Displaying publications 1 - 20 of 202 in total

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  1. Fulltext Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma
    Yaghoubi A, Mélinon P
    Sci Rep, 2013;3:1083.
    PMID: 23330064 DOI: 10.1038/srep01083
    In recent years, plasma-assisted synthesis has been extensively used in large scale production of functional nano- and micro-scale materials for numerous applications in optoelectronics, photonics, plasmonics, magnetism and drug delivery, however systematic formation of these minuscule structures has remained a challenge. Here we demonstrate a new method to closely manipulate mesostructures in terms of size, composition and morphology by controlling permeability at the boundaries of an impermeable plasma surrounded by a blanket of neutrals. In situ and rapid growth of thin films in the core region due to ion screening is among other benefits of our method. Similarly we can take advantage of exceptional properties of plasma to control the morphology of the as deposited nanostructures. Probing the plasma at boundaries by means of observing the nanostructures, further provides interesting insights into the behaviour of gas-insulated plasmas with possible implications on efficacy of viscous heating and non-magnetic confinement.
    Matched MeSH terms: Carbon/chemistry*
  2. Fulltext Ecofriendly adsorption and sensitive detection of Hg (II) by biomass-derived nitrogen-doped carbon dots: process modelling using central composite design
    Issa MA, Zentou H, Jabbar ZH, Abidin ZZ, Harun H, Halim NAA, et al.
    Environ Sci Pollut Res Int, 2022 Dec;29(57):86859-86872.
    PMID: 35802332 DOI: 10.1007/s11356-022-21844-0
    In this study, luminescent bio-adsorbent nitrogen-doped carbon dots (N-CDs) was produced and applied for the removal and detection of Hg (II) from aqueous media. N-CDs were synthesized from oil palm empty fruit bunch carboxymethylcellulose (CMC) and urea. According to several analytical techniques used, the obtained N-CDs display graphitic core with an average size of 4.2 nm, are enriched with active sites, stable over a wide range of pH and have great resistance to photobleaching. The N-CDs have bright blue emission with an improved quantum yield (QY) of up to 35.5%. The effect of the variables including pH, adsorbent mass, initial concentration and incubation time on the removal of Hg (II) was investigated using central composite design. The statistical results confirmed that the adsorption process could reach equilibrium within 30 min. The reduced cubic model (R2 = 0.9989) revealed a good correlation between the observed values and predicted data. The optimal variables were pH of 7, dose of 0.1 g, initial concentration of 100 mg/L and duration of 30 min. Under these conditions, adsorption efficiency of 84.6% was obtained. The adsorption kinetic data could be well expressed by pseudo-second-order kinetic and Langmuir isotherm models. The optimal adsorption capacity was 116.3 mg g-1. Furthermore, the adsorbent has a good selectivity towards Hg (II) with a detection limit of 0.01 μM due to the special interaction between Hg (II) and carboxyl/amino groups on the edge of N-CDs. This work provided an alternative direction for constructing low-cost adsorbents with effective sorption and sensing of Hg (II).
    Matched MeSH terms: Carbon/chemistry
  3. Rapid Surface Modification of Stainless Steel 304L Electrodes for Microbial Electrochemical Sensor Application
    Yeo RYZ, Chin BH, Hil Me MF, Chia JF, Pham HT, Othman AR, et al.
    ACS Biomater Sci Eng, 2023 Nov 13;9(11):6034-6044.
