Displaying publications 21 - 40 of 49 in total

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  1. Fulltext Exploration of Microbial Factories for Synthesis of Nanoparticles - A Sustainable Approach for Bioremediation of Environmental Contaminants
    Kapoor RT, Salvadori MR, Rafatullah M, Siddiqui MR, Khan MA, Alshareef SA
    Front Microbiol, 2021;12:658294.
    PMID: 34149647 DOI: 10.3389/fmicb.2021.658294
    The nanomaterials synthesis is an intensifying research field due to their wide applications. The high surface-to-volume ratio of nanoparticles and quick interaction capacity with different particles make them as an attractive tool in different areas. Conventional physical and chemical procedures for development of metal nanoparticles become outmoded due to extensive production method, energy expenditure and generation of toxic by-products which causes significant risks to the human health and environment. Hence, there is a growing requirement to search substitute, non-expensive, reliable, biocompatible and environmental friendly methods for development of nanoparticles. The nanoparticles synthesis by microorganisms has gained significant interest due to their potential to synthesize nanoparticles in various sizes, shape and composition with different physico-chemical properties. Microbes can be widely applied for nanoparticles production due to easy handling and processing, requirement of low-cost medium such as agro-wastes, simple scaling up, economic viability with the ability of adsorbing and reducing metal ions into nanoparticles through metabolic processes. Biogenic synthesis of nanoparticles offers clean, non-toxic, environmentally benign and sustainable approach in which renewable materials can be used for metal reduction and nanoparticle stabilization. Nanomaterials synthesized through microbes can be used as a pollution abatement tool as they also contain multiple functional groups that can easily target pollutants for efficient bioremediation and promotes environmental cleanup. The objective of the present review is to highlight the significance of micro-organisms like bacteria, actinomycetes, filamentous fungi, yeast, algae and viruses for nanoparticles synthesis and advantages of microbial approaches for elimination of heavy metals, dyes and wastewater treatment.
  2. Fulltext Development of Ultra-Performance Liquid Chromatography-Mass Spectrometry Method for Simultaneous Determination of Three Cationic Dyes in Environmental Samples
    Hakami AAH, Wabaidur SM, Ali Khan M, Abdullah Alothman Z, Rafatullah M, Siddiqui MR
    Molecules, 2020 Oct 06;25(19).
    PMID: 33036289 DOI: 10.3390/molecules25194564
    Lower dye concentrations and the presence of several dyes along with other matrices in environmental samples restrict their determination. Herein, a highly sensitive and rapid ultra-performance tandem mass spectrometric method was developed for simultaneous determination of cationic dyes, namely methylene blue (MB), rhodamine B (RB) and crystal violet (CV), in environmental samples. To preconcentrate environmental samples, solid-phase extraction cartridges were developed by using hydrogen peroxide modified pistachio shell biomass (MPSB). The surface morphological and chemical functionalities of MPSB were well characterized. The developed method was validated considering different validation parameters. In terms of accuracy and precision, the %RSD for all three dyes at all four concentration points was found to be between 1.26 and 2.76, while the accuracy reported in terms of the recovery was found to be 98.02%-101.70%. The recovery was found to be in the range of 98.11% to 99.55%. The real sample analysis shows that MB, RB, and CV were found in the ranges of 0.39-5.56, 0.32-1.92 and 0.27-4.36 μg/mL, respectively.
  3. Fulltext Optimization for Liquid-Liquid Extraction of Cd(II) over Cu(II) Ions from Aqueous Solutions Using Ionic Liquid Aliquat 336 with Tributyl Phosphate
    Lee LY, Morad N, Ismail N, Talebi A, Rafatullah M
    Int J Mol Sci, 2020 Sep 18;21(18).
