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1.
Materials (Basel) ; 17(12)2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38930398

RESUMO

This study examines the pyrolysis of agricultural residues, namely, coconut shells, rice husks, and cattle manure, in a vertical fixed-bed reactor at varying temperatures from 300 to 800 degrees Celsius for biochar production. The research aimed to evaluate the potential of biochar as biofuels, adsorbents, and soil amendments. Proximate, ultimate, and elemental analyses were conducted to determine their composition and caloric values. Several analytical techniques were used in the physical and chemical characterization of the biochar (SEM, FTIR, BET). The results indicated that the highest SBET values were achieved under different conditions for each biochar: 89.58 m2/g for BC-CS-700, 202.39 m2/g for BC-RH-600, and 42.45 m2/g for BC-CD-800. Additionally, all three biochars exhibited the highest caloric values at 600 °C. The results showed that 600 °C is the general optimal temperature to produce biochar from an assortment of biomass materials, considering their use for a variety of purposes. BC-CS-800 had the highest elemental carbon content at 93%, accompanied by a relative decrease in oxygen content. The van Krevelen diagram of biochar products shows that biochars derived from coconut shells and rice husks are suitable for use as fuels. Furthermore, FTIR analysis revealed the presence of oxygen-containing functional groups on the biochar surface, enhancing their pollutant adsorption capabilities. This study provides valuable insights into the scalable and environmentally sustainable production of biochar, emphasizing its role in improving soil quality, increasing energy density, and supporting sustainable agricultural practices.

2.
Materials (Basel) ; 16(24)2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-38138673

RESUMO

Porous carbon materials have been widely used to remove pollutants from the liquid-phase streams. However, their limited pore properties could be a major problem. In this work, the effects of post-washing methods (i.e., water washing and acid washing) on the textural characteristics of the resulting biochar and activated carbon products from pineapple peel biomass were investigated in the carbonization and CO2 activation processes. The experiments were set at an elevated temperature (i.e., 800 °C) holding for 30 min. It was found that the enhancement in pore property reached about a 50% increase rate, increasing from 569.56 m2/g for the crude activated carbon to the maximal BET surface area of 843.09 m2/g for the resulting activated carbon by water washing. The resulting activated carbon materials featured the microporous structures but also were characteristic of the mesoporous solids. By contrast, the enhancement in the increase rate by about 150% was found in the resulting biochar products. However, there seemed to be no significant variations in pore property with post-washing methods. Using the energy dispersive X-ray spectroscopy (EDS) and the Fourier Transform infrared spectroscopy (FTIR) analyses, it showed some oxygen-containing functional groups or complexes, potentially posing the hydrophilic characters on the surface of the resulting carbon materials.

3.
Materials (Basel) ; 16(24)2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-38138813

RESUMO

To valorize livestock manure, the present study investigated the production of biochar from cow dung (CD) by microwave pyrolysis. The pore properties and chemical characteristics of CD and CD-based biochar products were found to correlate with the process parameters like microwave power (300-1000 W) and residence time (5-20 min). The findings indicated that CD is an excellent biomass based on the richness of lignocellulosic constituents from the results of proximate analysis and thermogravimetric analysis (TGA). Higher calorific values were obtained at mild microwave conditions, giving the maximal enhancement factor 139% in comparison with the calorific value of CD (18.97 MJ/kg). Also, it can be concluded that the biochar product obtained at 800 W for a holding time of 5 min had the maximal BET surface area of 127 m2/g and total pore volume of 0.104 cm3/g, which were microporous and mesoporous in the nitrogen adsorption-desorption adsorption analysis. On the other hand, the CD-based biochar contained oxygen-containing functional groups and inorganic minerals based on the spectroscopic analyses by Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS), thus featuring to be prone to hydrophilicity in aqueous solutions.

4.
Artigo em Inglês | MEDLINE | ID: mdl-37966639

RESUMO

Over the past two decades, the Taiwan government promulgated some regulatory measures and promotional actions on energy efficiency promotion and renewable energy development. In March 2022, the "Taiwan's Pathway to Net-Zero Emissions in 2050" was announced to respond to the Paris Agreement. In order to achieve the goal, the Climate Change Response Act (CCRA) was passed on February 15, 2023, requiring the de-carbonization measures and adaptation strategies. The main aim of this paper was to analyze the changes in GHG emissions and renewable energy supply by using the updated data from the official statistics in connection with the trends of environmental and energy sustainability since 2000. The findings showed that total installed capacity of renewable power (especially in solar power and wind power) showed an amazing increase over the past decade, leading to the inclined GHG emissions and thus supporting the environmental and energy sustainability toward a low-carbon society. Furthermore, this paper summarized the development history and main differences concerning the carbon neutrality policy and legislation in Japan and South Korea. For achieving the staged targets of GHG emissions by 2030 and 2050, this paper finally addressed the technological approaches for achieving carbon neutrality by 2050 in Taiwan, focusing on the transformation of energy and industry, and the policy implications by all levels of government.