    PMID: 37846081 DOI: 10.1021/acsbiomaterials.3c00453
    Electrogenic microorganisms serve as important biocatalysts for microbial electrochemical sensors (MESes). The electrical signal produced is based on the rate of electron transfer between the microbes and electrodes, which represents the biotoxicity of water. However, existing MESes require complex and sophisticated fabrication methods. Here, several low-cost and rapid surface modification strategies (carbon powder-coated, flame-oxidized, and acid-bleached) have been demonstrated and studied for biosensing purposes. Surface-modified MESe bioanodes were successfully applied to detect multiple model pollutants including sodium acetate, ethanol, thinner, and palm oil mill effluent under three different testing sequences, namely, pollutant incremental, pollutant dumping, and water dilution tests. The carbon powder-coated bioanode showed the most responsive signal profile for all the three tests, which is in line with the average roughness values (Ra) when tested with atomic force microscopy. The carbon powder-coated electrode possessed a Ra value of 0.844, while flame-oxidized, acid-bleached, and control samples recorded 0.323, 0.336, and 0.264, respectively. The higher roughness was caused by the carbon coating and provided adhesive sites for microbial attachment and growth. The accuracy of MESe was also verified by correlating with chemical oxygen demand (COD) results. Similar to the sensitivity test, the carbon powder-coated bioanode obtained the highest R2 value of 0.9754 when correlated with COD results, indicating a high potential of replacing conventional water quality analysis methods. The reported work is of great significance to showcase facile surface modification techniques for MESes, which are cost-effective and sustainable while retaining the biocompatibility toward the microbial community with carbon-based coatings.
    Matched MeSH terms: Carbon/chemistry
  4. Aromatic biomass (torch ginger) leaf-derived three-dimensional honeycomb-like carbon to enhance gravimetric supercapacitor
    Taer E, Yanti N, Padang E, Apriwandi A, Zulkarnain Z, Haryanti NH, et al.
    J Sci Food Agric, 2023 Dec;103(15):7411-7423.
    PMID: 37431642 DOI: 10.1002/jsfa.12846
    BACKGROUND: Porous carbon electrode (PCE) is identified as a highly suitable electrode material for commercial application due to its production process, which is characterized by simplicity, cost-effectiveness and environmental friendliness. PCE was synthesized using torch ginger (Etlingera elatior (Jack) R.M. Smith) leaves as the base material. The leaves were treated with different concentrations of ZnCl2 , resulting in a supercapacitor cell electrode with unique honeycomb-like three-dimensional (3D) morphological pore structure. This PCE comprises nanofibers from lignin content and volatile compounds from aromatic biomass waste.

    RESULTS: From the characterization of physical properties, PCE-0.3 had an impressive amorphous porosity, wettability and 3D honeycomb-like structural morphology with a pore framework consisting of micropores and mesopores. According to the structural advantages of 3D hierarchical pores such as interconnected honeycombs, PCE-0.3 as supercapacitor electrode had a high specific capacitance of up to 285.89 F g-1 at 1 A. Furthermore, the supercapacitor exhibited high energy and power density of 21.54 Wh kg-1 and 161.13 W kg-1 , respectively, with a low internal resistance of 0.059 Ω.

    CONCLUSION: The results indicated that 3D porous carbon materials such as interconnected honeycombs derived from the aromatic biomass of torch ginger leaves have significant potential for the development of sustainable energy storage devices. © 2023 Society of Chemical Industry.

    Matched MeSH terms: Carbon/chemistry
  5. Fulltext Microwave conductivity of sorted CNT assemblies
    Bulmer JS, Martens J, Kurzepa L, Gizewski T, Egilmez M, Blamire MG, et al.
    Sci Rep, 2014 Jan 21;4:3762.
    PMID: 24446019 DOI: 10.1038/srep03762
    Recent progress with tailored growth and post-process sorting enables carbon nanotube (CNT) assemblies with predominantly metallic or semi-conducting concentrations. Cryogenic and microwave measurements performed here show transport dimensionality and overall order increasing with increasing metallic concentration, even in atmospheric doping conditions. By 120 GHz, the conductivity of predominantly semi-conducting assemblies grew to 400% its DC value at an increasing growth rate, while other concentrations a growth rate that tapered off. A generalized Drude model fits to the different frequency dependent behaviors and yields useful quality control parameters such as plasma frequency, mean free path, and degree of localization. As one of the first demonstrations of waveguides fabricated from this material, sorted CNTs from both as-made and post-process sources were inserted into sections of practical micro-strip. With both sources, sorted CNT micro-strip increasingly outperformed the unsorted with increasing frequency-- illustrating that sorted CNT assemblies will be important for high frequency applications.
