Displaying publications 1 - 20 of 29 in total

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  1. Modified Fenton oxidation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils and the potential of bioremediation as post-treatment
    Venny, Gan S, Ng HK
    Sci Total Environ, 2012 Mar 1;419:240-9.
    PMID: 22285087 DOI: 10.1016/j.scitotenv.2011.12.053
    This work focuses on the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using modified Fenton (MF) treatment coupled with a novel chelating agent (CA), a more effective technique among currently available technologies. The performance of MF treatment to promote PAH oxidation in artificially contaminated soil was investigated in a packed column with a hydrogen peroxide (H(2)O(2)) delivery system simulating in-situ soil flushing which is more representative of field conditions. The effectiveness of process parameters H(2)O(2)/soil, Fe(3+)/soil, CA/soil weight ratios and reaction time were studied using a 2(4) three level factorial design experiments. An optimised operating condition of the MF treatment was observed at H(2)O(2)/soil 0.05, Fe(3+)/soil 0.025, CA/soil 0.04 and 3h reaction time with 79.42% and 68.08% PAH removals attainable for the upper and lower parts of the soil column respectively. The effects of natural attenuation and biostimulation process as post-treatment in the remediation of the PAH-contaminated soil were also studied. In all cases, 3-aromatic ring PAH (phenanthrene) was more readily degraded than 4-aromatic ring PAH (fluoranthene) regardless of the bioremediation approach. The results revealed that both natural attenuation and biostimulation could offer remarkable enhancement of up to 6.34% and 9.38% in PAH removals respectively after 8 weeks of incubation period. Overall, the results demonstrated that combined inorganic CA-enhanced MF treatment and bioremediation serves as a suitable strategy to enhance soil quality particularly to remediate soils heavily contaminated with mixtures of PAHs.
  2. Evaluation of in situ catalysed hydrogen peroxide propagation (CHP) for phenanthrene and fluoranthene removals from soil and its associated impacts on soil functionality
    Venny, Gan S, Ng HK
    Environ Sci Pollut Res Int, 2014 Feb;21(4):2888-97.
    PMID: 24151025 DOI: 10.1007/s11356-013-2207-7
    Extensive contamination of soils by highly recalcitrant contaminants such as polycyclic aromatic hydrocarbons (PAHs) is an environmental problem arising from rapid industrialisation. This work focusses on the remediation of soil contaminated with 3- and 4-aromatic ring PAHs (phenanthrene (PHE) and fluoranthene (FLUT)) through catalysed hydrogen peroxide propagation (CHP). In the present work, the operating parameters of the CHP treatment in packed soil column was optimised with central composite design (H2O2/soil 0.081, Fe(3+)/soil 0.024, sodium pyrophosphate (SP)/soil 0.024, pH of SP solution 7.73). The effect of contaminant aging on PAH removals was also investigated. Remarkable oxidative PAH removals were observed for the short aging and extended aging period (up to 86.73 and 70.61 % for PHE and FLUT, respectively). The impacts of CHP on soil biological, chemical and physical properties were studied for both spiked and aged soils. Overall, the soil functionality analyses after the proposed operating condition demonstrated that the values for soil respiration, electrical conductivity, pH and iron precipitation fell within acceptable limits, indicating the compatibility of the CHP process with land restoration.
  3. Fulltext Full thickness macular hole: Early intervention is an important factor in visual prognosis
    Ng HK, Yaakub A, Ong LB
    Malays Fam Physician, 2014;9(3):42-8.
    PMID: 26425305 MyJurnal
    Full thickness macular hole is an eye disease, which can cause permanent visual impairment. Current advancement in vitreoretinal surgery has high success rates in repairing them, leading to a significant visual improvement, especially if patient presents early. In this article, three cases of idiopathic full thickness macular hole with different visual outcomes have been presented. All cases were referred by the primary care practitioners and had undergone macular hole surgery with the same vitreoretinal surgeon. The visual outcome was best in the patient who had the earliest presentation and referral. Early detection and referral of these patients is vital so that early surgical intervention can be carried out to improve their vision.
  4. Investigation of the impacts of ethyl lactate based Fenton treatment on soil quality for polycyclic aromatic hydrocarbons (PAHs)-contaminated soils
    Gan S, Yap CL, Ng HK, Venny
    J Hazard Mater, 2013 Nov 15;262:691-700.
