Displaying publications 61 - 80 of 296 in total

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  1. Performance of combined sodium persulfate/H2O2 based advanced oxidation process in stabilized landfill leachate treatment
    Hilles AH, Abu Amr SS, Hussein RA, El-Sebaie OD, Arafa AI
    J Environ Manage, 2016 Jan 15;166:493-8.
    PMID: 26580899 DOI: 10.1016/j.jenvman.2015.10.051
    A combination of persulfate and hydrogen peroxide (S2O8(2-)/H2O2) was used to oxidizelandfill leachate. The reaction was performed under varying S2O8(2-)/H2O2 ratio (g/g), S2O8(2-)/H2O2 dosages (g/g), pH, and reaction time (minutes), so as to determine the optimum operational conditions. Results indicated that under optimum operational conditions (i.e. 120 min of oxidation using a S2O8(2-)/H2O2 ratio of 1 g/1.47 g at a persulfate and hydrogen peroxide dosage of 5.88 g/50 ml and8.63 g/50 ml respectively, at pH 11) removal of 81% COD and 83% NH3-N was achieved. In addition, the biodegradability (BOD5/COD ratio) of the leachate was improved from 0.09 to 0.17. The results obtained from the combined use of (S2O8(2-)/H2O2) were compared with those obtained with sodium persulfate only, hydrogen peroxide only and sodium persulfate followed by hydrogen peroxide. The combined method (S2O8(2-)/H2O2) achieved higher removal efficiencies for COD and NH3-N compared with the other methods using a single oxidizing agent. Additionally, the study has proved that the combination of S2O8(2-)/H2O2 is more efficient than the sequential use of sodium persulfate followed by hydrogen peroxide in advanced oxidation processes aiming at treatingstabilizedlandfill leachate.
    Matched MeSH terms: Hydrogen Peroxide
  2. Irrigating the pulp space
    Walker D
    Endod Prac, 1999 Feb;2(1):8-12.
    PMID: 10740482
    Matched MeSH terms: Hydrogen Peroxide
  3. Fulltext Silver (I) Dicyanonitrosomethanide, Ag[ONC(CN)2] Complex as Catalyst for the Selective Oxidation of Styrene to Benzaldehyde
    Mohammad Anwar Mohamed Iqbal, Muhammad Zulhelmi Nazri, Mohammad Norazmi Ahmad, Erna Normaya Abdullah, Umie Fatihah Mohamad Haziz, Mohd Rizal Razali, et al.
    Science Letters, 2020;14(2):71-84.
    MyJurnal
    Silver (I) dicyanonitrosomethanide, Ag[ONC(CN)2] represent a 3D interwoven coordination polymer organization in which all the donor atoms of the functional groups of ONC(CN)2- are coordinated to the Ag(I). Oxidation of styrene utilizing H2O2 as an oxidant in acetonitrile (CH3CN) was used as a model reaction to investigate the catalytic potential of the Ag (I) complex. The CH3CN was chosen as the solvent based on the data collected from Conductor like Screening Model for Real Solvents (COSMO-RS) study. The data indicate that the Ag [ONC(CN)2] complex was compatible and soluble in CH3CN. Different parameters such as styrene:H2O2 molar ratio, reaction time, catalyst mass, and reaction temperature were studied. Highest styrene conversion (36%) with 100% selectivity towards benzaldehyde (BZ) was achieved when 25 mg catalyst, 1:1 styrene to H2O2 molar ratio were used. The reaction was carried out at 303 K for 3 h. The catalytic conversion of styrene to BZ is proposed to take place via [Ag-H2O2] adduct with styrene oxide (StO) as an intermediate. Molecular Electrostatic Potential (MEP) shows that the Ag atom has the highest probability to coordinate with the oxygen atom of H2O2. The MEP data confirms the proposed mechanism.
