Displaying publications 181 - 200 of 242 in total

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  1. Phenolic water pollutants in a Malaysian River basin
    Abdullah P, Nainggolan H
    Environ Monit Assess, 1991 Oct;19(1-3):423-31.
    PMID: 24233958 DOI: 10.1007/BF00401330
    Phenolic chemicals with their very low taste and odour thresholds, high persistence and toxicity, are of growing concern as water pollutants. The compounds are known to exist in raw water as well as in treated water. The level of phenolic priority pollutants in water within the catchment area of the Linggi River Treatment Plant in Negeri Sembilan, Malaysia, which includes the Linggi river basin, was monitored. The 4-aminoantipyrin colourimetric method was used to determine total phenols whereas capillary column gas chromatography was used to determine the individual compounds. The results show that at most sampling stations, particularly those within the Seremban municipality, the level of phenols was found to exceed the recommended Malaysian standard of 2.0 μg/L(-1) for raw water. This is seen as the direct impact of industrial and urbanization of the area and clearly indicates the unhealthy state of the Linggi river. The results also indicate the need to improve the water quality if the river is going to be used as a source of raw water.
    Matched MeSH terms: Environmental Pollutants
  2. Management and control of pollution in Inner Johore Strait
    Koh HL, Lim PE, Midun Z
    Environ Monit Assess, 1991 Oct;19(1-3):349-59.
    PMID: 24233952 DOI: 10.1007/BF00401324
    Coastal waters in South Johore, Malaysia are polluted to various degrees. The major pollution sources are domestric wastes from human settlements, agro-based wastes from palm oil mills and rubber processing factories, industrial effluents from industrial estates and discharges from animal farms. These pollution problems have adversely affected resources such as fisheries, recreational potential as well as the general aesthetic quality of the coastal environment particularly the Inner Johore Strait. Hence proper management and control measures are urgently needed to protect and further enhance the water quality to ensure environmentally sustainable development. This study examines various management options to control the pollution in the Inner Johore Strait. The options involve partial opening as well as complete removal of the Causeway to improve the tidal flow for more effective dilution and dispersion of pollutants. Computer simulation models are used to assess the impacts of the proposed options.
    Matched MeSH terms: Environmental Pollutants
  3. Fulltext Effective production of keratinase by gellan gum-immobilised Alcaligenes sp. AQ05-001 using heavy metal-free and polluted feather wastes as substrates
    Yusuf I, Ahmad SA, Phang LY, Yasid NA, Shukor MY
    3 Biotech, 2019 Jan;9(1):32.
    PMID: 30622870 DOI: 10.1007/s13205-018-1555-x
    The ability of gellan gum-immobilised cells of the heavy metal-tolerant bacterium Alcaligenes sp. AQ05-001 to utilise both heavy metal-free and heavy metal-polluted feathers (HMPFs) as substrates to produce keratinase enzyme was studied. Optimisation of the media pH, incubation temperature and immobilisation parameters (bead size, bead number, gellan gum concentration) was determined for the best possible production of keratinase using the one-factor-at-a-time technique. The results showed that the immobilised cells could tolerate a broader range of heavy metal concentrations and produced higher keratinase activity at a gellan gum concentration of 0.8% (w/v), a bead size of 3 mm, bead number of 250, pH of 8 and temperature of 30 °C. The entrapped bacterium was used repeatedly for ten cycles to produce keratinase using feathers polluted with 25 ppm of Co, Cu and Ag as substrates without the need for desorption. However, its inability to tolerate/utilise feathers polluted with Hg, Pb, and Zn above 5 ppm, and Ag and Cd above 10 ppm resulted in a considerable decrease in keratinase production. Furthermore, the immobilised cells could retain approximately 95% of their keratinase production capacity when 5 ppm of Co, Cu, and Ag, and 10 ppm of As and Cd were used to pollute feathers. When the feathers containing a mixture of Ag, Co, and Cu at 25 ppm each and Hg, Ni, Pb, and Zn at 5 ppm each were used as substrates, the immobilised cells maintained their operational stability and biological activity (keratinase production) at the end of 3rd and 4th cycles, respectively. The study indicates that HMPF can be effectively utilised as a substrate by the immobilised-cell system of Alcaligenes sp. AQ05-001 for the semi-continuous production of keratinase enzyme.
