Displaying publications 41 - 60 of 878 in total

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  1. Ooi CH, Cheah WK, Sim YL, Pung SY, Yeoh FY
    J Environ Manage, 2017 Jul 15;197:199-205.
    PMID: 28384613 DOI: 10.1016/j.jenvman.2017.03.083
    Urea removal is an important process in household wastewater purification and hemodialysis treatment. The efficiency of the urea removal can be improved by utilizing activated carbon fiber (ACF) for effective urea adsorption. In this study, ACF was prepared from oil palm empty fruit bunch (EFB) fiber via physicochemical activation using sulfuric acid as an activating reagent. Based on the FESEM result, ACF obtained after the carbonization and activation processes demonstrated uniform macropores with thick channel wall. ACF was found better prepared in 1.5:1 acid-to-EFB fiber ratio; where the pore size of ACF was analyzed as 1.2 nm in diameter with a predominant micropore volume of 0.39 cm(3) g(-1) and a BET surface area of 869 m(2) g(-1). The reaction kinetics of urea adsorption by the ACF was found to follow a pseudo-second order kinetic model. The equilibrium amount of urea adsorbed on ACF decreased from 877.907 to 134.098 mg g(-1) as the acid-to-fiber ratio increased from 0.75 to 4. During the adsorption process, the hydroxyl (OH) groups on ACF surface were ionized and became electronegatively charged due to the weak alkalinity of urea solution, causing ionic repulsion towards partially anionic urea. The ionic repulsion force between the electronegatively charged ACF surface and urea molecules became stronger when more OH functional groups appeared on ACF prepared at higher acid impregnation ratio. The results implied that EFB fiber based ACF can be used as an efficient adsorbent for the urea removal process.
    Matched MeSH terms: Adsorption
  2. Hamzah, I.H., Sidek, O., Abd Manaf, A.
    ASM Science Journal, 2010;4(2):142-148.
    MyJurnal
    A preliminary study was carried out to fabricate a three electrode system based on electrochemical sensoring. The cyclic voltammetry (CV) technique was chosen to select the type of metal suitable for evaporation and to compare the results produced from the fabricated gold electrode with the conventional macro-electrode system. The methodology and apparatus used involved low cost apparatus and methodology such as soft lithography, wet-etching, thermal evaporation, direct current sputtering, polymethylmethacrylate moulding and polydimethylsiloxane coating. The experiment was conducted at a fixed scan rate of 100 mV/s by using 0.01 M K3Fe(CN)6 in 0.1M KCl and well known method using Randles-Sevcik equation, peak current ratio and voltage separation was used to analyze the characterization on the fabricated sensors. Electrodes of 6.5 mm2 and 0.26 mm2 were fabricated to prove the adsorption effect of the reactant and the influence of the electrode area on the value of the peak current. CV analysis proved that the fabricated sensor was reliable for a range of 24 h at 25ºC room temperature.
    Matched MeSH terms: Adsorption
  3. Nor Azah Yusof, Beyan, Appri, Md. Haron Jelas, Nor Azowa Ibrahim
    MyJurnal
    A molecularly imprinted polymer (MIP), with the ability to bind Pb(II) ion, was prepared using the non-covalent molecular imprinting methods and evaluated as a sorbent for the Pb(II) ion uptake. 4-vinylbenzoic acid was chosen as the complexing monomer. The imprinted polymer was synthesized by radical polymerization. The template (Pb(II) ions) was removed using 0.1 M HCl. As a result, the efficient adsorption was found to occur at pH 7. The result also showed the applicability of the Langmuir model for the sorption, with the maximum sorption capacity of 204.08 μg/mg.
    Matched MeSH terms: Adsorption
  4. Syafiuddin A, Salmiati S, Jonbi J, Fulazzaky MA
    J Environ Manage, 2018 Jul 15;218:59-70.