    Matched MeSH terms: Hydrogen Peroxide
  4. Fulltext Predicting the degradation potential of Acid blue 113 by different oxidants using quantum chemical analysis
    Asghar A, Bello MM, Raman AAA, Daud WMAW, Ramalingam A, Zain SBM
    Heliyon, 2019 Sep;5(9):e02396.
    PMID: 31517121 DOI: 10.1016/j.heliyon.2019.e02396
    In this work, quantum chemical analysis was used to predict the degradation potential of a recalcitrant dye, Acid blue 113, by hydrogen peroxide, ozone, hydroxyl radical and sulfate radical. Geometry optimization and frequency calculations were performed at 'Hartree Fock', 'Becke, 3-parameter, Lee-Yang-Parr' and 'Modified Perdew-Wang exchange combined with PW91 correlation' levels of study using 6-31G* and 6-31G** basis sets. The Fourier Transform-Raman spectra of Acid blue 113 were recorded and a complete analysis on vibrational assignment and fundamental modes of model compound was performed. Natural bond orbital analysis revealed that Acid blue 113 has a highly stable structure due to strong intermolecular and intra-molecular interactions. Mulliken charge distribution and molecular electrostatic potential map of the dye also showed a strong influence of functional groups on the neighboring atoms. Subsequently, the reactivity of the dye towards the oxidants was compared based on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy values. The results showed that Acid blue 113 with a HOMO value -5.227 eV exhibits a nucleophilic characteristic, with a high propensity to be degraded by ozone and hydroxyl radical due to their lower HOMO-LUMO energy gaps of 4.99 and 4.22 eV respectively. On the other hand, sulfate radical and hydrogen peroxide exhibit higher HOMO-LUMO energy gaps of 7.92 eV and 8.10 eV respectively, indicating their lower reactivity towards Acid blue 113. We conclude that oxidation processes based on hydroxyl radical and ozone would offer a more viable option for the degradation of Acid blue 113. This study shows that quantum chemical analysis can assist in selecting appropriate advanced oxidation processes for the treatment of textile effluent.
    Matched MeSH terms: Hydrogen Peroxide
  5. Fulltext Utilization of acid pre-treated coconut dregs as a substrate for production of detergent compatible lipase by Bacillus stratosphericus
    Mohd Zin NB, Mohamad Yusof B, Oslan SN, Wasoh H, Tan JS, Ariff AB, et al.
    AMB Express, 2017 Dec;7(1):131.
    PMID: 28651380 DOI: 10.1186/s13568-017-0433-y
    In recent years, many efforts have been directed to explore the methods to reduce the production costs of industrial lipase by improving the yield and the use of low-cost agricultural wastes. Coconut dregs, which is a lignocellulosic by-product from coconut oil and milk processing plants, is rich in cellulose (36%) and crude fat (9%). A newly isolated Bacillus stratosphericus has been demonstrated to perform cellulose hydrolysis on coconut dregs producing fermentable sugars. The highest extracellular lipase activity of 140 U/mL has been achieved in submerged fermentation with acid pre-treated coconut dregs. The lipase was found to be active over a wide range of temperatures and pHs. The activity of lipase can be generally increased by the presence of detergent ingredients such as Tween-80, cetyltrimethylammonium bromide, hydrogen peroxide and phosphate per sulphate. The great compatibility of lipase in commercial detergents has also underlined its potential as an additive ingredient in biodetergent formulations.
    Matched MeSH terms: Hydrogen Peroxide
  6. Enhancement of photocatalytic degradation of Malachite Green using iron doped titanium dioxide loaded on oil palm empty fruit bunch-derived activated carbon
    Loo WW, Pang YL, Lim S, Wong KH, Lai CW, Abdullah AZ
    Chemosphere, 2021 Jun;272:129588.