    Matched MeSH terms: Environmental Pollutants
  4. Trend and status of air quality at three different monitoring stations in the Klang Valley, Malaysia
    Azmi SZ, Latif MT, Ismail AS, Juneng L, Jemain AA
    Air Qual Atmos Health, 2010 Mar;3(1):53-64.
    PMID: 20376168
    Over the last decades, the development of the Klang Valley (Malaysia), as an urban commercial and industrial area, has elevated the risk of atmospheric pollutions. There are several significant sources of air pollutants which vary depending on the background of the location they originate from. The aim of this study is to determine the trend and status of air quality and their correlation with the meteorological factors at different air quality monitoring stations in the Klang Valley. The data of five major air pollutants (PM(10), CO, SO(2), O(3), NO(2)) were recorded at the Alam Sekitar Sdn Bhd (ASMA) monitoring stations in the Klang Valley, namely Petaling Jaya (S1), Shah Alam (S2) and Gombak (S3). The data from these three stations were compared with the data recorded at Jerantut, Pahang (B), a background station established by the Malaysian Department of Environment. Results show that the concentrations of CO, NO(2) and SO(2) are higher at Petaling Jaya (S1) which is due to influence of heavy traffic. The concentrations of PM(10) and O(3,) however, are predominantly related to regional tropical factors, such as the influence of biomass burning and of ultra violet radiation from sunlight. They can, though, also be influenced by local sources. There are relatively stronger inter-pollutant correlations at the stations of Gombak and Shah Alam, and the results also suggest that heavy traffic flow induces high concentrations of PM(10), CO, NO(2) and SO(2) at the three sampling stations. Additionally, meteorological factors, particularly the ambient temperature and wind speed, may influence the concentration of PM(10) in the atmosphere.
    Matched MeSH terms: Environmental Pollutants
  5. Surfactant-functionalised magnetic ferum oxide coupled with high performance liquid chromatography for the extraction of phenol
    Beh SY, Md Saleh N, Asman S
    Anal Methods, 2021 02 07;13(5):607-619.
    PMID: 33480366 DOI: 10.1039/d0ay02166k
    The usage of phenols in the marketplace has been increasing tremendously, which has raised concerns about their toxicity and potential effect as emerging pollutants. Phenol's structure has closely bonded phenyl and hydroxy groups, thereby making its functional characteristics closely similar to that of alcohol. As a result, phenol is used as a base compound for commercial home-based products. Hence, a simple and efficient procedure is required to determine the low concentration of phenols in environmental water samples. In this research, a method of combining magnetic nanoparticles (MNPs) with surfactant Sylgard 309 was developed to overcome the drawbacks in the classical extraction methods. In addition, this developed method improved the performance of extraction when MNPs and the surfactant Sylgard 309 were used separately, as reported in the previous research. This MNP-Sylgard 309 was synthesised by the coprecipitation method and attracts phenolic compounds in environmental water samples. Response surface methodology was used to study the parameters and responses in order to obtain an optimised condition using MNP-Sylgard 309. The parameters included the effect of pH, extraction time, and concentration of the analyte. Meanwhile, the responses measured were the peak area of the chromatogram and the percentage recovery. From this study, the results of the optimum conditions for extraction using MNP-Sylgard 309 were pH 7, extraction time of 20 min, and analyte concentration of 10.0 μg mL-1. Under the optimized conditions, MNP-Sylgard 309 showed a low limit of detection of 0.665 μg mL-1 and the limit of quantification was about 2.219 μg mL-1. MNP-Sylgard 309 was successfully applied on environmental water samples such as lake and river water. High recovery (76.23%-110.23%) was obtained.
    Matched MeSH terms: Environmental Pollutants
  6. Fulltext Data for the industrial and municipal environmental wastes hazard contaminants assessment with integration of RES2D techniques and Oasis Montaj software
    Arifin MH, Kayode JS, Ismail KI, Abdullah M, Embrandiri A, Nazer SM, et al.
    Data Brief, 2020 Dec;33:106595.