    PMID: 29665487 DOI: 10.1016/j.jenvman.2018.03.066
    It is the first time to do investigation the reliability and validity of thirty kinetic and isotherm models for describing the behaviors of adsorption of silver nanoparticles (AgNPs) onto different adsorbents. The purpose of this study is therefore to assess the most reliable models for the adsorption of AgNPs onto feasibility of an adsorbent. The fifteen kinetic models and fifteen isotherm models were used to test secondary data of AgNPs adsorption collected from the various data sources. The rankings of arithmetic mean were estimated based on the six statistical analysis methods of using a dedicated software of the MATLAB Optimization Toolbox with a least square curve fitting function. The use of fractal-like mixed 1, 2-order model for describing the adsorption kinetics and that of Fritz-Schlunder and Baudu models for describing the adsorption isotherms can be recommended as the most reliable models for AgNPs adsorption onto the natural and synthetic adsorbent materials. The application of thirty models have been identified for the adsorption of AgNPs to clarify the usefulness of both groups of the kinetic and isotherm equations in the rank order of the levels of accuracy, and this significantly contributes to understandability and usability of the proper models and makes to knowledge beyond the existing literatures.
    Matched MeSH terms: Adsorption
  5. Vakili M, Amouzgar P, Cagnetta G, Wang B, Guo X, Mojiri A, et al.
    Polymers (Basel), 2019 Oct 16;11(10).
    PMID: 31623271 DOI: 10.3390/polym11101701
    A composite chitosan/nano-activated carbon (CS-NAC) aminated by (3-aminopropyl)triethoxysilane (APTES) was prepared in the form of beads and applied for the removal of acetaminophen from aqueous solutions. NAC and APTES concentrations were optimized to obtain a suitable adsorbent structure for enhanced removal of the pharmaceutical. The aminated adsorbent (CS-NAC-APTES beads) prepared with 40% w/w NAC and 2% v/v APTES showed higher adsorption capacity (407.83 mg/g) than CS-NAC beads (278.4 mg/g). Brunauer-Emmett-Teller (BET) analysis demonstrated that the surface area of the CS-NAC-APTES beads was larger than that of CS-NAC beads (1.16 times). The adsorption process was well fitted by the Freundlich model (R2 > 0.95), suggesting a multilayer adsorption. The kinetic study also substantiated that the pseudo-second-order model (R2 > 0.98) was in better agreement with the experimental data. Finally, it was proved that the prepared beads can be recycled (by washing with NaOH solution) at least 5 times before detectable performance loss.
    Matched MeSH terms: Adsorption
  6. Kutty SRM, Almahbashi NMY, Nazrin AAM, Malek MA, Noor A, Baloo L, et al.
    Heliyon, 2019 Oct;5(10):e02439.
    PMID: 31667371 DOI: 10.1016/j.heliyon.2019.e02439
    Treated palm oil mill effluents (POME) is of great concern as it still has colour from its dissolved organics which may pollute receiving water bodies. In this study, the removal of colour from treated palm oil mill effluent were investigated through adsorption studies using carbon derived from wastewater sludge (WSC). Sludge from activated sludge plants were dried and processed to produce WSC. In this study, three different bed depths of WSC were used: 5 cm, 10 cm, and 15 cm. For each bed depth, the flowrate was varied at three different values: 100 mL/hr, 50 mL/hr and 25 mL/hr. It was found that at bed depth of 5 cm, the breakthrough curves were occurred at 360 min, 150 min and 15 min for flowrates of 25, 50 and 100 mL/hr respectively. It was observed that at a particular depth the exhaustion time for column reduced as flow rate increases. Kinetic models, Adams-Bohart and Yoon-Nelson were used to analyze the performance of the adsorption. It was found that rate constant for Adams Bohart model decreased with the increase in bed depth. Adsorption capacity obtained from Adams-Bohart model ranged from 2676.19 mg/L up to 8938.78 mg/L. The maximum adsorption capacity increases with smaller bed depth. For Yoon-Nelson model, the rate constant decreases with increase in bed depth. The required time for 50% breakthrough obtained from the models ranged from 17.01 to 104.17 minutes for all three bed depths. The reduction of colour was found to be effective at all bed depths. The experimental data was best described by both models as with higher values of correlation coefficient (R2).
    Matched MeSH terms: Adsorption
  7. Abdul Wahab Mohammad, Mohd Tusirin Mohd Nor, Siti Rozaimah Sheikh Abdullah, Hassimi Abu Hasan, Muhammad Said
    Sains Malaysiana, 2015;44:421-427.