    PMID: 32962106 DOI: 10.3390/ijms21186860
    This study investigates the separation of two heavy metals, Cd(II) and Cu(II), from the mixed synthetic feed using a liquid-liquid extraction. The current study uses tri-octyl methylammonium chloride (Aliquat 336) as the extractant (with tributyl phosphate (TBP) as a phase modifier), diluted in toluene, in order to investigate the selective extraction of Cd(II) over Cu(II) ions. We investigate the use of ethylenediaminetetraacetic acid (EDTA) as a masking agent for Cu(II), when added in aqueous feed, for the selective extraction of Cd(II). Five factors that influence the selective extraction of Cd(II) over Cu(II) (the equilibrium pH (pHeq), Aliquat 336 concentration (Aliquat 336), TBP concentration (TBP), EDTA concentration (EDTA), and organic to aqueous ratio (O:A)) were analyzed. Results from a 25-1 fractional factorial design show that Aliquat 336 significantly influenced Cd(II) extraction, whereas EDTA was statistically significant for the antagonistic effect on the E% of Cu(II) in the same system. Moreover, results from optimization experiment showed that the optimum conditions are Aliquat 336 concentration of 99.64 mM and EDTA concentration of 48.86 mM-where 95.89% of Cd(II) was extracted with the least extracted Cu(II) of 0.59%. A second-order model was fitted for optimization of Cd(II) extraction with a R2 value of 0.998, and ANOVA results revealed that the model adequately fitted the data at a 5% significance level. Interaction between Aliquat 336 and Cd(II) has been proven via FTIR qualitative analysis, whereas the addition of TBP does not affect the extraction mechanism.
  4. Fulltext Bioflocculants Produced by Bacterial Strains Isolated from Palm Oil Mill Effluent for Application in the Removal of Eriochrome Black T Dye from Water
    Abbas SZ, Yong YC, Ali Khan M, Siddiqui MR, Hakami AAH, Alshareef SA, et al.
    Polymers (Basel), 2020 Jul 13;12(7).
    PMID: 32668712 DOI: 10.3390/polym12071545
    Four strains of bioflocculant-producing bacteria were isolated from a palm oil mill effluent (POME). The four bacterial strains were identified as Pseudomonas alcaliphila (B1), Pseudomonas oleovorans (B2), Pseudomonas chengduensis (B3), and Bacillus nitratireducens (B4) by molecular identification. Among the four bacterial strains, Bacillus nitratireducens (B4) achieved the highest flocculating activity (49.15%) towards kaolin clay suspension after eight hours of cultivation time and was selected for further studies. The optimum conditions for Eriochrome Black T (EBT) flocculation regarding initial pH, type of cation, and B4 dosage were determined to be pH 2, Ca2⁺ cations, and a dosage of 250 mL/L of nutrient broth containing B4. Under these conditions, above 90% of EBT dye removal was attained. Fourier transform infrared spectroscopic (FT-IR) analysis of the bioflocculant revealed the presence of hydroxyl, alkyl, carboxyl, and amino groups. This bioflocculant was demonstrated to possess a good flocculating activity, being a promissory, low-cost, harmless, and environmentally friendly alternative for the treatment of effluents contaminated with dyes.
  5. Fulltext Bio-Mediated Synthesis of Reduced Graphene Oxide Nanoparticles from Chenopodium album: Their Antimicrobial and Anticancer Activities
    Umar MF, Ahmad F, Saeed H, Usmani SA, Owais M, Rafatullah M
    Nanomaterials (Basel), 2020 Jun 01;10(6).
