smic and adsorption capacities of both toluene and ethyl acetate. Furthermore, the preparation process of millet straw activated carbon was optimized via response surface methodology, using carbonization temperature, carbonization time and impregnation ratio as variables and toluene adsorption capacity, ethyl acetate adsorption capacity and activated carbon yield as responses. The optimal preparation conditions include a carbonization temperature of 572 °C, carbonization time of 1.56 h and impregnation ratio (ZnCl2/PM, w/w) of 1.60, which was verified experimentally, resulting in millet straw activated carbon with a toluene adsorption capacity of 321.9 mg/g and ethyl acetate adsorption capacity of 240.4 mg/g. Meanwhile, the adsorption isothermals and regeneration performance of millet straw activated carbon prepared under the optimized conditions were evaluated. The descriptive ability of the isothermals via the Redlich–Peterson equation suggests a heterogeneous surface on millet straw activated carbon. Recyclability testing has shown that millet straw activated carbon maintained a stable adsorption capacity throughout the second to fifth cycles. The results of this work indicate that millet straw activated carbon may be a potential volatile organic compound adsorbent for industrial application.


2018 ◽  
Vol 63 (1) ◽  
pp. 170-178 ◽  
Author(s):  
László Kiss

In this article, the feasibility of the CuxS modified carbon microdisc electrode was examined by exposure to four different volatile organic compounds (2-propanol, acetic acid, ethyl acetate and n-butylamine) directly in their vapour phase using cyclic voltammetry and amperometry. The performance of the modified microdisc was compared with the bare carbon microdisc (30 μm in diameter) which was involved in a narrow-gap cell. By using both methods high current increase was observed for 2-propanol with the modified electrode and its sensitivity was sufficiently higher than with the bare electrode. The modified electrode showed lower current signals in case of acetic acid and n-butylamine. The latter formed a condensation layer at the interelectrode gap. Neither the bare nor the modified electrode was sensitive to ethyl acetate.


2019 ◽  
Vol 19 (11) ◽  
pp. 7315-7319 ◽  
Author(s):  
Yi-Xin Wang ◽  
Hong Tao ◽  
Min-Nan Chen ◽  
Ling-Shao ◽  
Guang-Feng Shang ◽  
...  

In this study, a new type of molecular sieve/polyacrylonitrile fiber (M-PAN) was prepared by electrospinning to adsorb atmospheric volatile organic compounds (VOCs). The suitable content of molecular sieve in nanocomposites was also determined for achieving maximum VOCs adsorption capacity. SEM, TEM and N2 adsorption/desorption analyzer were performed for characterization of the surface morphology, structural properties, surface area and pore size. A part of molecular sieve is exposed on the fiber surface where VOCs can be adsorbed efficiently in a short time. Acetone was used as a challenge pollutant to evaluate the adsorption of VOCs at different recycling times and types of electrospinning nanofibers. The adsorption capacity of 6M-PAN (60% weight of molecular sieve) nanofiber reached 58.2 μg g−1 and the reused nanofibers nearly had the same adsorption capacity as the newly prepared nanofibers after several times of recirculation.


Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 372 ◽  
Author(s):  
Lipei Fu ◽  
Jiahui Zhu ◽  
Weiqiu Huang ◽  
Jie Fang ◽  
Xianhang Sun ◽  
...  

Carbon-silica composites with nanoporous structures were synthesized for the adsorption of volatile organic compounds (VOCs), taking tetraethyl orthosilicate (TEOS) as the silicon source and activated carbon powder as the carbon source. The preparation conditions were as follows: the pH of the reaction system was 5.5, the hydrophobic modification time was 50 h, and the dosage of activated carbon was 2 wt%. Infrared spectrum analysis showed that the activated carbon was dispersed in the pores of aerogel to form the carbon-silica composites material. The static adsorption experiments, dynamic adsorption-desorption experiments, and regeneration experiments show that the prepared carbon-silica composites have microporous and mesoporous structures, the adsorption capacity for n-hexane is better than that of conventional hydrophobic silica gel, and the desorption performance is better than that of activated carbon. It still has a high retention rate of adsorption capacity after multiple adsorption-desorption cycles. The prepared carbon-silica composites material has good industrial application prospects in oil vapor recovery, providing a new alternative for solving organic waste gas pollution.