    PMID: 24121640 DOI: 10.1016/j.jhazmat.2013.09.023
    This study aims to investigate the impacts of ethyl lactate (EL) based Fenton treatment on soil quality for polycyclic aromatic hydrocarbons (PAHs)-contaminated soils. Accumulation of oxygenated-polycyclic aromatic hydrocarbons (oxy-PAHs) was observed, but quantitative measurement on the most abundant compound 9,10-anthraquinone (ATQ) showed lower accumulation of the compound than that reported for ethanol (ET) based Fenton treatment. In general, as compared to conventional water (CW) based Fenton treatment, the EL based Fenton treatment exerted either a lower or higher negative impact on soil physicochemical properties depending on the property type and shared the main disadvantage of reduced soil pH. For revegetation, EL based Fenton treatment was most appropriately adopted for soil with native pH >/~ 6.2 in order to obtain a final soil pH >/~ 4.9 subject to the soil buffering capacity.
  5. Extraction of phenanthrene and fluoranthene from contaminated sand using palm kernel and soybean oils
    Von Lau E, Gan S, Ng HK
    J Environ Manage, 2012 Sep 30;107:124-30.
    PMID: 22595079 DOI: 10.1016/j.jenvman.2012.04.029
    Experimental extraction tests are conducted to investigate feasibility of saturated palm kernel oil (PKO) and unsaturated soybean oil (SO) to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sand. The extraction rates and efficiencies for lowly contaminated (LC) and highly contaminated (HC) sands at temperatures of 30 °C and 70 °C are evaluated using empirical first order kinetic dissolution models. In LC sand, the extraction is dominated by the diffusion of PAHs adsorbed onto particle surfaces and the direct dissolution of PAH phase. In HC sand, a rapid diffusion of PAHs adsorbed onto particle surfaces and a direct dissolution of PAH phase occur followed by a slower diffusion of PAHs entrapped within the pores and micropores. Larger diffusion resistance during HC sand extractions results in an average 10.8% reduction in extraction efficiencies compared to LC sand. Increased temperature generally increases the mass transfer rates and extraction efficiencies. Additionally, the physicochemical properties of both oils and PAHs also determine the extent of PAH extraction into oil.
  6. Development and characterisation of novel heterogeneous palm oil mill boiler ash-based catalysts for biodiesel production
    Ho WW, Ng HK, Gan S
    Bioresour Technol, 2012 Dec;125:158-64.
    PMID: 23026328 DOI: 10.1016/j.biortech.2012.08.099
    Novel heterogeneous catalysts from calcium oxide (CaO)/calcined calcium carbonate (CaCO(3)) loaded onto different palm oil mill boiler ashes were synthesised and used in the transesterification of crude palm oil (CPO) with methanol to yield biodiesel. Catalyst preparation parameters including the type of ash support, the weight percentage of CaO and calcined CaCO(3) loadings, as well as the calcination temperature of CaCO(3) were optimised. The catalyst prepared by loading of 15 wt% calcined CaCO(3) at a fixed temperature of 800°C on fly ash exhibited a maximum oil conversion of 94.48%. Thermogravimetric analysis (TGA) revealed that the CaCO(3) was transformed into CaO at 770°C and interacted well with the ash support, whereas rich CaO, Al(2)O(3) and SiO(2) were identified in the composition using X-ray diffraction (XRD). The fine morphology size (<5 μm) and high surface area (1.719 m(2)/g) of the fly ash-based catalyst rendered it the highest catalytic activity.
  7. Distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in surface soils from five different locations in Klang Valley, Malaysia
    Lau EV, Gan S, Ng HK
    Bull Environ Contam Toxicol, 2012 May;88(5):741-6.
    PMID: 22297628 DOI: 10.1007/s00128-012-0527-9
    The concentrations of polycyclic aromatic hydrocarbons (PAHs) in soil samples were measured at five different sites within Klang Valley, Malaysia. The results showed that the total concentrations of the fourteen priority PAHs ranged from 64 to 155 μg/kg. Irrespective of the land use, all the measured soil PAH concentrations in this study were significantly lower than that found in soil samples in temperate regions. The profile of PAHs in the soils was dominated by the LMW PAHs. The PAHs in Klang Valley soils originated from pyrogenic sources, with a combination of petroleum and biomass combustion in vehicles, industries and non-point sources.
  8. Evaluation of solubility of polycyclic aromatic hydrocarbons in ethyl lactate/water versus ethanol/water mixtures for contaminated soil remediation applications
    Yap CL, Gan S, Ng HK
    J Environ Sci (China), 2012;24(6):1064-75.