    Matched MeSH terms: Nanotubes, Carbon/chemistry*
  6. Contributions of humic substances to the dissolved organic carbon pool in wetlands from different climates
    Watanabe A, Moroi K, Sato H, Tsutsuki K, Maie N, Melling L, et al.
    Chemosphere, 2012 Aug;88(10):1265-8.
    PMID: 22564456 DOI: 10.1016/j.chemosphere.2012.04.005
    Wetlands are an important source of DOM. However, the quantity and quality of wetlands' DOM from various climatic regions have not been studied comprehensively. The relationship between the concentrations of DOM (DOC), humic substances (HS) and non-humic substances (NHS) in wetland associated sloughs, streams and rivers, in cool temperate (Hokkaido, Japan), sub-tropical (Florida, USA), and tropical (Sarawak, Malaysia) regions was investigated. The DOC ranged from 1.0 to 15.6 mg CL(-1) in Hokkaido, 6.0-24.4 mg CL(-1) in Florida, and 18.9-75.3 mg CL(-1) in Sarawak, respectively. The relationship between DOC and HS concentrations for the whole sample set was regressed to a primary function with y-intercept of zero (P<0.005) and a slope value of 0.841. A similar correlation was observed between DOC and NHS concentrations, with a smaller slope value of 0.159. However, the correlation coefficient of the latter was much larger when the data was regressed to a logarithmic curve. These observations suggest the presence of a general tendency that the increased DOC in the river waters was mainly due to the increased supply of HS from wetland soils, whereas the rate of the increase in the NHS supply has an upper limit which may be controlled by primary productivity.
    Matched MeSH terms: Carbon/chemistry*
  7. Carbon dioxide conversion over carbon-based nanocatalysts
    Khavarian M, Chai SP, Mohamed AR
    J Nanosci Nanotechnol, 2013 Jul;13(7):4825-37.
    PMID: 23901504
    The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.
    Matched MeSH terms: Carbon/chemistry*
  8. Upgradation of chemical, fuel, thermal, and structural properties of rice husk through microwave-assisted hydrothermal carbonization
    Nizamuddin S, Siddiqui MTH, Baloch HA, Mubarak NM, Griffin G, Madapusi S, et al.
    Environ Sci Pollut Res Int, 2018 Jun;25(18):17529-17539.
    PMID: 29663294 DOI: 10.1007/s11356-018-1876-7
    The process parameters of microwave hydrothermal carbonization (MHTC) have significant effect on yield of hydrochar. This study discusses the effect of process parameters on hydrochar yield produced from MHTC of rice husk. Results revealed that, over the ranges tested, a lower temperature, lower reaction time, lower biomass to water ratio, and higher particle size produce more hydrochar. Maximum hydrochar yield of 62.8% was obtained at 1000 W, 220 °C, and 5 min. The higher heating value (HHV) was improved significantly from 6.80 MJ/kg of rice husk to 16.10 MJ/kg of hydrochar. Elemental analysis results showed that the carbon content increased and oxygen content decreased in hydrochar from 25.9 to 47.2% and 68.5 to 47.0%, respectively, improving the energy and combustion properties. SEM analysis exhibited modification in structure of rice husk and improvement in porosity after MHTC, which was further confirmed from BET surface analysis. The BET surface area increased from 25.0656 m2/g (rice husk) to 92.6832 m2/g (hydrochar). Thermal stability of hydrochar was improved from 340 °C for rice husk to 370 °C for hydrochar.
    Matched MeSH terms: Carbon/chemistry*
  9. A sustainable and economical solution for CO2 capture with biobased carbon materials derived from palm kernel shells
    Gopalan J, Buthiyappan A, Rashidi NA, Sufian S, Abdul Raman AA
    Environ Sci Pollut Res Int, 2024 Jul;31(33):45887-45912.