5.
Materials (Basel) ; 16(19)2023 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-37834694

RESUMO

In this work, the Honduras Mahogany (Swietenia macropnylla King, SMK) seed husk was used as a novel biomass resource for producing activated carbon by physical activation. The texture characteristics and chemical characterization of resulting products were investigated in correlation with the process parameters. Based on the thermochemical properties of the SMK biomass, the process conditions were set to a rate of about 10 °C/min under nitrogen (N2) flow of 500 cm3/min heated to 500 °C, then switched to carbon dioxide (CO2) flow of 100 cm3/min in the specified activation conditions (i.e., temperature of 700-850 °C for holding times of 0-60 min). Our findings showed that the texture characteristics (i.e., surface area and pore volume) increased with an activation temperature increase from 700 to 800 °C for a holding time of 30 min but gradually decreased as the temperature increased thereafter. Similarly, the texture characteristics also indicated an increasing trend with the residence time extending from 0 min to 30 min but slightly decreased as the time was extended to 60 min. Therefore, the optimal activation conditions for producing SMK-based activated carbon should be set at 800 °C for a holding time of 30 min to obtain the maximal texture characteristics (i.e., BET surface area of 966 m2/g and total pore volume of 0.43 cm3/g). On the other hand, the chemical characteristics were analyzed by energy dispersive X-ray spectroscopy (EDS) and Fourier Transform infrared spectroscopy (FTIR), showing oxygen complexes contained on the hydrophilic surface of the resulting activated carbon.

6.
Toxics ; 11(9)2023 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-37755733

RESUMO

Bisphenol A (BPA) has been identified as one of the endocrine disruptors or endocrine disrupting chemicals (EDCs). Due to its massive production (over 700,000 tons per year) and the extensive use of BPA-based plastics (i.e., polycarbonate and epoxy resin) in Taiwan, it was thus included as a toxic substance by the Ministry of Environment. This work surveyed the updated information about the production of BPA and its environmental distribution in Taiwan over the past decade. Furthermore, the regulatory strategies and countermeasures for managing the environmental risks of BPA by the Taiwan government were summarized to show the cross-ministerial efforts under the relevant acts, including the Toxic and Concerned Chemical Substances Control Act (TCCSCA), the Food Sanitation Management Act (FSMA) and the Commodity Inspection Act (CIA). The findings showed that most monitoring data were far below the acceptable risks. However, people may pose an adverse threat to the aquatic environment and human health via ecological and food chains. In addition, some countermeasures were further recommended to echo the international actions on environmental endocrine disruptors in recent years.

7.
Materials (Basel) ; 15(16)2022 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-36013931

RESUMO

In this work, the oily sludge (OS) from a local waste oil recycling plant was reused as a precursor for producing porous magnetic carbon composites (CC) by pyrolysis, followed by carbon dioxide activation. Based on the thermogravimetric analysis (TGA) of the OS feedstock, the preparation experiments were performed at 800−900 °C. From the pore analysis of the CC products, it indicated an increasing trend, as the BET surface area greatly increased from about 1.0 to 44.30 m2/g. In addition, the enhancement effect on the pore properties can be consistently obtained from the acid-washed CC products because the existing and new pores were reformed due to the leaching-out of inorganic minerals. It showed an increase from 32.27 to 94.45 m2/g and 44.30 to 94.52 m2/g at 850 and 900 °C, respectively, showing their mesoporous features. These porous and iron-containing features were also observed by the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). In addition, the adsorption removal of total organic carbon (TOC) in the raw wastewater, by the CC product, showed its high performance (>80%).