    PMID: 32492878 DOI: 10.3390/nano10061096
    A novel method of preparing reduced graphene oxide (RGOX) from graphene oxide (GOX) was developed employing vegetable extract, Chenopodium album, as a reducing and stabilizing agent. Chenopodium album is a green leafy vegetable with a low shelf life, fresh leaves of this vegetable are encouraged to be used due to high water content. The previously modified 'Hummers method' has been in practice for the preparation of GOX by using precursor graphite powder. In this study, green synthesis of RGOX was functionally verified by employing FTIR and UV-visible spectroscopy, along with SEM and TEM. Our results demonstrated typical morphology of RGOX stacked in layers that appeared as silky, transparent, and rippled. The antibacterial activity was shown by analyzing minimal inhibitory concentration values, agar diffusion assay, fluorescence techniques. It showed enhanced antibacterial activity against Gram-positive and Gram-negative bacteria in comparison to GOX. It has also been shown that the synthesized compound exhibited enhanced antibiofilm activity as compared to its parent compound. The efficacy of RGOX and GOX has been demonstrated on a human breast cancer cell line, which suggested RGOX as a potential anticancer agent.
  6. Fulltext Recent Advances in Anodes for Microbial Fuel Cells: An Overview
    Yaqoob AA, Ibrahim MNM, Rafatullah M, Chua YS, Ahmad A, Umar K
    Materials (Basel), 2020 May 01;13(9).
    PMID: 32369902 DOI: 10.3390/ma13092078
    The recycling and treatment of wastewater using microbial fuel cells (MFCs) has been attracting significant attention as a way to control energy crises and water pollution simultaneously. Despite all efforts, MFCs are unable to produce high energy or efficiently treat pollutants due to several issues, one being the anode's material. The anode is one of the most important parts of an MFC. Recently, different types of anode materials have been developed to improve the removal rate of pollutants and the efficiency of energy production. In MFCs, carbon-based materials have been employed as the most commonly preferred anode material. An extensive range of potentials are presently available for use in the fabrication of anode materials and can considerably minimize the current challenges, such as the need for high quality materials and their costs. The fabrication of an anode using biomass waste is an ideal approach to address the present issues and increase the working efficiency of MFCs. Furthermore, the current challenges and future perspectives of anode materials are briefly discussed.
  7. Selective adsorption and recovery of volatile fatty acids from fermented landfill leachate by activated carbon process
    Talebi A, Razali YS, Ismail N, Rafatullah M, Azan Tajarudin H
    Sci Total Environ, 2020 Mar 10;707:134533.
    PMID: 31865088 DOI: 10.1016/j.scitotenv.2019.134533
    An adsorption-desorption process was applied on fermented landfill leachate to adsorb and recover acetic and butyric acid, using activated carbon. In this study, the first, volatile fatty acids adsorption process from fermented leachate was optimized, by investigating various affecting factors such as pH, time, agitation speed, activated carbon dosage, and temperature. The optimum condition for maximum adsorption of 88.94% acetic acid and 98.53% butyric acid, was 19.79 %wt activated carbon dosage, 40.00 rpm of agitation speed, in 9.45 °C and contact time of 179.89 h, while the pH of the substrate was kept fixed at pH:3.0. Results of X-ray fluorescence (XRF) spectrometry, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and zeta potential revealed that carbon is the dominant component in the adsorbent with a significant effect to remove organic impurities, and it was observed that the activated carbon after the adsorption process showed an amorphous structure peak with a large internal surface area and pore volume. The results exposed that the adsorption on the surface of activated carbon was due to the chemisorption, and the chemisorption mechanism was supported by covalent bonding. The kinetic study displayed excellent fit to Pseudo-second order kinetics model. The second phase of this study was to recover the adsorbed VFAs using multistage desorption unit, in which application of deionized water and ethanol (as desorption agents) resulted in 89.1% of acetic acid and 67.8% of the butyric acid recovery.
  8. Fulltext Enrichment of Eucalyptus oil nanoemulsion by micellar nanotechnology: transdermal analgesic activity using hot plate test in rats' assay
    Aziz ZAA, Nasir HM, Ahmad A, Setapar SHM, Ahmad H, Noor MHM, et al.
    Sci Rep, 2019 Sep 23;9(1):13678.