    PMID: 33318980 DOI: 10.1016/j.dib.2020.106595
    Industrial, and municipal wastes are part of the main sources of environmental hazards as well as groundwater and surface water pollutions. If not well composed, treated, and safely disposed, it could permeate through the subsurface lithologies by reaching down to the underground water aquifers, particularly in zones of unprotected aquifer units. Pollutants, most especially the landfills leachates that encompassed organic contaminants, ammonia, nitrates, total nitrogen, suspended solids, heavy metals and soluble inorganic salts, i.e., soluble nitrogen, sulphur compound, sulphate and chlorides, could posed undesirable environmental impacts due to inappropriate disposals that may give rise to gaseous fumes and leachate formations. An electrical resistivity geophysical technique utilizing the RES2D no-invasive, cost-effective and rapid method of data collection was integrated with the 3D Oasis Montaj software to approximate the volume of the generated rectangular prism model of the contaminants delineated from mixtures of the industrial, and municipal wastes plumes to be 312,000 m 3.
    Matched MeSH terms: Environmental Pollutants
  7. Ancillary palm oil fuel ash (POFA) in sequencing batch reactor for enhancing recalcitrant pollutants removal from domestic wastewater
    Lyn CW, Bashir MJ, Wong LY, Lim JW, Sethupathi S, Ng CA
    Chemosphere, 2020 Nov 25.
    PMID: 33276996 DOI: 10.1016/j.chemosphere.2020.129050
    Domestic wastewater has been generated massively along with rapid growth of population and economic. Biological treatment using sequencing batch reactor (SBR) augmented with palm oil fuel ash (POFA) was investigated for the first time. The performance of POFA in enhancing biological treatment of wastewater has not been tested. The porosity property of POFA can improve SBR efficiency by promoting growth of mixed liquor suspended solids (MLSS) and formation of larger flocs for settling and facilitating attachment of microorganisms and pollutants onto POFA surfaces. The properties of POFA were tested to identify morphological properties, particle size, surface area, chemical compositions. Four SBRs, namely SBR1, SBR2, SBR3 and SBR4 were provided with aeration rate of 1, 2, 3 and 4 L/min, respectively. Each reactor was augmented with different dosages of POFA. Optimum aeration rate and POFA concentration were identified by the performance of SBRs in removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and colour from domestic wastewater. The results showed the most efficient COD (97.8%), NH3-N (99.4%) and colour (98.8%) removals were achieved at optimum POFA concentration of 4 g/L in SBR and aeration rate of 1 L/min. The study also found that higher aeration rate would contribute to the smaller specific size of flocs and decrease the pollutant removal efficiency.
    Matched MeSH terms: Environmental Pollutants
  8. Water Quality Modelling for River Activities Management: Example from a Low- and Middle-Income Country
    Zahidi I, Wilson G, Brown K, Hou FKK
    J Health Pollut, 2020 Dec;10(28):201207.
    PMID: 33324504 DOI: 10.5696/2156-9614-10.28.201207
    Background: Rivers are susceptible to pollution and water pollution is a growing problem in low- and middle-income countries (LMIC) with rapid development and minimal environmental protections. There are universal pollutant threshold values, but they are not directly linked to river activities such as sand mining and aquaculture. Water quality modelling can support assessments of river pollution and provide information on this important environmental issue.

    Objectives: The objective of the present study was to demonstrate water quality modelling methodology in reviewing existing policies for Malaysian river catchments based on an example case study.

    Methods: The MIKE 11 software developed by the Danish Hydraulic Institute was used to model the main pollutant point sources within the study area - sand mining and aquaculture. Water quality data were obtained for six river stations from 2000 to 2015. All sand mining and aquaculture locations and approximate production capacities were quantified by ground survey. Modelling of the sand washing effluents was undertaken with the advection-dispersion module due to the nature of the fine sediment. Modelling of the fates of aquaculture deposits required both advection-dispersion and Danish Hydraulic Institute ECO Lab modules to simulate the detailed interactions between water quality determinants.

    Results: According to the Malaysian standard, biochemical oxygen command (BOD) and ammonium (NH4) parameters fell under Class IV at most of the river reaches, while the dissolved oxygen (DO) parameter varied between Classes II to IV. Total suspended solids (TSS) fell within Classes IV to V along the mid river reaches of the catchment.