8.
Materials (Basel) ; 15(13)2022 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-35806810

RESUMO

In this work, pineapple peel (PP) was reused as a precursor in biochar (BC) production at elevated temperatures (i.e., 500−900 °C) for residence times of 0−60 min. The findings showed that pyrolysis temperature and residence time played a vital role in pore development. As pyrolysis temperature increased from 800 to 900 °C for residence times of 20 and 60 min, the data on the Brunauer−Emmett−Teller (BET) surface area of the resulting biochar products significantly jumped from 11.98−32.34 to 119.43−133.40 m2/g. In addition, there was a significant increase in the BET surface area from 1.02 to 133.40 m2/g with the residence time of 0 to 20 min at 900 °C. From the data of the nitrogen adsorption−desorption isotherms and the pore size distribution, both micropores (pore diameters of <2.0 nm) and mesopores (pore diameters of 2.0−50.0 nm) are present in the PP-based biochar products. Due to its good fittings in the pseudo-second-order model and its hydrophilic nature, as seen in the Fourier transform infrared spectroscopy (FTIR), the resulting biochar could be a porous material to be used for the effective removal of cationic compounds (i.e., methylene blue (MB)) from liquid phases.

9.
Materials (Basel) ; 14(13)2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34279298

RESUMO

Growing concerns about the circular economy and sustainable waste management for civil applications of non-hazardous mineral industrial waste have increased in recent years. Therefore, this study presents a trend analysis of industrial waste generation and treatment during the years of 2010-2020, and focused on promotion policies and regulatory measures for mandatory renewable resources from industrial sources in Taiwan, including reclaimed asphalt pavement (RAP) material, water-quenched blast furnace slag, and ilmenite chlorination furnace slag. According to the official database of the online reported statistics during the period of 2010-2020, approximately three million metric tons per year of renewable resources were totally reused in civil engineering or related cement products, reflecting a balanced supply chain in the domestic market. Among these, water-quenched blast furnace slag accounted for about 90% (about 2.7 million metric tons) in Taiwan. Currently, the legislative framework of sustainable waste management in Taiwan is based on the Waste Management Act and the Resource Recycling Act, but there are some problems with them. In order to effectively reduce environmental loadings and conserve natural resources to mitigate climate change, some recommendations are addressed from different points of view.

10.
Waste Manag Res ; 39(5): 713-719, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33749391

RESUMO

With the mass production and consumption of single-use plastics and other plastic products, plastic waste management and its resulting microplastic pollution have become the most noteworthy environmental issues. The main objectives of this paper were to review the regulatory measures for plastic waste reduction and recycling, analyse the trend changes on the recycled amounts of regulated plastic containers and also address the discussions on the impacts of COVID-19 on the expected increase in plastic waste. In the past two decades, the central competent authority (i.e. Environmental Protection Administration (EPA)) in Taiwan has promulgated some regulations governing plastic waste reduction and recycling, especially plastic containers. Based on the official statistics, it showed that total certified amounts of regulated plastic containers have increased from 45,552 tonnes in 1998 to 194,133 tonnes in 2019. This shift was in line with circular economy policies by the Zero Waste Program and Resource Recycling and Reuse Plan launched by the Taiwan EPA during this period. On the other hand, the COVID-19 pandemic will impact on the regulatory policies for plastic waste management because the excess use of regulated plastic products will be temporarily permitted due to the epidemic prevention and control measures. Although the increased proportion of plastic waste in municipal solid waste (MSW) will be beneficial for the energy efficiencies of waste-to-power systems in MSW incineration plants, the recycling and reduction rates of regulated plastic containers or products could decline during the COVID-19 breakout.


Assuntos
COVID-19 , Gerenciamento de Resíduos , Humanos , Pandemias , Plásticos , Reciclagem , SARS-CoV-2 , Resíduos Sólidos , Taiwan
11.
Waste Manag Res ; 39(1_suppl): 27-33, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33666120

RESUMO

Medical waste management in Taiwan is a crucial issue due to its highly environmental and human health risks. The main objectives of this paper were to analyse the status of medical waste generation and treatment in recent years, and also address the discussions on the impacts of coronavirus disease 2019 (COVID-19) on its generation in the first half of 2020. It showed that the reported quantities have slightly increased from 35,747 metric tonnes (Mt) in 2016 to 40,407 Mt in 2019, showing an average increase by 4.17%. This rate of increase was consistent with the hospital services. When classified by the reported codes, the C-type waste (infectious waste) accounted for about 89% of the reported quantities, which indicated an annual increase by 4.14% during the same period. In addition, the medical waste treatment in 2019 was mainly dependent on the commissioned treatment (80.18%), followed by the recycling (18.53%) and the self-treatment (1.29%). Furthermore, the impact of COVID-19 on the medical waste generation in Taiwan was not significant in the first half of 2020 compared to the data during the years of 2016-2019. It was indicated that the consistent trend was observed at the daily confirmed COVID-19 cases in Taiwan during this period. Obviously, the reduction in the hospital medical services during the COVID-19 outbreak should be offset by the increase in medical waste generation from the medical services. In order to try to ensure safe and complete destruction of the COVID-19 virus, all the waste generated from the healthcare facilities should be treated in the incineration plants.