    PMID: 23505874
    Solubility data of recalcitrant contaminants in cosolvents is essential to determine their potential applications in enhanced soil remediation. The solubilities of phenanthrene, anthracene, fluoranthene and benzo[a]pyrene in ethyl lactate/water and ethanol/water mixtures were measured using equilibrium techniques. The cosolvency powers derived from solubility data were then applied to the model developed from the solvophobic approach to predict the capability of ethyl lactate and ethanol in enhancing the desorption of contaminants from soils. Both ethyl lactate and ethanol cosolvents were shown to be able to enhance the solubilisation of the tested four polycyclic aromatic hydrocarbons by > 4 orders of magnitude above the levels obtained with water alone. However, ethyl lactate demonstrated a greater capacity to enhance PAH solubility than ethanol. The cosolvency powers of ethyl lactate/water system obtained from the end-to-end slope (sigma) and the end-to-half slope (sigma0.5) of the solubilisation curve were 1.0-1.5 and 2.0-2.9 higher than ethanol/water system respectively. In line with this, ethyl lactate/water was demonstrated to enhance the desorption of contaminants from soil by 20%-37% and 18%-61% higher compared to ethanol/water system in low organic content and high organic content soils respectively, with a 2:1 (V/W) ratio of solution:soil and with cosolvent fraction as low as 0.4. With the exception of benzo[a]pyrene, the experimental desorption results agreed fairly with the predicted values, under an applied solution:soil ratio that was enough to hold the capacity of released contaminants.
  9. Fenton based remediation of polycyclic aromatic hydrocarbons-contaminated soils
    Yap CL, Gan S, Ng HK
    Chemosphere, 2011 Jun;83(11):1414-30.
    PMID: 21316731 DOI: 10.1016/j.chemosphere.2011.01.026
    This paper aims to review the applications of Fenton based treatments specifically for polycyclic aromatic hydrocarbons-contaminated soils. An overview of the background and principles of Fenton treatment catalysed by both homogenous (conventional and modified Fenton) and heterogeneous (Fenton-like) catalysts is firstly presented. Laboratory and field soil remediation studies are then discussed in terms of efficiency, kinetics and associated factors. Four main scopes of integrated Fenton treatments, i.e. physical-Fenton, biological-Fenton, electro-Fenton and photo-Fenton are also reviewed in this paper. For each of these integrated remediation technologies, the theoretical background and mechanisms are detailed alongside with achievable removal efficiencies for polycyclic aromatic hydrocarbons in contaminated soils compared to sole Fenton treatment. Finally, the environmental impacts of Fenton based soil treatments are documented and discussed.
  10. Application of vegetable oils in the treatment of polycyclic aromatic hydrocarbons-contaminated soils
    Yap CL, Gan S, Ng HK
    J Hazard Mater, 2010 May 15;177(1-3):28-41.
    PMID: 20006435 DOI: 10.1016/j.jhazmat.2009.11.078
    A brief review is conducted on the application of vegetable oils in the treatment of PAH-contaminated soils. Three main scopes of treatment strategies are discussed in this work including soil washing by oil, integrated oil-biological treatment and integrated oil-non-biological treatment. For each of these, the arguments supporting vegetable oil application, the applied treatment techniques and their efficiencies, associated factors, as well as the feasibility of the techniques are detailed. Additionally, oil regeneration, the environmental impacts of oil residues in soil and comparison with other commonly employed techniques are also discussed.
  11. Remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs)
    Gan S, Lau EV, Ng HK
    J Hazard Mater, 2009 Dec 30;172(2-3):532-49.
    PMID: 19700241 DOI: 10.1016/j.jhazmat.2009.07.118
    Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic micropollutants which are resistant to environmental degradation due to their highly hydrophobic nature. Concerns over their adverse health effects have resulted in extensive studies on the remediation of soils contaminated with PAHs. This paper aims to provide a review of the remediation technologies specifically for PAH-contaminated soils. The technologies discussed here include solvent extraction, bioremediation, phytoremediation, chemical oxidation, photocatalytic degradation, electrokinetic remediation, thermal treatment and integrated remediation technologies. For each of these, the theories are discussed in conjunction with comparative evaluation of studies reported in the specialised literature.