    PMID: 33482519 DOI: 10.1016/j.chemosphere.2021.129588
    Iron-doped titanium dioxide loaded on activated carbon (Fe-TiO2/AC) was successfully synthesized from oil palm empty fruit bunch (OPEFB) using sol-gel method. The properties of the synthesized pure TiO2, Fe-doped TiO2, AC, TiO2/AC and Fe-TiO2/AC were examined by various techniques such as field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and nitrogen adsorption-desorption analyses at 77 K. FE-SEM revealed that Fe-doped TiO2 particles were dispersed homogeneously on the AC surface. FT-IR demonstrated high surface hydroxylation after Fe doping on TiO2 and UV-Vis DRS showed that Fe-TiO2/AC had the lowest band gap energy. Catalytic performance results proved that Fe dopants could restrict the recombination rate of hole and electron pairs, whereas AC support improved the Malachite Green (MG) adsorption sites and active sites of the hybrid catalyst. Photocatalytic degradation of 100 mg/L MG in the presence of 1.0 g/L 15 wt% Fe-TiO2 incorporated with 25 wt% AC, initial solution pH of 4 and 3 mM H2O2 could achieve the highest removal efficiency of 97% after 45 min light irradiation. This work demonstrates a promising approach to synthesis an inexpensive and efficient Fe-TiO2/AC for the photocatalytic degradation of organic dye.
    Matched MeSH terms: Hydrogen Peroxide
  7. Calcium lignosulfonate improves proliferation of recalcitrant indica rice callus via modulation of auxin biosynthesis and enhancement of nutrient absorption
    Wan Abdullah WMAN, Tan NP, Low LY, Loh JY, Wee CY, Md Taib AZ, et al.
    Plant Physiol Biochem, 2021 Apr;161:131-142.
    PMID: 33581621 DOI: 10.1016/j.plaphy.2021.01.046
    Lignosulfonate (LS) is a commonly used to promote plant growth. However, the underlying growth promoting responses of LS in plant remain unknown. Therefore, this study was undertaken to elucidate the underlying growth promoting mechanisms of LS, specifically calcium lignosulfonate (CaLS). Addition of 100 mg/L CaLS in phytohormone-free media enhanced recalcitrant indica rice cv. MR219 callus proliferation rate and adventitious root formation. Both, auxin related genes (OsNIT1, OsTAA1 and OsYUC1) and tryptophan biosynthesis proteins were upregulated in CaLS-treated calli which corroborated with increased of endogenous auxin content. Moreover, increment of OsWOX11 gene on CaLS-treated calli implying that the raised of endogenous auxin was utilized as a cue to enhance adventitious root development. Besides, CaLS-treated calli showed higher nutrient ions content with major increment in calcium and potassium ions. Consistently, increased of potassium protein kinases genes (OsAKT1, OsHAK5, OsCBL, OsCIPK23 and OsCamk1) were also recorded. In CaLS treated calli, the significant increase of calcium ion was observed starting from week one while potassium ion only recorded significant increase on week two onwards, suggesting that increment of potassium ion might be dependent on the calcium ion content in the plant cell. Additionally, reduced callus blackening was also coherent with downregulation of ROS scavenging protein and reduced H2O2 content in CaLS-treated calli suggesting the role of CaLS in mediating cellular homeostasis via prevention of oxidative burst in the cell. Taken together, CaLS successfully improved MR219 callus proliferation and root formation by increasing endogenous auxin synthesis, enhancing nutrients uptake and regulating cellular homeostasis.
    Matched MeSH terms: Hydrogen Peroxide
  8. Formation of grassy TiO2 nanotube thin film by anodisation in peroxide electrolyte for Cr(VI) removal under ultraviolet radiation
    Taib MAA, Alias N, Jaafar M, Razak KA, Tan WK, Shahbudin IP, et al.
    Nanotechnology, 2020 Oct 23;31(43):435605.