Assuntos
COVID-19 , Resíduos de Serviços de Saúde , Gerenciamento de Resíduos , Humanos , SARS-CoV-2 , Taiwan
12.
J Agromedicine ; 26(4): 404-410, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33131422

RESUMO

The agricultural industry has been identified as one of the most hazardous industries in developed countries. The main purpose of this paper was to conduct a comprehensive analysis of agricultural accidents (or injuries) in Taiwan during the period of 2009 to 2018. The occupational accident rates (per 1,000 farmers employed) in Taiwan's agricultural industry showed a decreasing trend over the past decade from 1,486 in 2009 to 1,053 in 2018. This trend could be attributed to the joint-cooperation efforts of the industrial, official, academic, and non-profit parties under the Occupational Safety and Health Act (OSHA) revised in 2013. Although the occupational accident, disability, and other injury rates in all non-agriculture industries were higher than those in the agricultural industry during this period, the fatality rates in the agricultural industry were higher than those in all industries. Finally, some inter-ministerial measures on occupational safety and health issues in the agricultural industry for preventing agricultural accidents or injuries were recommended in the paper.


Assuntos
Acidentes de Trabalho , Saúde Ocupacional , Agricultura , Fazendeiros , Humanos , Taiwan/epidemiologia
13.
Toxics ; 8(3)2020 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-32645852

RESUMO

In the past two decades, the waste electrical and electronic equipment (WEEE) management has become an important environmental issue internationally because it contained hazardous substances like heavy metals and brominated flame retardants. Moreover, some valuable substances were used in the electrical and electronic products, thus representing a circular industry for recycling of WEEE. Therefore, the Taiwan government formulated a legal WEEE recycling system since 1998 in response to the international trends of sustainable waste management and extended producer responsibility (EPR). This article adopted the national statistics in Taiwan regarding the online reporting amounts of collected WEEE since it has been officially designated as one of the mandatory recyclable wastes. Furthermore, the regulatory measures were addressed to update the status and subsidiary fee rates of WEEE recycling in Taiwan. In addition, this article also put emphasis on the regulations governing the toxic chemical substances contained in the WEEE. It showed that the average annual recycling amounts of home electronic appliances, information technology products and lighting in Taiwan during the 2017-2018 were around 117,000, 18,000 and 4500 metric tons, respectively. It was also indicated that the current WEEE recycling market in Taiwan has become saturated, reflecting the regulatory promulgation and promotional measures successfully. In response to the Stockholm Convention on persistent organic pollutants (POPs) and the Minamata Convention on Mercury, the Taiwan government declared some brominated flame retardants and heavy metals (i.e., mercury and cadmium) as a "toxic chemical substance" under the Toxic and Concerned Chemical Substance Control Act (TCCSCA), which shall be prohibited to use in the preparation of electrical and electronic equipment (EEE) since 1 January 2016. Through the central governing authority, local governments, and private recyclers in Taiwan, the successful WEEE recycling system not only reduce the pressure on sanitary disposal systems, but also prevent the chemical hazards from solid waste incineration systems. More significantly, the WEEE recycling in Taiwan echoed the United Nations (UN) Agenda 2030 for sustainable development goals.