    PMID: 31548590 DOI: 10.1038/s41598-019-50134-y
    Eucalyptus globulus is an aromatic medicinal plant which known for its 1,8-cineole main pharmacological constituent exhibits as natural analgesic agent. Eucalyptus globulus-loaded micellar nanoparticle was developed via spontaneous emulsification technique and further evaluation for its analgesic efficacy study, in vivo analgesic activity assay in rats. The nanoemulsion system containing Eucalyptus-micelles was optimized at different surfactant types (Tween 40, 60 and 80) and concentrations (3.0, 6.0, 9.0, 12.0, 15.0, and 18.0 wt. %). These formulations were characterized by thermodynamically stability, viscosity, micelles particle size, pH, and morphology structure. The spontaneous emulsification technique offered a greener micelles formation in nanoemulsion system by slowly titrated of organic phase, containing Eucalyptus globulus (active compound), grape seed oil (carrier oil) and hydrophilic surfactant into aqueous phase, and continuously stirred for 30 min to form a homogeneity solution. The characterizations evaluation revealed an optimized formulation with Tween 40 surfactant type at 9.0 wt. % of surfactant concentration promoted the most thermodynamic stability, smaller micelles particle size (d = 17.13 ± 0.035 nm) formed with spherical shape morphological structure, and suitable in viscosity (≈2.3 cP) and pH value (6.57) for transdermal purpose. The in vivo analgesic activity assay of optimized emulsion showed that the transdermal administration of micellar nanoparticle of Eucalyptus globulus on fore and hind limb of rats, possessed the central and peripheral analgesic effects by prolonged the rats pain responses towards the heat stimulus after being put on top of hot plate (55 °C), with longest time responses, 40.75 s at 60 min after treatment administration. Thus, this study demonstrated that micellar nanoparticle of Eucalyptus globulus formed in nanoemulsion system could be promising as an efficient transdermal nanocarrier for the analgesic therapy alternative.
  9. Heteroatom-doped magnetic hydrochar to remove post-transition and transition metals from water: Synthesis, characterization, and adsorption studies
    Khan MA, Alqadami AA, Otero M, Siddiqui MR, Alothman ZA, Alsohaimi I, et al.
    Chemosphere, 2019 Mar;218:1089-1099.
    PMID: 30609488 DOI: 10.1016/j.chemosphere.2018.11.210
    Efforts to improve water quality have led to the development of green and sustainable water treatment approaches. Herein, nitrogen-doped magnetized hydrochar (mSBHC-N) was synthesized, characterized, and used for the removal of post-transition and transition heavy metals, viz. Pb2+ and Cd2+ from aqueous environment. mSBHC-N was found to be mesoporous (BET surface area - 62.5 m2/g) and paramagnetic (saturation magnetization - 44 emu/g). Both, FT-IR (with peaks at 577, 1065, 1609 and 3440 cm-1 corresponding to Fe - O stretching vibrations, C - N stretching, N - H in-plane deformation and stretching) and XPS analyses (with peaks at 284.4, 400, 530, 710 eV due to C 1s, N 1s, O 1s, and Fe 2p) confirmed the presence of oxygen and nitrogen containing functional groups on mSBHC-N. The adsorption of Pb2+ and Cd2+ was governed by oxygen and nitrogen functionalities through electrostatic and co-ordination forces. 75-80% of Pb2+ and Cd2+ adsorption at Co: 25 mg/L, either from deionized water or humic acid solution was accomplished within 15 min. The data was fitted to pseudo-second-order kinetic and Langmuir isotherm models, with maximum monolayer adsorption capacities being 323 and 357 mg/g for Cd2+and Pb2+ at 318 K, respectively. Maximum Cd2+ (82.6%) and Pb2+ (78.7%) were eluted with 0.01 M HCl, simultaneously allowing minimum iron leaching (2.73%) from mSBHC-N. In conclusion, the study may provide a novel, economical, and clean route to utilize agro-waste, such as sugarcane bagasse (SB), for aquatic environment remediation.