    Discussion: Comparison between corresponding constituents and locations showed that the water quality model reproduced the long-term duration exceedance for the main body of the curves. However, the water quality model underestimated the infrequent high concentration observations. A standard effluent disposal was proposed for the development of legislation and regulations by authorities in the district that could be replicated for other similar catchments.

    Conclusions: Modelling pollutants enables observation of trends over the years and the percentage of time a certain class is exceeded for each individual pollutant. The catchment did not meet Class II requirements and may not be able to reach Class I without extensive improvements in the quality and reducing the quantity of both point and non-point effluent sources within the catchment.

    Competing Interests: The authors declare no competing financial interests.

    Matched MeSH terms: Environmental Pollutants
  9. Organic-Inorganic Hybrid Nanoflower Production and Analytical Utilization: Fundamental to Cutting-Edge Technologies
    Subramani IG, Perumal V, Gopinath SCB, Fhan KS, Mohamed NM
    Crit Rev Anal Chem, 2021 Mar 11.
    PMID: 33691533 DOI: 10.1080/10408347.2021.1889962
    Over the past decade, science has experienced a growing rise in nanotechnology with ground-breaking contributions. Through various laborious technologies, nanomaterials with different architectures from 0 D to 3 D have been synthesized. However, the 3 D flower-like organic-inorganic hybrid nanomaterial with the most direct one-pot green synthesis method has attracted widespread attention and instantly become research hotspot since its first allusion in 2012. Mild synthesis procedure, high surface-to-volume ratio, enhanced enzymatic activity and stability are the main factor for its rapid development. However, its lower mechanical strength, difficulties in recovery from the reaction system, lower loading capacity, poor reusability and accessibility of enzymes are fatal, which hinders its wide application in industry. This review first discusses the selection of non-enzymatic biomolecules for the synthesis of hybrid nanoflowers followed by the innovative advancements made in organic-inorganic hybrid nanoflowers to overcome aforementioned issues and to enhance their extensive downstream applications in transduction technologies. Besides, the role of hybrid nanoflower has been successfully utilized in many fields including, water remediation, biocatalyst, pollutant adsorption and decolourization, nanoreactor, biosensing, cellular uptake and others, accompanied with several quantification technologies, such as ELISA, electrochemical, surface plasmon resonance (SPR), colorimetric, and fluorescence were comprehensively reviewed.
    Matched MeSH terms: Environmental Pollutants
  10. Fulltext High Sensitivity Microfiber Interferometer Sensor in Aqueous Solution
    Girei SH, Lim HN, Ahmad MZ, Mahdi MA, Md Zain AR, Yaacob MH
    Sensors (Basel), 2020 Aug 21;20(17).
    PMID: 32825539 DOI: 10.3390/s20174713
    The need for environmental protection and water pollution control has led to the development of different sensors for determining many kinds of pollutants in water. Ammonia nitrogen presence is an important indicator of water quality in environmental monitoring applications. In this paper, a high sensitivity sensor for monitoring ammonia nitrogen concentration in water using a tapered microfiber interferometer (MFI) as a sensor platform and a broad supercontinuum laser as the light source is realized. The MFI is fabricated to the waist diameter of 8 µm producing a strong interference pattern due to the coupling of the fundamental mode with the cladding mode. The MFI sensor is investigated for a low concentration of ammonia nitrogen in water in the wide wavelength range from 1500-1800 nm with a high-power signal provided by the supercontinuum source. The broad source allows optical sensing characteristics of the MFI to be evaluated at four different wavelengths (1505, 1605, 1705, and 1785 nm) upon exposure towards various ammonia nitrogen concentrations. The highest sensitivity of 0.099 nm/ppm that indicates the wavelength shift is observed at 1785 nm operating wavelength. The response is linear in the ammonia nitrogen range of 5-30 ppm with the best measurement resolution calculated to be 0.5 ppm. The low concentration ammonia nitrogen detected by the MFI in the unique infrared region reveals the potential application of this optical fiber-based sensor for rivers and drinking water monitoring.
    Matched MeSH terms: Environmental Pollutants
  11. Recycling of aquaculture wastewater and sediment for sustainable corn and water spinach production
    Van Tung T, Tran QB, Phuong Thao NT, Vi LQ, Hieu TT, Le S, et al.
    Chemosphere, 2020 Dec 15;268:129329.