    Palm oil mill effluent (POME) treatment has developed in the last decade. Due to the characteristic and volume of POME,
    it needed a complete treatment to reduce the pollutant content. Three pre-treatments method, ultrafiltration, adsorption
    and decantation were applied prior to nanofiltration (NF) membrane. The polyethersulphone membrane, montmorillonite
    as the adsorbent and modern decanter was investigated in this research. Two types of NF membrane, named NF-1 and
    NF-ASP30 were used after pre-treatment. The removal of four important parameters were determined i.e. COD, TSS, colour
    and turbidity. The results showed that the adsorption and UF is better than decantation pre-treatment. The ultrafiltration
    and adsorption can reduce POME content more than 80% for all parameter while decantation varied between 40 and 80%.
    The combination of ultrafiltration and adsorption with both of NF membrane can removed almost all the parameter. But
    the decantation can only remove the turbidity but not for the rest of the parameters. Besides the POME content, the flux
    decline for both of NF membrane was also investigated. The flux of NF-1 membrane was higher than NF-ASP30 membrane
    but NF-ASP was more relative stable for the flux decline. Overall, NF-1 has better performance in flux decline.
    Matched MeSH terms: Adsorption
  8. Wan Zuhairi W, Abdul Rahim S
    Sains Malaysiana, 2007;36:149-157.
    The sorption parameters of two heavy metals (i.e. Pb and Cu) in clay soils from Selangor were studied using batch equilibrium test. The test was conducted in two separate systems, i.e. single and mix solutions. The sorption isotherms data from this test were then used to calculate the sorption parameters, i.e. distribution coefficient (Kd) and maximum adsorption capacity (Am). Langmuir sorption equation was used to model the sorption data with the correlation coefficients (r2) higher than 0.6. The study has revealed that different soils have different sorption capacity for different heavy metals. The Kd values are proportional to the sorption capacity of the soils. The sorption of Pb and Cu in single solution is higher than in mix solution, due to the competition for sorption sites among heavy metals in mix solution. The Kd values for Pb in single solution ranging from 36.18-334.48 L/g and for Cu is 9.29-66.19 L/g. In mix solution, the Kd values for Pb and Cu are much smaller, ranging from 23.13-31.79 L/g and 3.95-18.53 L/g respectively. The Am values in single solution for both Pb and Cu are ranging from 0.48-1.09 mg/g dan 0.18-0.70 mg/g respectively. While in mix solution, the values of Am for Pb ranging from 0.20-1.11 mg/g and Cu within 0.18-0.60 mg/g.
    Matched MeSH terms: Adsorption
  9. Zalina Laili, Muhamad Samudi Yasir, Muhamat Omar, Mohd Zaidi Ibrahim, Philip E
    Sains Malaysiana, 2010;39:333-336.
    This study examines the influence of humic acids (HA) on adsorption of radium (Ra) ions onto coir pith (CP) in aqueous solution. The adsorption behaviours of Ra ions onto CP under the influence of HA in aqueous solution were investigated in the series of batch mode adsorption experiments. The effects of various experimental conditions such as pH, contact time, adsorbent dosage and initial concentration of Ra ions have been studied. The results revealed that the presence of HA in aqueous solution enhanced the adsorption of Ra ions onto CP. The adsorption results showed that the percentage of Ra adsorbed was increased with an increase in the pH or alkalinity of aqueous solutions. Time dependence of the batch studies showed that a contact time of one day was sufficient to reach equilibrium. The result also showed that there was no significant difference on the effect of adsorbent dose on adsorption of radium onto CP. It was shown that the equilibrium data could be fitted by Freundlich equation.
    Matched MeSH terms: Adsorption
  10. Muhammad Abbas Ahmad Zaini, Tan Wee Meng, Mohd. Johari Kamaruddin, Siti Hamidah Mohd Setapar, Mohd. Azizi Che Yunus
    Sains Malaysiana, 2014;43:1421-1428.
    This work is aimed to determine the characteristics of activated carbons derived from palm kernel shell (PKS) by microwave-induced zinc chloride activation for dye removal. Activation was performed in a microwave oven at power intensity of 70% for 10 min. The same procedures were repeated for activation using recycled ZnCl2 solution from the first activation. The activated carbons were characterized according to surface area, morphology, functional groups and batch adsorption. The yield for the first activation was 70.7% with surface area of 858m2/g. It was found that the activated carbon prepared using the recycled ZnCl2 still possesses good surface area for methylene blue removal. The adsorption behaviour of the continuous system was well fitted to and could be satisfactorily described by the Yoon and Nelson model.