  10. Fulltext Adsorption of Rhodamine B dye from aqueous solution onto acid treated banana peel: Response surface methodology, kinetics and isotherm studies
    Oyekanmi AA, Ahmad A, Hossain K, Rafatullah M
    PLoS One, 2019;14(5):e0216878.
    PMID: 31091269 DOI: 10.1371/journal.pone.0216878
    The adsorption of rhodamine B (RhB) using acid modified banana peels has been examined. Chemical characteristics of the adsorbents were observed in order to determine active functional groups. The major functional groups on the surface were OH, C = O, C = C and C-O-C. Interactions between operational parameters were studied using the central composite design (CCD) of response surface methodology (RSM). The predictions of the model output indicated that operational factors influenced responses at a confidence level of 95% (P<0.05). The optimum conditions for adsorption were pH 2 at a 0.2 g/L dose within 60 minutes of contact time. Isotherm studies were carried out using the optimized process variables. The data revealed that RhB adsorption fitted the Langmuir isotherm equation while the reduction of COD followed the Freundlich isotherm. Kinetic experiments fitted the pseudo second order model for RhB removal and COD reduction. The adsorption mechanism was not the only rate controlling step. Diffusion through the boundary layer described the pattern of adsorption.
  11. Essential Oils: Extraction Techniques, Pharmaceutical And Therapeutic Potential - A Review
    Aziz ZAA, Ahmad A, Setapar SHM, Karakucuk A, Azim MM, Lokhat D, et al.
    Curr Drug Metab, 2018;19(13):1100-1110.
    PMID: 30039757 DOI: 10.2174/1389200219666180723144850
    BACKGROUND: Essential oils are liquid extracts from aromatic plants, which have numerous applications in multiple industries. There are a variety of methods used for the extraction of essential oils, with each method exhibiting certain advantages and determining the biological and physicochemical properties of the extracted oils. Essential oils from different plant species contain more than 200 constituents which are comprised of volatile and non-volatile components. The application of essential oils as antimicrobial, anticancer, anti-inflammatory and anti-viral agents is due to their effective and efficient properties, inter alia.

    METHOD: Several advanced (supercritical fluid extraction, subcritical extraction liquid, solvent-free microwave extraction) and conventional (hydrodistillation, steam distillation, hydrodiffusion, solvent extraction) methods have been discussed for the extraction of essential oils. Advanced methods are considered as the most promising extraction techniques due to less extraction time, low energy consumption, low solvent used and less carbon dioxide emission.

    CONCLUSION: This manuscript reviewed the major research studies in the field and discussed several research findings on the chemical composition of essential oils, methods of oil extraction, and application of these oils in pharmaceutical and therapeutic fields. These essential oils can be used as anticancer, antimicrobial, antiviral, and as skin permeation enhancer agents.

  12. Fulltext Bioremediation and Electricity Generation by Using Open and Closed Sediment Microbial Fuel Cells
    Abbas SZ, Rafatullah M, Khan MA, Siddiqui MR
    Front Microbiol, 2018;9:3348.