    PMID: 38980479 DOI: 10.1007/s11356-024-34173-1
    This study investigates the synthesize of activated carbon for carbon dioxide adsorption using palm kernel shell (PKS), a by-product of oil palm industry. The adsorbent synthesis involved a simple two-step carbonization method. Firstly, PKS was activated with potassium oxide (KOH), followed by functionalization with magnesium oxide (MgO). Surface analysis revealed that KOH activated PKS has resulted in a high specific surface area of 1086 m2/g compared to untreated PKS (435 m2/g). However, impregnation of MgO resulted in the reduction of surface area due to blockage of pores by MgO. Thermogravimetric analysis (TGA) demonstrated that PKS-based adsorbents exhibited minimal weight loss of less than 30% up to 500 °C, indicating their suitability for high-temperature applications. CO2 adsorption experiments revealed that PKS-AC-MgO has achieved a higher adsorption capacity of 155.35 mg/g compared to PKS-AC (149.63 mg/g) at 25 °C and 5 bars. The adsorption behaviour of PKS-AC-MgO was well fitted by both the Sips and Langmuir isotherms, suggesting a combination of both heterogeneous and homogeneous adsorption and indicating a chemical reaction between MgO and CO2. Thermodynamic analysis indicated a spontaneous and thermodynamically favourable process for CO2 capture by PKS-AC-MgO, with negative change in enthalpy (- 0.21 kJ/mol), positive change in entropy (2.44 kJ/mol), and negative change in Gibbs free energy (- 729.61 J/mol, - 790.79 J/mol, and - 851.98 J/mol) across tested temperature. Economic assessment revealed that the cost of PKS-AC-MgO is 21% lower than the current market price of commercial activated carbon, indicating its potential for industrial application. Environmental assessment shows a significant reduction in greenhouse gas emissions (381.9 tCO2) through the utilization of PKS-AC-MgO, underscoring its environmental benefits. In summary, the use of activated carbon produced from PKS and functionalised with MgO shows great potential for absorbing CO2. This aligns with the ideas of a circular economy and sustainable development.
    Matched MeSH terms: Carbon/chemistry
  10. Biomass derived green carbon dots for sensing applications of effective detection of metallic contaminants in the environment
    Bosu S, Rajamohan N, Sagadevan S, Raut N
    Chemosphere, 2023 Dec;345:140471.
    PMID: 37871875 DOI: 10.1016/j.chemosphere.2023.140471
    The rapid consumption of metals and unorganized disposal have led to unprecedented increases in heavy metal ion concentrations in the ecosystem, which disrupts environmental homeostasis and results in agricultural biodiversity loss. Mitigation and remediation plans for heavy metal pollution are largely dependent on the discovery of cost-effective, biocompatible, specific, and robust detectors because conventional methods involve sophisticated electronics and sample preparation procedures. Carbon dots (CDs) have gained significant importance in sensing applications related to environmental sustainability. Fluorescence sensor applications have been enhanced by their distinctive spectral properties and the potential for developing efficient photonic devices. With the recent development of biomass-functionalized carbon dots, a wide spectrum of multivalent and bivalent transition metal ions responsible for water quality degradation can be detected with high efficiency and minimal toxicity. This review explores the various methods of manufacturing carbon dots and the biochemical mechanisms involved in metal detection using green carbon dots for sensing applications involving Cu (II), Fe (III), Hg (II), and Cr (VI) ions in aqueous systems. A detailed discussion of practical challenges and future recommendations is presented to identify feasible design routes.
    Matched MeSH terms: Carbon/chemistry
  11. Immobilized acclimated biomass-powdered activated carbon for the bioregeneration of granular activated carbon loaded with phenol and o-cresol
    Toh RH, Lim PE, Seng CE, Adnan R
    Bioresour Technol, 2013 Sep;143:265-74.
    PMID: 23796608 DOI: 10.1016/j.biortech.2013.05.126
    The objectives of the study are to use immobilized acclimated biomass and immobilized biomass-powdered activated carbon (PAC) as a novel approach in the bioregeneration of granular activated carbon (GAC) loaded with phenol and o-cresol, respectively, and to compare the efficiency and rate of the bioregeneration of the phenolic compound-loaded GAC using immobilized and suspended biomasses under varying GAC dosages. Bioregeneration of GAC loaded with phenol and o-cresol, respectively, was conducted in batch system using the sequential adsorption and biodegradation approach. The results showed that the bioregeneration efficiency of GAC loaded with phenol or o-cresol was basically the same irrespective of whether the immobilized or suspended biomass was used. Nonetheless, the duration for bioregeneration was longer under immobilized biomass. The beneficial effect of immobilized PAC-biomass for bioregeneration is the enhancement of the removal rate of the phenolic compounds via adsorption and the shortening of the bioregeneration duration.