    Matched MeSH terms: Adsorption
  11. Tran HN, Pham VV, Vo DN, Nguyen-Tri P
    Chemosphere, 2019 Oct;233:988-990.
    PMID: 30853115 DOI: 10.1016/j.chemosphere.2019.02.084
    This article aims to discuss (1) the incorrect identification of Cr(III) and Cr(VI) binding energies in the Cr 2p XPS (X-ray photoelectron spectroscopy) spectra of the laden adsorbent (the nZVI-BC sample after Cr(VI) adsorption), (2) misconception regarding the Weber-Morris intraparticle diffusion model, and (3) inconsistency between the experiential data and the Thomas adsorption rate constants. The authors hope that our comments are beneficial for other researchers to avoid the undesirable mistakes.
    Matched MeSH terms: Adsorption
  12. Hosseingholi Pourasl A, Ariffin SHS, Ahmadi MT, Ismail R, Gharaei N
    Beilstein J Nanotechnol, 2019;10:644-653.
    PMID: 30931206 DOI: 10.3762/bjnano.10.64
    Nanomaterial-based sensors with high sensitivity, fast response and recovery time, large detection range, and high chemical stability are in immense demand for the detection of hazardous gas molecules. Graphene nanoribbons (GNRs) which have exceptional electrical, physical, and chemical properties can fulfil all of these requirements. The detection of gas molecules using gas sensors, particularly in medical diagnostics and safety applications, is receiving particularly high demand. GNRs exhibit remarkable changes in their electrical characteristics when exposed to different gases through molecular adsorption. In this paper, the adsorption effects of the target gas molecules (CO and NO) on the electrical properties of the armchair graphene nanoribbon (AGNR)-based sensor are analytically modelled. Thus, the energy dispersion relation of AGNR is developed considering the molecular adsorption effect using a tight binding (TB) method. The carrier velocity is calculated based on the density of states (DOS) and carrier concentration (n) to obtain I-V characteristics and to monitor its variation in the presence of the gas molecules. Furthermore, the I-V characteristics and energy band structure of the AGNR sensor are simulated using first principle calculations to investigate the gas adsorption effects on these properties. To ensure the accuracy of the proposed model, the I-V characteristics of the AGNR sensor that are simulated based both on the proposed model and first principles calculations are compared, and an acceptable agreement is achieved.
    Matched MeSH terms: Adsorption
  13. Kaewbuddee C, Chanpiwat P, Kidkhunthod P, Wantala K
    Sains Malaysiana, 2016;45:1155-1167.
    The aims of this work were to investigate the characteristics of nanoscale zero valent irons (nZVI) coupled with mesoporous
    materials (RH-MCM-41) adsorbent and to study the removal mechanisms of Pb (II) from synthetical solutions using full
    pictorial design batch experiments. Synthetic nZVI coupled with RH MCM-41 as Pb (II) adsorbent were characterized
    by XRD, TEM, BET and XANES. The results of XANES analyses confirmed the ability of RH-MCM-41 to prevent oxidations of
    Fe0
    to Fe2+ and Fe3+. XANES results also verified the oxidation states of Pb (II). The solution pH was the most significant
    positive effect in controlling Pb (II) adsorption. The equilibrium and kinetic adsorption isotherms well fitted with the
    Langmuir isotherm. The pseudo-second order kinetic adsorption indicated that the adsorption process is the rate limiting
    step for Pb (II) removal. Furthermore, Langmuir-Hinshelwood confirmed the obvious Pb (II) adsorption at the active
    site of adsorbents. The reduction rate constant (kr
    = 5,000 mg/L.min) was higher than the adsorption rate constant (Kad
    = 0.0002 L/mg). Regarding the research results, four pathways including: reduction process, adsorption on FeOOH,
    adsorption on RH-MCM-41 and complex reaction between Fe and Pb ions were suggested for Pb (II) removal by nZVI
    coupled with RH-MCM-41.
    Matched MeSH terms: Adsorption
  14. Rabeea Munawar, Ehsan Ullah Mughal, Muhammad Waseem Mumtaz, Muhammad Zubair, Jamshaid Ashraf, Zofishan Yousaf, et al.