    PMID: 30692985 DOI: 10.3389/fmicb.2018.03348
    The industrial contamination of marine sediments with mercury, silver, and zinc in Penang, Malaysia was studied with bio-remediation coupled with power generation using membrane less open (aerated) and closed (non-aerated) sediment microbial fuel cells (SMFCs). The prototype for this SMFC is very similar to a natural aquatic environment because it is not stimulated externally and an oxygen sparger is inserted in the cathode chamber to create the aerobic environment in the open SMFC and no oxygen supplied in the closed SMFC. The open and closed SMFCs were showed the maximum voltage generation 300.5 mV (77.75 mW/m2) and 202.7 mV (45.04 (mW/m2), respectively. The cyclic voltammetry showed the oxidation peak in open SMFCs at +1.9 μA and reduction peak at -0.3 μA but in closed SMFCs oxidation and reduction peaks were noted at +1.5 μA and -1.0 μA, respectively. The overall impedance (anode, cathode and solution) of closed SMFCs was higher than open SMFCs. The charge transfer impedance showed that the rates of substrate oxidation and reduction were very low in the closed SMFCs than open SMFCs. The Nyquist arc indicated that O2 act as electron acceptor in the open SMFCs and CO2 in the closed SMFCs. The highest remediation efficiency of toxic metals [Hg (II) ions, Zn (II) ions, and Ag (I) ions] in the open SMFCs were 95.03%, 86.69%, and 83.65% in closed SMFCs were 69.53%, 66.57%, and 65.33%, respectively, observed during 60-80 days. The scanning electron microscope and 16S rRNA analysis showed diverse exoelectrogenic community in the open SMFCs and closed SMFCs. The results demonstrated that open SMFCs could be employed for the power generation and bioremediation of pollutants.
  13. A review on chitosan-cellulose blends and nanocellulose reinforced chitosan biocomposites: Properties and their applications
    H P S AK, Saurabh CK, A S A, Nurul Fazita MR, Syakir MI, Davoudpour Y, et al.
    Carbohydr Polym, 2016 Oct 05;150:216-26.
    PMID: 27312632 DOI: 10.1016/j.carbpol.2016.05.028
    Chitin is one of the most abundant natural polymers in world and it is used for the production of chitosan by deacetylation. Chitosan is antibacterial in nature, non-toxic, and biodegradable thus it can be used for the production of biodegradable film which is a green alternative to commercially available synthetic counterparts. However, their poor mechanical and thermal properties restricted its wide spread applications. Chitosan is highly compatible with other biopolymers thus its blending with cellulose and/or incorporation of nanofiber isolated from cellulose namely cellulose nanofiber and cellulose nanowhiskers are generally useful. Cellulosic fibers in nano scale are attractive reinforcement in chitosan to produce environmental friendly composite films with improved physical properties. Thus chitosan based composites have wide applicability and potential in the field of biomedical, packaging and water treatment. This review summarises properties and preparation procedure of chitosan-cellulose blends and nano size cellulose reinforcement in chitosan bionanocomposites for different applications.
  14. Bioremediation and Detoxification of the Textile Wastewater with Membrane Bioreactor Using the White-rot Fungus and Reuse of Wastewater
    Hossain K, Quaik S, Ismail N, Rafatullah M, Avasan M, Shaik R
    Iran J Biotechnol, 2016 Sep;14(3):154-162.
    PMID: 28959331 DOI: 10.15171/ijb.1216
    BACKGROUND: Application of membrane technology to wastewater treatment has expanded over the last decades due to increasingly stringent legislation, greater opportunities for water reuse/recycling processes and continuing advancement in membrane technology.

    OBJECTIVES: In the present study, a bench-scale submerged microfiltration membrane bioreactor (MBR) was used to assess the treatment of textile wastewater.

    MATERIALS AND METHODS: The decolorization capacity of white-rot fungus coriolus versicolor was confirmed through agar plate and liquid batch studies. The temperature and pH of the reactor were controlled at 29±1°C and 4.5±2, respectively. The bioreactor was operated with an average flux of 0.05 m.d(-1) (HRT=15hrs) for a month.

    RESULTS: Extensive growth of fungi and their attachment to the membrane led to its fouling and associated increase of the transmembrane pressure requiring a periodic withdrawal of sludge and membrane cleaning. However, stable decoloration activity (approx. 98%), BOD (40-50%), COD (50-67%) and total organic carbon (TOC) removal (>95%) was achieved using the entire system (fungi + membrane), while the contribution of the fungi culture alone for TOC removal, as indicated by the quality of the reactor supernatant, was 35-50% and 70%, respectively.