    Matched MeSH terms: Carbon/chemistry*
  12. Evaluation of carbon-based nanosorbents synthesised by ethylene decomposition on stainless steel substrates as potential sequestrating materials for nickel ions in aqueous solution
    Lee XJ, Lee LY, Foo LP, Tan KW, Hassell DG
    J Environ Sci (China), 2012;24(9):1559-68.
    PMID: 23520862
    The present work covers the preparation of carbon-based nanosorbents by ethylene decomposition on stainless steel mesh without the use of external catalyst for the treatment of water containing nickel ions (Ni2+). The reaction temperature was varied from 650 to 850 degrees C, while reaction time and ethylene to nitrogen flow ratio were maintained at 30 min and 1:1 cm3/min, respectively. Results show that nanosorbents synthesised at a reaction temperature of 650 degrees C had the smallest average diameter (75 nm), largest BET surface area (68.95 m2/g) and least amount of impurity (0.98 wt.% Fe). A series of batch-sorption tests were performed to evaluate the effects of initial pH, initial metal concentration and contact time on Ni2+ removal by the nanosorbents. The equilibrium data fitted well to Freundlich isotherm. The kinetic data were best correlated to a pseudo second-order model indicating that the process was of chemisorption type. Further analysis by the Boyd kinetic model revealed that boundary layer diffusion was the controlling step. This primary study suggests that the prepared material with Freundlich constants compared well with those in the literature, is a promising sorbent for the sequestration of Ni2+ in aqueous solutions.
    Matched MeSH terms: Nanotubes, Carbon/chemistry*
  13. Optimization of basic dye removal by oil palm fibre-based activated carbon using response surface methodology
    Hameed BH, Tan IA, Ahmad AL
    J Hazard Mater, 2008 Oct 30;158(2-3):324-32.
    PMID: 18329169 DOI: 10.1016/j.jhazmat.2008.01.088
    Oil palm fibre was used to prepare activated carbon using physiochemical activation method which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO(2)) gasification. The effects of three preparation variables: the activation temperature, activation time and chemical impregnation (KOH:char) ratio on methylene blue (MB) uptake from aqueous solutions and activated carbon yield were investigated. Based on the central composite design (CCD), a quadratic model and a two factor interaction (2FI) model were respectively developed to correlate the preparation variables to the MB uptake and carbon yield. From the analysis of variance (ANOVA), the significant factors on each experimental design response were identified. The optimum activated carbon prepared from oil palm fibre was obtained by using activation temperature of 862 degrees C, activation time of 1h and chemical impregnation ratio of 3.1. The optimum activated carbon showed MB uptake of 203.83 mg/g and activated carbon yield of 16.50%. The equilibrium data for adsorption of MB on the optimum activated carbon were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 400mg/g at 30 degrees C.
    Matched MeSH terms: Carbon/chemistry*
  14. Preparation and characterization of activated carbon from palm shell by chemical activation with K2CO3
    Adinata D, Wan Daud WM, Aroua MK
    Bioresour Technol, 2007 Jan;98(1):145-9.
    PMID: 16380249
    Palm shell was used to prepare activated carbon using potassium carbonate (K2CO3) as activating agent. The influence of carbonization temperatures (600-1000 degrees C) and impregnation ratios (0.5-2.0) of the prepared activated carbon on the pore development and yield were investigated. Results showed that in all cases, increasing the carbonization temperature and impregnation ratio, the yield decreased, while the adsorption of CO2 increased, progressively. Specific surface area of activated carbon was maximum about 1170 m2/g at 800 degrees C with activation duration of 2 h and at an impregnation ratio of 1.0.