    Sains Malaysiana, 2018;47:27-34.
    The prime objective of the present research work was to evaluate the efficiency of bio-machine for the removal of Cadmium (Cd) from aquatic systems. Aspergillus niger fungus was used as bio-machine to remove Cd from aquatic systems. Twenty three different strains (IIB-1 to IIB-23) were isolated from industrial effluents and the Langmuir and Freundlich models were applied to the best Cadmium removal strain IIB-23 in order to obtain the adsorption parameters. Different parameters such as pH, temperature, contact time, initial metal concentratio, and biomass dosage on the biosorption of Cd were studied. The percent removal of Cd initially increased with an increase in pH ranging from 5.5-6.5 and then decreased by increasing pH from 7.0-7.5. An optimized pH used for Cd removal from aquatic systems was found to be 6.5. Additionally, an optimum amount of biomass was 1.33 g for the maximum removal of Cd from the aqueous solutions with initial metal concentration of 75 mg/L. The results obtained thus indicated that Langmuir model is the best suited for the removal of Cd from aquatic systems.
    Matched MeSH terms: Adsorption
  15. Ma J, Ma NL, Zhang D, Wu N, Liu X, Meng L, et al.
    Chemosphere, 2022 Apr;292:133345.
    PMID: 34922964 DOI: 10.1016/j.chemosphere.2021.133345
    Zero waste multistage utilization of biomass from Ginkgo biloba branches (GBBs) was achieved through extraction of bioactive components, analysis of antioxidant and antibacterial activities, preparation and composition of pyrolyzate, adsorption and reuse of modified biochar. The results showed that GBBs had abundant bioactive components for potential application in the industry of food, chemical raw materials and biomedicine. Especially, the bioactive compounds in acetone extract (10 mg/mL) of GBBs identified by DPPH and ABTS had free radical scavenging abilities of 92.28% and 98.18%, respectively, which are equivalent to Vitamin C used as an antioxidant in food additives. Fourier Transform Infrared and X-Ray Diffraction analysis showed that carboxymethyl cellulose (CMC) and magnetic Fe3O4 were successfully incorporated into raw biochar (RB) to form CMC-Fe3O4-RB nanomaterial. Scanning electron microscopy and X-Ray Diffraction spectroscopy displayed Fe, C, and O existed on the surface of CMC-Fe3O4-RB. Compared with RB, CMC-Fe3O4-RB had a larger specific surface area, pore volume and pore size. Meanwhile, nanomagnetic CMC-Fe3O4-RB solved the problem of agglomeration in traditional magnetized biochar production, and improved the adsorption capacity of Pb2+, which was 29.90% higher than that of RB by ICP-OES. Further, the Pb2+ (10 mg/L) adsorption capacity of CMC-Fe3O4-RB reached the highest level in 2 h at the dosage of 0.01 g/L, and remained stable at 52.987 mg/g after five cycles of adsorption and desorption. This research aided in the creation of a strategy for GBBs zero waste multistage usage and a circular economic model for GBBs industry development, which can be promoted and applied to the fields of food industry and environment improvement.
    Matched MeSH terms: Adsorption
  16. Tran TV, Nguyen DTC, Nguyen TTT, Nguyen DH, Alhassan M, Jalil AA, et al.
    Sci Total Environ, 2023 Jan 15;856(Pt 1):158817.
    PMID: 36116641 DOI: 10.1016/j.scitotenv.2022.158817
    Each year, nearly 30 million tons of pineapple fruit are harvested for food and drinking industries, along with the release of a huge amount of pineapple wastes. Without the proper treatment, pineapple wastes can cause adverse impacts on the environment, calling for new technologies to convert them into valuable products. Here, we review the production and application of adsorbents derived from pineapple wastes. The thermal processing or chemical modification improved the surface chemistry and porosity of these adsorbents. The specific surface areas of the pineapple wastes-based adsorbents were in range from 4.2 to at 522.9 m2·g-1. Almost adsorption systems followed the pseudo second order kinetic model, and Langmuir isotherm model. The adsorption mechanism was found with the major role of electrostatic attraction, complexation, chelation, and ion exchange. The pineapple wastes based adsorbents could be easily regenerated. We suggest the potential of the pineapple wastes towards circular economy.