    PMID: 33360937 DOI: 10.1016/j.chemosphere.2020.129329
    This study develops a method to reuse aquaculture wastewater and sediment from a catfish pond in order to increase agricultural productivity and protect the environment. Material flow analysis (MFA) is a central concept of this study that involves collecting catfish pond wastewater (CPW) and reusing it to irrigate five water spinach (Ipomoea aquatic) ponds before discharging it into a river. Typically, catfish pond sediment (CPS) was collected and composted to produce organic fertilizer for cornfields. The results revealed that pollutant removal efficiency of wastewater from CPW (by using water spinach) were total organic carbon (TOC) = 38.78%, nitrogen (N) = 27.07%, phosphorous (P) = 58.42%, and potassium (K) = 28.64%. By adding 20 tons of CPS compost per hectare of the cornfield, the corn yield boosted 15% compared to the control field. In addition, the water spinach grew and developed well in the medium of wastewater from the fish pond. Altogether, the results illustrate that catfish pond wastewater and sediment can act as organic fertilizers for crops meanwhile reduce environmental pollution from its reuse.
    Matched MeSH terms: Environmental Pollutants
  12. Fulltext DISPERSIVE LIQUID-LIQUID MICROEXTRACTION FOR THE EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBONS IN APPLE JUICE
    LIANG SUN TAN, SAW HONG LOH
    UMT Journal of Undergraduate Research, 2020;2(2):15-22.
    MyJurnal
    Polycyclic aromatic hydrocarbons (PAHs) are hazardous and persistent organic pollutants that usually exist at low concentrations in the environment. In this study, dispersive liquid-liquid microextraction (DLLME) technique coupled with high performance liquid chromatography-fluorescence detection (HPLC-FD) was optimized for the analysis of selected PAHs, namely phenanthrene (PHE), fluoranthene (FLA) and benzo[a]pyrene (BaP) in apple juice. Under the optimal extraction conditions (the mixture of 200 µL of acetone and 50 µL of 1-octanol was applied to extract the selected PAHs for 1 min), the DLLME-HPLC-FD showed excellent linearity over the concentration range of 5 to 200 µg/L for both PHE and FLA, and 0.01 to 5 µg/L for BaP with correlation coefficients, r ≥ 0.9956. The method offered ultra-trace detection of selected PAHs in the range of 0.002 to 0.5 µg/L, and negligible matrix effects in determining selected PAHs with relative recovery average within the range of 92.6 to 109.6% in apple juice. The advantages of applying this method for the extraction of PAHs include rapidity, simple operation, as well as small consumption of organic extraction solvent, which is beneficial for routine analysis.
    Matched MeSH terms: Environmental Pollutants
  13. Fulltext PRELIMINARY ASSESSMENT OF THE DISTRIBUTION OF PM2.5-BOUND POLYCYCLIC AROMATIC HYDROCARBONS IN PRIMARY SCHOOL ENVIRONMENTS IN KUALA LUMPUR
    MOHAMAD FIRDAUS ISMAIL, MUHAMMAD FAIS FADZIL, NORHAYATI MOHD TAHIR, NORHAYATI MOHD TAHIR, MOHD TALIB LATIF, NOORLIN MOHAMAD
    UMT Journal of Undergraduate Research, 2019;1(2):51-58.
    MyJurnal
    Fine particulate matter (aerodynamic diameter ≤2.5 μm) (PM2.5) has become a major concern because it can adsorb chemicals e.g. polycyclic aromatic hydrocarbons (PAHs) onto its surface. Although PAHs are priority pollutants that can cause adverse health effect, there is still limited information concerning indoor exposures to PAHs in Malaysia. This study aimed to characterise the distribution of PAHs bounded to PM2.5in primary school environments. Indoor and outdoor PM2.5 were collected between May and July 2017 using low volume samplers (LVS) at three public primary schools in the Federal Territory of Kuala Lumpur. PAHs were extracted by ultrasonic extraction with Dichloromethane: n-Hexane (1:1, v/v) as the extraction solvent and analysed using gas chromatography coupled with mass spectrometer (GC-MS). Based on the results, the average total concentration of PAHs (∑PAHs) ranged from 3.8 to 10.1 ng m-3and 1.6 to 8.0 ng m-3for outdoors and indoors, respectively. PAHs in PM2.5samples indicated the potential contribution of combustion at high temperature and indoor sources and the infiltration of outdoor PAHs were the important sources for outdoor and indoor, respectively. In addition, the diagnostic ratio analysis showed that vehicular emissions were the most predominant sources of PAHs in school environments.