    Matched MeSH terms: Carbon/chemistry*
  15. Fulltext Low temperature hall effect investigation of conducting polymer-carbon nanotubes composite network
    Bahrami A, Talib ZA, Yunus WM, Behzad K, M Abdi M, Din FU
    Int J Mol Sci, 2012;13(11):14917-28.
    PMID: 23203102 DOI: 10.3390/ijms131114917
    Polypyrrole (PPy) and polypyrrole-carboxylic functionalized multi wall carbon nanotube composites (PPy/f-MWCNT) were synthesized by in situ chemical oxidative polymerization of pyrrole on the carbon nanotubes (CNTs). The structure of the resulting complex nanotubes was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effects of f-MWCNT concentration on the electrical properties of the resulting composites were studied at temperatures between 100 K and 300 K. The Hall mobility and Hall coefficient of PPy and PPy/f-MWCNT composite samples with different concentrations of f-MWCNT were measured using the van der Pauw technique. The mobility decreased slightly with increasing temperature, while the conductivity was dominated by the gradually increasing carrier density.
    Matched MeSH terms: Nanotubes, Carbon/chemistry*
  16. Carbonaceous materials and their advances as a counter electrode in dye-sensitized solar cells: challenges and prospects
    Kouhnavard M, Ludin NA, Ghaffari BV, Sopian K, Ikeda S
    ChemSusChem, 2015 May 11;8(9):1510-33.
    PMID: 25925421 DOI: 10.1002/cssc.201500004
    Dye-sensitized solar cells (DSSCs) serve as low-costing alternatives to silicon solar cells because of their low material and fabrication costs. Usually, they utilize Pt as the counter electrode (CE) to catalyze the iodine redox couple and to complete the electric circuit. Given that Pt is a rare and expensive metal, various carbon materials have been intensively investigated because of their low costs, high surface areas, excellent electrochemical stabilities, reasonable electrochemical activities, and high corrosion resistances. In this feature article, we provide an overview of recent studies on the electrochemical properties and photovoltaic performances of carbon-based CEs (e.g., activated carbon, nanosized carbon, carbon black, graphene, graphite, carbon nanotubes, and composite carbon). We focus on scientific challenges associated with each material and highlight recent advances achieved in overcoming these obstacles. Finally, we discuss possible future directions for this field of research aimed at obtaining highly efficient DSSCs.
    Matched MeSH terms: Carbon/chemistry*
  17. Fabrication and characterization of DLC coated microdimples on hip prosthesis heads
    Choudhury D, Ay Ching H, Mamat AB, Cizek J, Abu Osman NA, Vrbka M, et al.
    J Biomed Mater Res B Appl Biomater, 2015 Jul;103(5):1002-12.
    PMID: 25220737 DOI: 10.1002/jbm.b.33274
    Diamond like carbon (DLC) is applied as a thin film onto substrates to obtain desired surface properties such as increased hardness and corrosion resistance, and decreased friction and wear rate. Microdimple is an advanced surface modification technique enhancing the tribological performance. In this study, DLC coated microdimples were fabricated on hip prosthesis heads and their mechanical, material and surface properties were characterized. An Electro discharge machining (EDM) oriented microdrilling was utilized to fabricate a defined microdimple array (diameter of 300 µm, depth of 70 µm, and pitch of 900 µm) on stainless steel (SS) hip prosthesis heads. The dimpled surfaces were then coated by hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) layers by using a magnetron sputtering technology. A preliminary tribology test was conducted on these fabricated surfaces against a ceramic ball in simulated hip joint conditions. It was found that the fabricated dimples were perpendicular to the spherical surfaces and no cutting-tools wear debris was detected inside the individual dimples. The a-C:H and Ta-C coatings increased the hardness at both the dimple edges and the nondimpled region. The tribology test showed a significant reduction in friction coefficient for coated surfaces regardless of microdimple arrays: the lowest friction coefficient was found for the a-C:H samples (µ = 0.084), followed by Ta-C (µ = 0.119), as compared to the SS surface (µ = 0.248).