14.
Rev Environ Health ; 34(1): 81-89, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30854833

RESUMO

Indoor air quality (IAQ) standards and guidelines for volatile organic compounds (VOCs) have been stipulated by various national and international agencies. The main purpose of this paper is to establish an overview of indoor VOCs regarding their impacts on human health. Herein, 13 VOCs were designated as indoor air pollutants (IAPs) in the IAQ standards and guidelines. They were further grouped into four types: nonchlorinated aromatic compounds, chlorinated aromatic compounds, chlorinated aliphatic compounds and aldehydes. For this purpose, the present study discusses the criteria for designating VOCs, and summarizes their main sources in indoor environments. Because the occupational exposure limit (OEL) in workplaces has often used as a preliminary basis for establishing acceptable health-based IAQ guidelines in buildings and residences, this paper thus reviews the OEL values, especially in the American Conference of Governmental Industrial Hygienists (ACGIH)-threshold limit value (TLV). In addition, this paper also reviews the information about the classification of carcinogenicity in human by the international agencies for these VOCs. It shows that human tissues, including kidney, liver, leukemia, nasal cavity, paranasal sinus, liver and bile duct, could be more involved in the development of cancers or tumors when people are exposed to these VOCs through inhalation route in buildings over a long period of time.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Poluição do Ar em Ambientes Fechados/efeitos adversos , Monitoramento Ambiental , Exposição Ocupacional , Compostos Orgânicos Voláteis/efeitos adversos , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/classificação , Poluição do Ar em Ambientes Fechados/análise , Humanos , Hidrocarbonetos Aromáticos/efeitos adversos , Hidrocarbonetos Aromáticos/análise , Compostos Orgânicos Voláteis/análise
15.
Toxics ; 7(1)2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30678215

RESUMO

In Taiwan and other countries, glyphosate has been used widely as a non-selective herbicide over 40 years in crop lands and non-crop lands. However, public concerns about its environmental and health risks have increased rapidly because the International Agency for Research on Cancer (IARC) reclassified it as Group 2A (probably carcinogenic to humans) in 2015. From the viewpoints of environmental quality, food security and human health, it is necessary to regulate the release of glyphosate into the environment due to its massive use. The purpose of this case study was to analyze the historical consumption of glyphosate in Taiwan and also summarize its current regulatory measures through multi-ministerial levels. It showed that the sales quantities of glyphosate in Taiwan can be grouped into three stages, which include a ramping period (1984⁻1992), a stable period (1992⁻2007), and a declining period (2007⁻2016). These variations can be correlated with the annual price, manufacturers' promotion and other non-selective herbicide competitors (i.e., paraquat and glufosinate), as well as the excellent action features of glyphosate. It should be noted that its sales quantities significantly increased from 3200 metric tons in 2015 to 4535 metric tons in 2016 mainly due to the official announcement of paraquat ban effective in February 2019. The core regulations for protecting food security and water quality from the use of glyphosate are based on its residual limits and standards under the authorization of the Food Sanitation Management Act (FSMA) and the Water Pollution Control Act (WPCA), respectively. More importantly, there are occasional reports of contamination by herbicides (including glyphosate) in drinking water sources. Unfortunately, glyphosate is not yet considered among chemical items when evaluating drinking water quality standards in Taiwan.

16.
Toxics ; 5(4)2017 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-29051455

RESUMO

Among the halogenated hydrocarbons, chloromethanes (i.e., methyl chloride, CH3Cl; methylene chloride, CH2Cl2; chloroform, CHCl3; and carbon tetrachloride, CCl4) play a vital role due to their extensive uses as solvents and chemical intermediates. This article aims to review their main chemical/physical properties and commercial/industrial uses, as well as the environment and health hazards posed by them and their toxic decomposition products. The environmental properties (including atmospheric lifetime, radiative efficiency, ozone depletion potential, global warming potential, photochemical ozone creation potential, and surface mixing ratio) of these chlorinated methanes are also reviewed. In addition, this paper further discusses their atmospheric fates and human health implications because they are apt to reside in the lower atmosphere when released into the environment. According to the atmospheric degradation mechanism, their toxic degradation products in the troposphere include hydrogen chloride (HCl), carbon monoxide (CO), chlorine (Cl2), formyl chloride (HCOCl), carbonyl chloride (COCl2), and hydrogen peroxide (H2O2). Among them, COCl2 (also called phosgene) is a powerful irritating gas, which is easily hydrolyzed or thermally decomposed to form hydrogen chloride.