    Matched MeSH terms: Environmental Pollutants
  14. Fulltext Environmental and socioeconomic impacts of pipeline transport interdiction in Niger Delta, Nigeria
    Umar HA, Abdul Khanan MF, Ogbonnaya C, Shiru MS, Ahmad A, Baba AI
    Heliyon, 2021 May;7(5):e06999.
    PMID: 34027190 DOI: 10.1016/j.heliyon.2021.e06999
    Over the years, pipelines have been the most economic medium for transporting crude oil to production and distribution facilities in the Niger Delta area of Nigeria. However, damages to the pipelines in this area by interdiction have hampered the continuous flow of crude oil to the facilities. Consequently, the revenue of the government dwindles, and the environment is severely degraded. This study assesses the economic and environmental impacts of pipeline interdiction in the Niger Delta region. Data from National oil spills detection and response agency, Nigeria is used to map spatial distribution of oil spills using Kernel Density Estimation with Geographic Information System. Literature was assessed to synthesize the historical, socioeconomic, and environmental impacts of oil spills and pipeline interdiction. Soil samples were collected from study area to determine the types of hydrocarbon pollutants and their concentrations in comparison with uncontaminated sites in the area. Results show that the range of concentrations of total petroleum hydrocarbon (TPH) for the impacted soil (IMP) was 17.27-58.36 mg/kg; remediated soil (RS) was 11.73-50.78 mg/kg which were higher than the concentrations of 0.68 mg/kg in the control samples (CS). Polycyclic aromatic hydrocarbons (PAH) concentrations were in the range of 0.43-77.54 mg/kg for IMP, 0.42-10.65 mg/kg for RS, against CS value of 0.49 mg/kg while BTEX ranged between 0.02 - 0.38 mg/kg for IMP, 0.01-2.7 for RS against CS value of 0.01. The values of the PAH were higher than the limits of the Department of Petroleum Resources, Nigeria. This study also revealed that pipeline interdiction has affected the livelihood of the inhabitants of the study area and the revenue of the Nigerian government. The major hotspots for oil spills in the Niger Delta region are Bayelsa, Rivers and Delta states.
    Matched MeSH terms: Environmental Pollutants
  15. A review on effective removal of emerging contaminants from aquatic systems: Current trends and scope for further research
    Rathi BS, Kumar PS, Show PL
    J Hazard Mater, 2021 05 05;409:124413.
    PMID: 33183841 DOI: 10.1016/j.jhazmat.2020.124413
    Wastewater is water that has already been contaminated by domestic, industrial and commercial activity that needs to be treated before it could be discharged into some other water bodies to avoid even more groundwater contamination supplies. It consists of various contaminants like heavy metals, organic pollutants, inorganic pollutants and Emerging contaminants. Research has been doing on all types of contaminates more than a decade, but this emerging contaminants is the contaminants which arises mostly from pharmaceuticals, personal care products, hormones and fertilizer industries. The majority of emerging contaminants did not have standardized guidelines, but may have adverse effects on human and marine organisms, even at smaller concentrations. Typically, extremely low doses of emerging contaminants are found in the marine environment and cause a potential risk to the aquatic animals living there. When contaminants emerge in the marine world, they are potentially toxic and pose many risks to the health of both man and livestock. The aim of this article is to review the Emerging contaminate sources, detection methods and treatment methods. The purpose of this study is to consider the adsorption as a beneficial treatment of emerging contaminants also advanced and cost effective emerging contaminates treatment methods.
    Matched MeSH terms: Environmental Pollutants
  16. Molecular docking and molecular dynamics simulation of Bacillus thuringiensis dehalogenase against haloacids, haloacetates and chlorpyrifos
    Oyewusi HA, Huyop F, Wahab RA
    J Biomol Struct Dyn, 2020 Oct 23.