  12. Fulltext Extraction techniques for polycyclic aromatic hydrocarbons in soils
    Lau EV, Gan S, Ng HK
    Int J Anal Chem, 2010;2010:398381.
    PMID: 20396670 DOI: 10.1155/2010/398381
    This paper aims to provide a review of the analytical extraction techniques for polycyclic aromatic hydrocarbons (PAHs) in soils. The extraction technologies described here include Soxhlet extraction, ultrasonic and mechanical agitation, accelerated solvent extraction, supercritical and subcritical fluid extraction, microwave-assisted extraction, solid phase extraction and microextraction, thermal desorption and flash pyrolysis, as well as fluidised-bed extraction. The influencing factors in the extraction of PAHs from soil such as temperature, type of solvent, soil moisture, and other soil characteristics are also discussed. The paper concludes with a review of the models used to describe the kinetics of PAH desorption from soils during solvent extraction.
  13. Feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate-based Fenton treatment via parametric and kinetic studies
    Yap CL, Gan S, Ng HK
    Environ Sci Pollut Res Int, 2015 Jan;22(1):329-42.
    PMID: 25065478 DOI: 10.1007/s11356-014-3199-7
    This study focuses on the feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate (EL)-based Fenton treatment via a combination of parametric and kinetic studies. An optimised operating condition was observed at 66.7 M H2O2 with H2O2/Fe(2+) of 40:1 for low soil organic carbon (SOC) content and mildly acidic soil (pH 6.2), and 10:1 for high SOC and very acidic soil (pH 4.4) with no soil pH adjustment. The desorption kinetic was only mildly shifted from single equilibrium to dual equilibrium of the first-order kinetic model upon ageing. Pretreatment with EL fc = 0.60 greatly reduced the mass transfer coefficient especially for the slow desorbed fraction (kslow) of high molecular weight (HMW) PAHs, largely contributed by the concentration gradient created by EL-enhanced solubility. As the major desorption obstacle was almost fully overcome by the pretreatment, the pseudo-first-order kinetic reaction rate constant of PAHs degradation of aged soils was statistically discernible from that of freshly contaminated soils but slightly reduced in high SOC and high acidity soil. Stabilisation of H2O2 by EL addition in combination with reduced Fe(2+) catalyst were able to slow the decomposition rate of H2O2 even at higher soil pH.
  14. Extraction agents for the removal of polycyclic aromatic hydrocarbons (PAHs) from soil in soil washing technologies
    Lau EV, Gan S, Ng HK, Poh PE
    Environ Pollut, 2014 Jan;184:640-9.
    PMID: 24100092 DOI: 10.1016/j.envpol.2013.09.010
    Polycyclic aromatic hydrocarbons (PAHs) in soil have been recognised as a serious health and environmental issue due to their carcinogenic, mutagenic and teratogenic properties. One of the commonly employed soil remediation techniques to clean up such contamination is soil washing or solvent extraction. The main factor which governs the efficiency of this process is the solubility of PAHs in the extraction agent. Past field-scale soil washing treatments for PAH-contaminated soil have mainly employed organic solvents or water which is either toxic and costly or inefficient in removing higher molecular weight PAHs. Thus, the present article aims to provide a review and discussion of the alternative extraction agents that have been studied, including surfactants, biosurfactants, microemulsions, natural surfactants, cyclodextrins, vegetable oil and solution with solid phase particles. These extraction agents have been found to remove PAHs from soil at percentages ranging from 47 to 100% for various PAHs.
  15. Gynura procumbens causes vasodilation by inhibiting angiotensin II and enhancing bradykinin actions
    Poh TF, Ng HK, Hoe SZ, Lam SK
    J Cardiovasc Pharmacol, 2013 May;61(5):378-84.
    PMID: 23328388 DOI: 10.1097/FJC.0b013e31828685b3
    Previous studies showed that Gynura procumbens reduced blood pressure by blocking calcium channels and inhibiting the angiotensin-converting enzyme activity. The present experiments were to further explore the effects and mechanisms of a purer aqueous fraction (FA-I) of G. procumbens on angiotensin I (Ang I)-induced and angiotensin II (Ang II)-induced contraction of aortic rings and also on the bradykinin (BK) effect on cardiovascular system. Rat aortic rings suspended in organ chambers were used to investigate the vascular reactivity of FA-I. Effect of FA-I on BK was studied by in vitro and in vivo methods. Results show that FA-I significantly (P < 0.05) decreased the contraction evoked by Ang I and Ang II. In the presence of indomethacin (10 µM) or N-nitro-L-arginine methyl ester (0.1 µM), the inhibitory effect of FA-I on Ang II-induced contraction of aortic rings was reduced. Besides, FA-I potentiated the vasorelaxant effect and enhanced the blood pressure-lowering effect of BK. In conclusion, FA-I reduced the contraction evoked by Ang II probably via the endothelium-dependent pathways, which involve activation of the release of nitric oxide and prostaglandins. The inhibition of angiotensin-converting enzyme activity by FA-I may contribute to the potentiation of the effects of BK on cardiovascular system.