17.
Waste Manag ; 66: 53-60, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28487174

RESUMO

In the study, the biogas digestate was evaluated as a potential feedstock for preparing biochars at a broad temperature range of 300-900°C. The physico-chemical and pore properties of the resulting biochars (denoted as SDBC, solid digestate biochar), including calorific value (higher heating value), surface area/pore volume/pore size distribution, true density, scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD), were studied. It was found that the higher heating values of the SDBC products were on a decreasing trend as pyrolysis temperature increased, but they indicated an increase in true density. The results are probably associated with the active pyrolysis of the lignocellulosic fragments and the calcination (or shrinkage) processes, thus resulting in the increased contents of aromatic carbon clusters and main mineral constituents remained. Based on the pore properties, pyrolysis temperature at around 800°C seemed to be the optimal condition for producing SDBC, where its Brunauer-Emmet-Teller (BET) surface area (>100m2/g) largely increased as compared to that of the digestate feedstock (<1m2/g). Furthermore, the main compositions of mineral ash in the resulting biochar could exist as phosphates, carbonates, or oxides of calcium and other alkali/alkaline earth elements. According to the data on EDS and XRD, more pores could be significantly generated under severe pyrolysis (>700°C) due to the high aromaticity via the thermal decomposition of lignocelluloses and the volatilization of inorganic minerals.


Assuntos
Biocombustíveis , Carvão Vegetal , Temperatura , Difração de Raios X
18.
Toxics ; 4(2)2016 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-29051413

RESUMO

Since the 1970s, hazardous air pollutants (HAPs), so-called air toxics, have been of great concern because they can cause serious human health effects and have adverse effects on the environment. More noticeably, some of them are known to be human carcinogens. The objective of this paper is to investigate the regulatory systems and human health effects of air toxics which have been designated by the Taiwan government under the Air Pollution Control Act. These toxic air pollutants include acutely toxic gas (i.e., ammonia, chlorine, fluorides, hydrochloric acid, hydrogen cyanide, hydrogen sulfide, nitric acid, phosphoric acid and sulfuric acid), gas containing heavy metals, and carcinogenic chemicals (including formaldehyde, vinyl chloride, asbestos and matter containing asbestos, dioxins and furans, volatile organic compounds, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls). In line with international concern about the carcinogenic risk and environmental persistence of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs) and heavy metals in recent years, the current status in monitoring and reducing the emissions of PCDDs/PCDFs from stationary sources was analyzed as a case study in the present study. Furthermore, the control strategies for reducing emissions of air toxics from stationary sources in Taiwan were also addressed.

19.
Bioresour Technol ; 184: 344-348, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25451779

RESUMO

The chlorella-based microalgal residue (AR) was tested as a novel precursor for preparing activated carbons. A combined carbonization-activation process with flowing N2 and CO2 gases was used to prepare the carbon materials at the activation temperatures of 800-1000 °C and the residence times of 0-30 min in this work. The elemental contents, pore properties and scanning electron microscopy (SEM) observations of the resulting activated carbons have been performed. The results showed that activation temperature may be the most important parameter for determining their pore properties. The maximal Brunauer-Emmett-Teller (BET) surface area and total pore volume of the resulting activated carbon, which was produced at the activation temperature of 950 °C with the residence time of 30 min, were 840 m(2)/g and 0.46 cm(3)/g, respectively. More interestingly, the resulting activated carbons have significant nitrogen contents of 3.6-9.6 wt%, which make them lower carbon contents (i.e., 54.6-68.4 wt%) than those of commercial activated carbons.


Assuntos
Carvão Vegetal/metabolismo , Chlorella/metabolismo , Microscopia Eletrônica de Varredura , Nitrogênio/química , Porosidade , Temperatura
20.
Materials (Basel) ; 6(8): 3361-3372, 2013 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28811439

RESUMO

In this work, a planetary ball milling was used to modify the surface properties of calcite-based material from waste oyster shell under the rotational speed of 200-600 rpm, grinding time of 5-180 min and sample mass of 1-10 g. The milling significantly changed the microstructural properties of the calcite-based minerals (i.e., surface area, pore volume, true density, and porosity). The surface characterization of the resulting powder should be macroporous and/or nonporous based on the nitrogen adsorption/desorption isotherms. Under the optimal conditions at the rotational speed of 400 rpm, grinding time of 30 min and sample mass of 5 g, the resulting calcite-based powder had larger specific surface area (i.e., 10.64 m²·g-¹) than the starting material (i.e., 4.05 m²·g-1). This finding was also consistent with the measurement of laser-diffraction (i.e., 9.7 vs. 15.0 µm of mean diameter). In addition, the results from the scanning electron microscope (SEM) observation indicated that surface roughness can be enhanced as particle size decreases as a result of particle-particle attrition. Thus, grinding the aquacultural bioresource by a high-energy ball milling can create the fine materials, which may be applied in the fields of inorganic minerals like aggregate and construction material.

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