    PMID: 33094694 DOI: 10.1080/07391102.2020.1835727
    The high dependency and surplus use of agrochemical products have liberated enormous quantities of toxic halogenated pollutants into the environment and threaten the well-being of humankind. Herein, this study performed molecular docking, molecular dynamic (MD) simulations, molecular mechanics-Poisson Boltzmann Surface Area (MM-PBSA) calculations on the DehH2 from Bacillus thuringiensis, to identify the order of which the enzyme degrades different substrates, haloacids, haloacetate and chlorpyrifos. The study discovered that the DehH2 favored the degradation of haloacids and haloacetates (-3.3 - 4.6 kcal/mol) and formed three hydrogen bonds with Asp125, Arg201 and Lys202. Despite the inconclusive molecular docking result, chlorpyrifos was consistently shown to be the least favored substrate of the DehH2 in MD simulations and MM-PBSA calculations. Results of MD simulations revealed the DehH2-haloacid- (RMSD 0.15 - 0.25 nm) and DehH2-haloacetates (RMSF 0.05 - 0.25 nm) were more stable, with the DehH2-L-2CP complex being the most stable while the least was the DehH2-chlorpyrifos (RMSD 0.295 nm; RMSF 0.05 - 0.59 nm). The Molecular Mechanics Poisson-Boltzmann Surface Area calculations showed the DehH2-L-2CP complex (-24.27 kcal/mol) having the lowest binding energy followed by DehH2-MCA (-22.78 kcal/mol), DehH2-D-2CP (-21.82 kcal/mol), DehH2-3CP (-21.11 kcal/mol), DehH2-2,2-DCP (-18.34 kcal/mol), DehH2-2,3-DCP (-8.34 kcal/mol), DehH2-TCA (-7.62 kcal/mol), while chlorpyrifos was unable to spontaneously bind to DehH2 (+127.16 kcal/mol). In a nutshell, the findings of this study offer valuable insights into the rational tailoring of the DehH2 for expanding its substrate specificity and catalytic activity in the near future.Communicated by Ramaswamy H. Sarma.
    Matched MeSH terms: Environmental Pollutants
  17. Chitosan modifications for adsorption of pollutants - A review
    Saheed IO, Oh WD, Suah FBM
    J Hazard Mater, 2021 04 15;408:124889.
    PMID: 33418525 DOI: 10.1016/j.jhazmat.2020.124889
    In recent times, research interest into the development of biodegradable, cost-effective and environmental friendly adsorbents with favourable properties for adsorption of pollutants is a challenge. Modification of chitosan via different physical and chemical methods have gained attention as a promising approach for removing organic (such as dyes and pharmaceuticals) and inorganic (such as metal/metal ions) pollutants from aqueous medium. In this regard, researchers have reported grafting and cross-linking approach among others as a potentially useful method for chitosan's modification for improved adsorption efficiency with respect to pollutant uptake. This article reviews the trend in chitosan modification, with regards to the summary of some recently published works on modification of chitosan and their adsorption application in pollutants (metal ion, dyes and pharmaceuticals) removal from aqueous medium. The review uniquely highlights some common cross-linkers and grafting procedures for chitosan modification, their influence on structure and adsorption capacity of modified-chitosan with respect to pollutants removal. Findings revealed that the performance of modified chitosan for adsorption of pollutants depends largely on the modification method adopted, materials used for the modification and adsorption experimental conditions. Cross-linking is commonly utilized for improving the chemical and mechanical stabilities of chitosan but usually decreases adsorption capacity of chitosan/modified-chitosan for adsorption of pollutants. However, literature survey revealed that adsorption capacity of cross-linked chitosan based materials have been enhanced in recently published works either by grafting, incorporation of solid adsorbents (e.g metals, clays and activated carbon) or combination of both prior to cross-linking.
    Matched MeSH terms: Environmental Pollutants
  18. Real-time and visual sensing devices based on pH-control assembled lanthanide-barium nano-cluster
    Liu M, Li H, Bai L, Zheng K, Zhao Z, Chen Z, et al.
    J Hazard Mater, 2021 07 05;413:125291.