2017 ◽  
Vol 14 (4) ◽  
pp. 1235-1250 ◽  
Author(s):  
Elsa Dilla Dertyasasa ◽  
Woro Anindito Sri Tunjung

ABSTRACT: Previous studies have reported that a number of organic compounds are present in kaffir lime (Citrus hystrix DC.) leaf extracts. Further research is needed to purify these compounds and determine which are biologically active. The objective of this study is to identify the volatile organic compounds of kaffir lime leaf crude extracts and fractions and to study their bioactivity. Fractionation was performed by the double maceration method, using hexane as the second solvent. TLC was performed to analyze the qualitative separation, whereas the individual constituents were detected using GC-MS. Our results showed that chloroform and ethyl acetate crude extracts contained various volatile organic compounds such as fatty acids, fatty alcohols, prenol lipids, sterol lipids, terpenoids and long chain alkanes. Fractionation separated these compounds into non-hexane fractions, which contained less volatile compounds, and hexane fractions. The volatile compounds of non-hexane fractions were identified to be long chain alkanes, meanwhile the hexane fractions contained terpenoids, fatty acids, fatty alcohols, prenol lipids and sterol lipids. Palmitic acid and terpenoids, such as citronellyl propionate, nerolidol, citronella and caryophyllene oxide were found to be the most dominant bioactive compounds in chloroform and ethyl acetate crude extract and their hexane fractions, which were reported to possess cytotoxicity against cancer cells. Meanwhile in non-hexane fractions, long chain alkanes such as triacontane and hentriacontane were found to be the most dominant bioactive compound which also possessed cytotoxic effect. In conclusion, fractionation using the double maceration method yielded different volatile organic compounds composition with different biological activities. The crude extracts and fractions of kaffir lime leaves were potential to be developed as a traditional medicine for cancer treatment.


2011 ◽  
Vol 46 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Maurício Batista Fialho ◽  
Maria Heloisa Duarte de Moraes ◽  
Annelise Roberta Tremocoldi ◽  
Sérgio Florentino Pascholati

The objective of this work was to evaluate the potential of an artificial mixture of volatile organic compounds (VOCs), produced by Saccharomyces cerevisiae, to control Sclerotinia sclerotiorum in vitro and in bean seeds. The phytopathogenic fungus was exposed, in polystyrene plates, to an artificial atmosphere containing a mixture of six VOCs formed by alcohols (ethanol, 3-methyl-1-butanol, 2-methyl-1-butanol and phenylethyl alcohol) and esters (ethyl acetate and ethyl octanoate), in the proportions found in the atmosphere naturally produced by yeast. Bean seeds artificially contamined with the pathogen were fumigated with the mixture of VOCs in sealed glass flasks for four and seven days. In the in vitro assays, the compounds 2-methyl-1-butanol and 3-methyl-1-butanol were the most active against S. sclerotiorum, completely inhibiting its mycelial growth at 0.8 µL mL-1, followed by the ethyl acetate, at 1.2 µL mL-1. Bean seeds fumigated with the VOCs at 3.5 µL mL-1 showed a 75% reduction in S. sclerotiorum incidence after four days of fumigation. The VOCs produced by S. cerevisiae have potential to control the pathogen in stored seeds.


Langmuir ◽  
2007 ◽  
Vol 23 (13) ◽  
pp. 7299-7305 ◽  
Author(s):  
Carmelo Herdes ◽  
Anabela Valente ◽  
Zhi Lin ◽  
João Rocha ◽  
João A. P. Coutinho ◽  
...  

2019 ◽  
Vol 35 (5) ◽  
pp. 649-668 ◽  
Author(s):  
Wee Kong Pui ◽  
Rozita Yusoff ◽  
Mohamed Kheireddine Aroua

Abstract A number of control methods have been adopted for the removal of hazardous volatile organic compounds (VOCs) from gas streams, particularly adsorption processes which are considered more prominent in terms of feasibility, effectiveness as well as cost competence compared to other methods. In this study, most of the activated-carbon-based adsorbents are critically reviewed in terms of their advantages and limitations for VOC gas adsorption. The choice of adsorbent and process parameters depends mainly on the type of VOC used, its chemical and structural properties, in addition to the adsorbent’s characteristics. The review discusses in detail the application of fixed-bed adsorption systems. A computational simulation study using quantum-chemical conductor like screening model for real solvents is included in this review which determines the efficiency in describing and predicting the adsorption technique required for each process. This review offers a comprehensive discussion of the VOC adsorption techniques and their implementation for different applications.


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