  16. Fulltext Antiphospholipid syndrome in lupus retinopathy
    Ng HK, Chong MF, Azhany Y, Zunaina E
    Clin Ophthalmol, 2014;8:2359-63.
    PMID: 25473262 DOI: 10.2147/OPTH.S71712
    Systemic lupus erythematosus (SLE) is a chronic, multisystem, autoimmune disease that can affect any part of the human body including the eyes. Common blinding ocular manifestations include central retinal artery occlusion (CRAO), central retinal vein occlusion (CRVO), severe vaso-occlusive retinopathy, and optic nerve involvement. Antiphospholipid syndrome (APS) in lupus is usually associated with large vessel occlusions and needs prompt treatment with anticoagulant. We are reporting two cases of APS in SLE patients that presented with CRVO (case 1) and vaso-occlusive lupus retinopathy (case 2). Both cases were positive for antiphospholipid antibody (APA) and were treated with immunosuppression, anticoagulant, and laser treatment. Thus, screening for APA is vital in SLE patients with lupus retinopathy, as prompt treatment with anticoagulants is important to prevent further vascular thrombosis, which worsens the visual prognosis.
    Study site: Ophthalmology clinic, Hospital Raja Permaisuri Bainun, Ipoh, Perak, Malaysia
  17. Fulltext Current status of Helicobacter pylori resistance to Clarithromycin and Levofloxacin in Malaysia-findings from a molecular based study
    Puah SM, Goh KL, Ng HK, Chua KH
    PeerJ, 2021;9:e11518.
    PMID: 34178444 DOI: 10.7717/peerj.11518
    Background: Resistance to clarithromycin and levofloxacin in Helicobacter pylori which resulted in treatment failures has become a major challenge for physicians worldwide. The resistance is mainly mediated by mutations in a specific domain of the 23S rRNA, gyrA and gyrB genes for clarithromycin and levofloxacin respectively. Hence in this study, we aimed to investigate the current status of H. pylori resistance in our hospital to these two antibiotics based on the molecular approach.

    Materials and Methods: Gastric biopsy samples were obtained from treatment-naïve patients. Bacterial genomic DNA was extracted using a commercial kit and continued with DNA amplification using polymerase chain reaction (PCR) with specific primers. The PCR amplicons were subjected to sequencing on 23S rRNA gene targeting nucleotide positions at 2,146, 2,147, 2,186 and amino acids at gyrA positions 87 and 91 and gyrB positions 436, 438, 481, 484 to investigate the possible mutations or polymorphisms of genes that lead to clarithromycin and levofloxacin resistance respectively.

    Results: Sixty-one urease-positive gastric biopsy samples were studied. The findings revealed the primary resistance rates to clarithromycin was 14.8% and to levofloxacin was 3.3% in our current scenario based on detection of reported resistance-related mutations of A2147G and D91N in 23S rRNA and gyrA genes, respectively. Interestingly, we found a high rate of silent mutations of the gyrA codon 87Asn (32.8%, 20/61) and two polymorphisms of the gyrB D481E (16.4%, 10/61) and R484K (21.3%, 13/61). The role of these polymorphisms in gyrB remained to be elucidated whether the levels of levofloxacin resistance are related to the position/amino acid.

    Conclusion: The primary resistance rate of H. pylori to clarithromycin has increased compared to the previous report in Malaysia. Therefore, molecular screening could aid and is important for the selection of antibiotics for H. pylori eradication therapies.

  18. Fulltext Bioethics Education in the Medical Programme among Malaysian Medical Schools: Where Are We Now?
    Sim JH, Ngan OMY, Ng HK
    J Med Educ Curric Dev, 2019 12 02;6:2382120519883887.
    PMID: 31832540 DOI: 10.1177/2382120519883887
    Introduction: A global trend in medical education is the inclusion of bioethics teaching in medical programme. The objective of this article is to describe the current state of bioethics education in the medical programme among Malaysian medical schools.