    Matched MeSH terms: Adsorption
  17. Chen K, Ng KH, Cheng CK, Cheng YW, Chong CC, Vo DN, et al.
    Chemosphere, 2022 Jan;287(Pt 2):132222.
    PMID: 34826917 DOI: 10.1016/j.chemosphere.2021.132222
    Biomass, which defined as plant- or animal-based materials, is intriguing tremendous scientific attentions due to its renewable attribute in serving energy security. Amongst, the plant-based biomasses, particularly those that co-generated in the agriculture activities, are commonly regarded as fuel for burning, which overlooked their hidden potentials for high-end applications. Organically, the plant-based biomass constitutes of lignocellulose components, which can be served as promising precursors for functionalized carbon materials. Meanwhile, its inorganic counterpart made up of various minerals, with Si being the most concerned one. With the advancement of biomass technologies and material synthesis in recent years, numerous attempts were endeavoured to obtain valorised products from biomass. Particularly, syntheses of catalytic and adsorptive materials are actively researched in the field of biomass reutilization. Herein, our work systematically summarized the advancements of biomass-materials for these applications in recent 10 years (2010-2020), with a special focus on the carbon-based and Si-based catalytic/adsorptive materials. Significantly, the deriving steps, inclusive of both pre-treatment and post-treatment of such materials, are incorporated in the discussion, alongside with their significances revealed too. The performance of the as-obtained materials in the respective application is systematically correlated to their physicochemical properties, hence providing valuable insights to the readers. Challenges and promising directions to be explored are raised too at the end of the review, aiming to advocate better-usage of biomass while offering great opportunities to sustain catalysis and adsorption in the industrial scale.
    Matched MeSH terms: Adsorption
  18. Chen Y, Chen Y, Shi W, Hu S, Huang Q, Liu GS, et al.
    Biosens Bioelectron, 2022 Feb 15;198:113787.
    PMID: 34864241 DOI: 10.1016/j.bios.2021.113787
    High sensitivity and capturing ratio are strongly demanded for surface plasmon resonance (SPR) sensors when applied in detection of small molecules. Herein, an SPR sensor is combined with a novel smart material, namely, MoS2 nanoflowers (MNFs), to demonstrate programmable adsorption/desorption of small bipolar molecules, i.e., amino acids. The MNFs overcoated on the plasmonic gold layer increase the sensitivity by 25% compared to an unmodified SPR sensor, because of the electric field enhancement at the gold surface. Furthermore, as the MNFs have rich edge sites and negatively charged surfaces, the MNF-SPR sensors exhibit not only much higher bipolar-molecule adsorption capability, but also efficient desorption of these molecules. It is demonstrated that the MNF-SPR sensors enable controllable detection of amino acids by adjusting solution pH according to their isoelectric points. In addition, the MNFs decorated on the plasmonic interface can be as nanostructure frameworks and modified with antibody, which allows for specific detection of proteins. This novel SPR sensor provides a new simple strategy for pre-screening of amino acid disorders in blood plasma and a universal high-sensitive platform for immunoassay.
    Matched MeSH terms: Adsorption
  19. Law XN, Cheah WY, Chew KW, Ibrahim MF, Park YK, Ho SH, et al.
    Environ Res, 2022 03;204(Pt A):111966.
    PMID: 34450156 DOI: 10.1016/j.envres.2021.111966
    Microalgae are drawing attentions among researchers for their biorefinery use or value-added products. The high production rate of biomasses produced are attractive for conversion into volatile biochar. Torrefaction, pyrolysis and hydrothermal carbonization are the recommended thermochemical conversion techniques that could produce microalgal-based biochar with desirable physiochemical properties such as high surface area and pore volume, abundant surface functional groups, as well as functionality such as high adsorption capacity. The characterizations of the biochar significantly influence the mechanisms in adsorption of pollutants from wastewaters. Specific adsorption of the organic and inorganic pollutants from the effluent are reviewed to examine the adsorption capacity and efficiency of biochar derived from different microalgae species. Last but not least, future remarks over the challenges and improvements are discussed accordingly. Overall, this review would discuss the synthesis, characterization and application of the microalgal-based biochar in wastewater.
    Matched MeSH terms: Adsorption
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