    CONCLUSIONS: The treated wastewater quality satisfied the requirement of water quality for dyeing and finishing process excluding light coloration. Therefore, textile wastewater reclamation and reuse is a promising alternative, which can both conserve or supplement the available water resource and reduce or eliminate the environmental pollution.

  15. Catalytic thermolysis in treating Cibacron Blue in aqueous solution: Kinetics and degradation pathway
    Su CX, Teng TT, Wong YS, Morad N, Rafatullah M
    Chemosphere, 2016 Mar;146:503-10.
    PMID: 26741557 DOI: 10.1016/j.chemosphere.2015.12.048
    A thermal degradation pathway of the decolourisation of Reactive Cibacron Blue F3GA (RCB) in aqueous solution through catalytic thermolysis is established. Catalytic thermolysis is suitable for the removal of dyes from wastewater as it breaks down the complex dye molecules instead of only transferring them into another phase. RCB is a reactive dye that consists of three main groups, namely anthraquinone, benzene and triazine groups. Through catalytic thermolysis, the bonds that hold the three groups together were effectively broken and at the same time, the complex molecules degraded to form simple molecules of lower molecular weight. The degradation pathway and products were characterized and determined through UV-Vis, FT-IR and GCMS analysis. RCB dye molecule was successfully broken down into simpler molecules, namely, benzene derivatives, amines and triazine. The addition of copper sulphate, CuSO4, as a catalyst, hastens the thermal degradation of RCB by aiding in the breakdown of large, complex molecules. At pH 2 and catalyst mass loading of 5 g/L, an optimum colour removal of 66.14% was observed. The degradation rate of RCB is well explained by first order kinetics model.
  16. Chitosan hydrogel beads impregnated with hexadecylamine for improved reactive blue 4 adsorption
    Vakili M, Rafatullah M, Ibrahim MH, Abdullah AZ, Salamatinia B, Gholami Z
    Carbohydr Polym, 2016 Feb 10;137:139-146.
    PMID: 26686114 DOI: 10.1016/j.carbpol.2015.09.017
    Adsorption performance of chitosan (CS) hydrogel beads was investigated after impregnation of CS with hexadecylamine (HDA) as a cationic surfactant, for the elimination of reactive blue 4 (RB4) from wastewater. The CS/HDA beads formed with 3.8% HDA were the most effective adsorbent. The adsorption capacity was increased by 1.43 times from 317 mg/g (CS) to 454 mg/g (CS/HDA). The RB4 removal increased with decrease in the pH of dye solution from 4 to 9. The isotherm data obtained from RB4 adsorption on CS and CS/HDA are adequately described by Freundlich model (R(2)=0.946 and 0.934, χ(2)=22.414 and 64.761). The kinetic study revealed that the pseudo-second-order rate model (R(2)=0.996 and 0.997) was in better agreement with the experimental data. The negative values of ΔG° (-2.28 and -6.30 kJ/mol) and ΔH° (-172.18 and -101.62 kJ/mol) for CS beads and HDA modified CS beads, respectively; suggested a spontaneous and exothermic process for RB4 adsorption.
  17. Elimination of reactive blue 4 from aqueous solutions using 3-aminopropyl triethoxysilane modified chitosan beads
    Vakili M, Rafatullah M, Salamatinia B, Ibrahim MH, Abdullah AZ
    Carbohydr Polym, 2015 Nov 05;132:89-96.
    PMID: 26256328 DOI: 10.1016/j.carbpol.2015.05.080
    The adsorption behavior of chitosan (CS) beads modified with 3-aminopropyl triethoxysilane (APTES) for the removal of reactive blue 4 (RB4) in batch studies has been investigated. The effects of modification conditions, such as the APTES concentration, temperature and reaction time on RB4 removal, were studied. The adsorbent prepared at a concentration of 2 wt% APTES for 8h at 50 °C was the most effective one for RB4 adsorption. The adsorption capacity of modified CS beads (433.77 mg/g) was 1.37 times higher than that of unmodified CS beads (317.23 mg/g). The isotherm data are adequately described by a Freundlich model, and the kinetic study revealed that the pseudo-second-order rate model was in better agreement with the experimental data. The negative values of the thermodynamic parameters, including ΔG° (-2.28 and -4.70 kJ/mol at 30 ± 2 °C), ΔH° (-172.18 and -43.82 kJ/mol) and ΔS° (-560.71 and -129.08 J/mol K) for CS beads and APTES modified beads, respectively, suggest that RB4 adsorption is a spontaneous and exothermic process.