    Method: A national survey was conducted among Malaysian medical schools between January and March 2019. One representative from each medical school was invited to respond to the survey. Respondents were faculty members involved in teaching and assessment of bioethics in their medical schools, or/and in developing and coordinating bioethics curriculum. Descriptive statistics were reported.

    Findings: Out of 30 medical schools, 11 completed and returned the survey (overall response rate = 36.7%). Of these 11 schools, 6/10 (60%) were from public institutions while 5/20 (25%) were from private institutions. All except 1 school implemented a formal bioethics curriculum. A wide range of bioethics topics are currently taught in the medical programme. The majority involved in teaching bioethics were health care professionals (mainly clinicians), followed by lawyers. Lecture and attendance, respectively, are the most common teaching and assessment method. Major barriers to the implementation of bioethics education included limited qualified teaching staff (6/11 = 54.5%), no established curriculum to follow (5/11 = 45.5%), limited financial resources to hire qualified staff (4/11 = 36.4%), and no consensus among faculty members (4/11 = 36.4%).

    Conclusion: Bioethics education in Malaysia is relatively new and mostly limited by a shortage of scholars in bioethics. National support and institutional collaboration in providing bioethics training is the key to enhance the quality of bioethics education.

  19. Evaluation of ethyl lactate as solvent in Fenton oxidation for the remediation of total petroleum hydrocarbon (TPH)-contaminated soil
    Jalilian Ahmadkalaei SP, Gan S, Ng HK, Abdul Talib S
    Environ Sci Pollut Res Int, 2017 Jul;24(21):17779-17789.
    PMID: 28602003 DOI: 10.1007/s11356-017-9382-x
    Due to the health and environmental risks posed by the presence of petroleum-contaminated areas around the world, remediation of petroleum-contaminated soil has drawn much attention from researchers. Combining Fenton reaction with a solvent has been proposed as a novel way to remediate contaminated soils. In this study, a green solvent, ethyl lactate (EL), has been used in conjunction with Fenton's reagents for the remediation of diesel-contaminated soil. The main aim of this research is to determine how the addition of EL affects Fenton reaction for the destruction of total petroleum hydrocarbons (TPHs) within the diesel range. Specifically, the effects of different parameters, including liquid phase volume-to-soil weight (L/S) ratio, hydrogen peroxide (H2O2) concentration and EL% on the removal efficiency, have been studied in batch experiments. The results showed that an increase in H2O2 resulted in an increase in removal efficiency of TPH from 68.41% at H2O2 = 0.1 M to 90.21% at H2O2 = 2 M. The lowest L/S, i.e. L/S = 1, had the highest TPH removal efficiency of 85.77%. An increase in EL% up to 10% increased the removal efficiency to 96.74% for TPH, and with further increase in EL%, the removal efficiency of TPH decreased to 89.6%. EL with an optimum value of 10% was found to be best for TPH removal in EL-based Fenton reaction. The power law and pseudo-first order equations fitted well to the experimental kinetic data of Fenton reactions.
  20. Investigation of ethyl lactate as a green solvent for desorption of total petroleum hydrocarbons (TPH) from contaminated soil
    Jalilian Ahmadkalaei SP, Gan S, Ng HK, Abdul Talib S
    Environ Sci Pollut Res Int, 2016 Nov;23(21):22008-22018.
    PMID: 27539472
    Treatment of oil-contaminated soil is a major environmental concern worldwide. The aim of this study is to examine the applicability of a green solvent, ethyl lactate (EL), in desorption of diesel aliphatic fraction within total petroleum hydrocarbons (TPH) in contaminated soil and to determine the associated desorption kinetics. Batch desorption experiments were carried out on artificially contaminated soil at different EL solvent percentages (%). In analysing the diesel range of TPH, TPH was divided into three fractions and the effect of solvent extraction on each fraction was examined. The experimental results demonstrated that EL has a high and fast desorbing power. Pseudo-second order rate equation described the experimental desorption kinetics data well with correlation coefficient values, R (2), between 0.9219 and 0.9999. The effects of EL percentage, initial contamination level of soil and liquid to solid ratio (L/S (v/w)) on initial desorption rate have also been evaluated. The effective desorption performance of ethyl lactate shows its potential as a removal agent for remediation of TPH-contaminated soil worldwide.
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