    Matched MeSH terms: Carbon/chemistry*
  18. Toxicity of Carbon Nanotubes: Molecular Mechanisms, Signaling Cascades, and Remedies in Biomedical Applications
    Saleemi MA, Hosseini Fouladi M, Yong PVC, Chinna K, Palanisamy NK, Wong EH
    Chem Res Toxicol, 2021 01 18;34(1):24-46.
    PMID: 33319996 DOI: 10.1021/acs.chemrestox.0c00172
    Carbon nanotubes (CNTs) are the most studied allotropic form of carbon. They can be used in various biomedical applications due to their novel physicochemical properties. In particular, the small size of CNTs, with a large surface area per unit volume, has a considerable impact on their toxicity. Despite of the use of CNTs in various applications, toxicity is a big problem that requires more research. In this Review, we discuss the toxicity of CNTs and the associated mechanisms. Physicochemical factors, such as metal impurities, length, size, solubilizing agents, CNTs functionalization, and agglomeration, that may lead to oxidative stress, toxic signaling pathways, and potential ways to control these mechanisms are also discussed. Moreover, with the latest mechanistic evidence described in this Review, we expect to give new insights into CNTs' toxicological effects at the molecular level and provide new clues for the mitigation of harmful effects emerging from exposure to CNTs.
    Matched MeSH terms: Nanotubes, Carbon/chemistry
  19. 2D Graphene oxide (GO) doped p-n type BiOI/Bi2WO6 as a novel composite for photodegradation of bisphenol A (BPA) in aqueous solutions under UV-vis irradiation
    Mengting Z, Kurniawan TA, Yanping Y, Avtar R, Othman MHD
    Mater Sci Eng C Mater Biol Appl, 2020 Mar;108:110420.
    PMID: 31924000 DOI: 10.1016/j.msec.2019.110420
    Bisphenol A (BPA) is a refractory pollutant presents in water body that possesses serious threats to living organisms. To deal with it, we investigate and evaluate the effectiveness of GO@BiOI/Bi2WO6 composite as a novel photocatalyst for BPA removal from aqueous solutions under UV-vis irradiation. To enhance its removal for BPA, the surface of BiOI/Bi2WO6 is modified with graphene oxide (GO). This composite is named as 'GO@BiOI/Bi2WO6'. Changes in its physico-chemical properties after surface modification with GO are characterized by XRD, FTIR, FESEM-EDS, XPS, PL, and BET methods. Optimized conditions of BPA degradation by the composite are determined under identical conditions. Photodegradation pathways of BPA and its removal mechanisms by the same composite are presented. It is obvious that the GO@BiOI/Bi2WO6 has demonstrated its potential as a promising photocatalyst for BPA removal under UV-vis irradiation. About 81% of BPA removal is attained by the GO@BiOI/Bi2WO6 under optimized conditions (10 mg/L of BPA, 0.5 g/L of dose, pH 7 and 5 h of reaction time). The oxidation by-products of BPA degradation include p-hydroquinone or 4-(1-hydroxy-1-methyl-ethyl)-phenol. In spite of its performance, the treated effluents are still unable to meet the maximum discharge limit of <1 mg/L set by national legislation. Therefore, subsequent biological processes are essential to maximize its biodegradation in the wastewater samples before their discharge into waterbody.
    Matched MeSH terms: Carbon/chemistry
  20. Synthesis of carbon-based quantum dots from starch extracts: Optical investigations
    Al-Douri Y, Badi N, Voon CH
    Luminescence, 2018 Mar;33(2):260-266.
    PMID: 29024360 DOI: 10.1002/bio.3408
    Carbon-based quantum dots (C-QDs) were synthesized through microwave-assisted carbonization of an aqueous starch suspension mediated by sulphuric and phosphoric acids. The as-prepared C-QDs showed blue, green and yellow luminescence without the addition of any surface-passivating agent. The C-QDs were further analyzed by UV-vis spectroscopy to measure the optical response of the organic compound. The energy gaps revealed narrow sizing of C-QDs in the semiconductor range. The optical refractive index and dielectric constant were investigated. The C-QDs size distribution was characterized. The results suggested an easy route to the large scale production of C-QDs materials.
    Matched MeSH terms: Carbon/chemistry*
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