  18. Titanium-based nanocomposite materials: a review of recent advances and perspectives
    Shahadat M, Teng TT, Rafatullah M, Arshad M
    Colloids Surf B Biointerfaces, 2015 Feb 1;126:121-37.
    PMID: 25543989 DOI: 10.1016/j.colsurfb.2014.11.049
    This article explains recent advances in the synthesis and characterization of novel titanium-based nanocomposite materials. Currently, it is a pressing concern to develop innovative skills for the fabrication of hybrid nanomaterials under varying experimental conditions. This review generally focuses on the adsorption behavior of nanocomposites for the exclusion of organic and inorganic pollutants from industrial effluents and their significant applications in various fields. The assessment of recently published articles on the conjugation of organic polymers with titanium has revealed that these materials may be a new means of managing aquatic pollution. These nanocomposite materials not only create alternative methods for designing novel materials, but also develop innovative industrial applications. In the future, titanium-based hybrid nanomaterials are expected to open new approaches for demonstrating their outstanding applications in diverse fields.
  19. Isolation, identification, characterization, and evaluation of cadmium removal capacity of Enterobacter species
    Abbas SZ, Rafatullah M, Ismail N, Lalung J
    J Basic Microbiol, 2014 Dec;54(12):1279-87.
    PMID: 24852724 DOI: 10.1002/jobm.201400157
    This study focused on the isolation and characterization of high cadmium-resistant bacterial strains, possible exploitation of its cadmium-accumulation and cadmium-induced proteins. Cadmium-resistant bacterial strains designated as RZ1 and RZ2 were isolated from industrial wastewater of Penang, Malaysia. These isolates were identified as Enterobacter mori and Enterobacter sp. WS12 on the basis of phenotypic, biochemical and 16S rDNA sequence based molecular phylogenetic characteristics. Both isolates were Gram negative, cocci, and growing well in Lauria-Bertani broth medium at 35 °C temperature and pH 7.0. Results also indicated that Enterobacter mori and Enterobacter sp. WS12are capable to remove 87.75 and 85.11% of the cadmium from 100 µg ml(-1) concentration, respectively. This study indicates that these strains can be useful as an inexpensive and efficient bioremediation technology to remove and recover the cadmium from wastewater.
  20. Application of chitosan and its derivatives as adsorbents for dye removal from water and wastewater: a review
    Vakili M, Rafatullah M, Salamatinia B, Abdullah AZ, Ibrahim MH, Tan KB, et al.
    Carbohydr Polym, 2014 Nov 26;113:115-30.
    PMID: 25256466 DOI: 10.1016/j.carbpol.2014.07.007
    Chitosan based adsorbents have received a lot of attention for adsorption of dyes. Various modifications of this polysaccharide have been investigated to improve the adsorption properties as well as mechanical and physical characteristics of chitosan. This review paper discusses major research topics related to chitosan and its derivatives for application in the removal of dyes from water. Modification of chitosan changes the original properties of this material so that it can be more suitable for adsorption of different types of dye. Many chitosan derivatives have been obtained through chemical and physical modifications of raw chitosan that include cross-linking, grafting and impregnation of the chitosan backbone. Better understanding of these varieties and their affinity toward different types of dye can help future research to be properly oriented to address knowledge gaps in this area. This review provides better opportunity for researchers to better explore the potential of chitosan-derived adsorbents for removal of a great variety of dyes.
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