    PMID: 33588337 DOI: 10.1016/j.jhazmat.2021.125291
    Real-time and visual monitoring of pollutants in the air is of great importance since they are usually cannot be seen, smelled, or touched. Lanthanide nano-cluster is a kind of luminescent sensor for various species. However, controlling synthesis of lanthanide nano-cluster remains experimentally challenging. In this work, four series of lanthanide-barium (Ln-Ba) nano-clusters of Dy2Ba (1), Tb2Ba2 (2), Ln4Ba3 (Ln = Tb, 3a; Eu, 3b), Tb4Ba4 (4) were assembled through precisely controlling the pH of the reactant solutions. The work features the first example that the number of cluster's nuclei changes regularly with the pH. Moreover, investigation reveals that nano-cluster 3a is a highly selective and sensitive sensor towards acetylacetone (acac) and aniline. Interestingly, easy-to-use sensing devices of test paper, agarose gel, and five kinds of film on CaCO3, polyfoam, coin, mask, and wall that based on 3a were fabricated by facile methods. The seven sensing devices showed remarkable ability to sense aniline and acac vapors with visibility to the naked eyes. This is the first work on multiple real-time and visual sensing devices based on the lanthanide nano-cluster.
    Matched MeSH terms: Environmental Pollutants
  19. A comprehensive review on magnetic carbon nanotubes and carbon nanotube-based buckypaper for removal of heavy metals and dyes
    Khan FSA, Mubarak NM, Tan YH, Khalid M, Karri RR, Walvekar R, et al.
    J Hazard Mater, 2021 07 05;413:125375.
    PMID: 33930951 DOI: 10.1016/j.jhazmat.2021.125375
    Industrial effluents contain several organic and inorganic contaminants. Among others, dyes and heavy metals introduce a serious threat to drinking waterbodies. These pollutants can be noxious or carcinogenic in nature, and harmful to humans and different aquatic species. Therefore, it is of high importance to remove heavy metals and dyes to reduce their environmental toxicity. This has led to an extensive research for the development of novel materials and techniques for the removal of heavy metals and dyes. One route to the removal of these pollutants is the utilization of magnetic carbon nanotubes (CNT) as adsorbents. Magnetic carbon nanotubes hold remarkable properties such as surface-volume ratio, higher surface area, convenient separation methods, etc. The suitable characteristics of magnetic carbon nanotubes have led them to an extensive search for their utilization in water purification. Along with magnetic carbon nanotubes, the buckypaper (BP) membranes are also favorable due to their unique strength, high porosity, and adsorption capability. However, BP membranes are mostly used for salt removal from the aqueous phase and limited literature shows their applications for removal of heavy metals and dyes. This study focuses on the existence of heavy metal ions and dyes in the aquatic environment, and methods for their removal. Various fabrication approaches for the development of magnetic-CNTs and CNT-based BP membranes are also discussed. With the remarkable separation performance and ultra-high-water flux, magnetic-CNTs, and CNT-based BP membranes have a great potential to be the leading technologies for water treatment in future.
    Matched MeSH terms: Environmental Pollutants
  20. Fulltext Metagenomic datasets of air samples collected during episodes of severe smoke-haze in Malaysia
    James GL, Latif MT, Isa MNM, Bakar MFA, Yusuf NYM, Broughton W, et al.
    Data Brief, 2021 Jun;36:107124.
    PMID: 34095374 DOI: 10.1016/j.dib.2021.107124
    Transboundary emissions of smoke-haze from land and forest fires have recurred annually during the dry period (June to October, over the past few decades) in South East Asia. Hazardous air quality has been recorded in Malaysia during these episodes. Agricultural practices such as slash-and-burn of biomass and peat fires particularly in Sumatera and Kalimantan, Indonesia, have been implicated as the major causes of the haze. Past findings have shown that a diversity of microbes can thrive in air including in smoke-haze polluted air. In this study, metagenomic data were generated to reveal the diversity of microorganisms in air during days with and without haze. Air samples were collected during non-haze (2013A01) and two haze (2013A04 and 2013A05) periods in the month of June 2013. DNA was extracted from the samples, subjected to Multiple Displacement Amplification and whole genome sequencing (Next Generation Sequencing) using the HiSeq 2000 Platform. Extensive bio-informatic analyses of the raw sequence data then followed. Raw reads from these six air samples were deposited in the NCBI SRA databases under Bioproject PRJNA662021 with accession numbers SRX9087478, SRX9087479 and SRX9087480.
    Matched MeSH terms: Environmental Pollutants
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