    PMID: 32640434 DOI: 10.1088/1361-6528/aba3d8
    Arrays of TiO2 nanotubes (TiO2 NTs) with grassy surfaces were observed on titanium foil anodised at 60 V in fluorinated ethylene glycol (EG) with added hydrogen peroxide (H2O2). The grassy surface was generated by the chemical etching and dissolution of the surface of the TiO2 NTs walls, which was accelerated by the temperature increase on the addition of H2O2 . Upon annealing at 600 °C, the grassy part of the TiO2 NTs was found to consist of mostly anatase TiO2 whereas the bottom part of the anodic oxide comprised a mixture of anatase and rutile TiO2. The TiO2 NTs were then used to reduce hexavalent chromium (Cr(VI)) under ultraviolet radiation. They exhibited a rather efficient photocatalytic effect, with 100% removal of Cr(VI) after 30 min of irradiation. The fast removal of Cr(VI) was due to the anatase dominance at the grassy part of the TiO2 NTs as well as the higher surface area the structure may have. This work provides a novel insight into the photocatalytic reduction of Cr(VI) on grassy anatase TiO2 NTs.
    Matched MeSH terms: Hydrogen Peroxide
  9. Photoelectrochemical behaviour of uniform growth TiO2 nanotubes via bubble blowing synthesised in ethylene glycol with hydrogen peroxide
    Lai CW, Sreekantan S, Lockman Z
    J Nanosci Nanotechnol, 2012 May;12(5):4057-66.
    PMID: 22852347
    Uniformly sized TiO2 nanotubes with high aspect ratios were synthesised on a large substrate (100 mm x 100 mm) via the bubbling system through anodisation of Ti in ethylene glycol containing 5 wt% NH4F and 5 wt% H2O2. The benefits of bubbling system in producing uniformly sized TiO2 nanotubes throughout the Ti foil are illustrated. Moreover, the effects of applied voltage and fluoride content on the resulting nanotubes were also considered. Such uniform sized TiO2 nanotubes are a key to produce hydrogen efficiently using PEC cell. The results show higher photocurrent responses for the high aspect ratio, uniform TiO2 nanotubes because of excellent interfacial electron transfer.
    Matched MeSH terms: Hydrogen Peroxide
  10. Visible light photoelectrochemical performance of W-loaded TiO2 nanotube arrays: structural properties
    Lai CW, Sreekantan S
    J Nanosci Nanotechnol, 2012 Apr;12(4):3170-4.
    PMID: 22849082
    Well aligned TiO2 nanotubes were successfully synthesized by anodization of Ti foil at 60 V in a fluorinated bath comprised of ethylene glycol with 5 wt% of NH4F and 5 wt% of H2O2. In order to enhance the visible light absorption and photoelectrochemical response of pure TiO2 nanotube arrays, a mixed oxide system (W-TiO2) was investigated. W-TiO2 nanotube arrays were prepared using radio-frequency (RF) sputtering to incorporate the W into the lattice of TiO2 nanotube arrays. The W atoms occupy the substitutional position within the vacancies of TiO2 nanotube arrays. The as-anodized TiO2 is amorphous in nature while the annealed TiO2 is anatase phase. The mixed oxide (W-TiO2) system in suitable TiO2 phase plays important roles in efficient electron transfers due to the reduction in electron-hole recombination. In this article, the effect of the sputtered W into the as-anodized/annealed TiO2 nanotube arrays on the photoelectrochemical response was presented.
    Matched MeSH terms: Hydrogen Peroxide
  11. Applicability of TiO2(B) nanosheets@hydrochar composites for adsorption of tetracycline (TC) from contaminated water
    Mengting Z, Kurniawan TA, Avtar R, Othman MHD, Ouyang T, Yujia H, et al.
    J Hazard Mater, 2021 03 05;405:123999.
    PMID: 33288338 DOI: 10.1016/j.jhazmat.2020.123999
    We test the feasibility of TiO2(B)@carbon composites as adsorbents, derived from wheat straws, for tetracycline (TC) adsorption from aqueous solutions. Hydrochar (HC), biochar (BC), and hydrochar-derived pyrolysis char (HDPC) are synthesized hydrothermally from the waste and then functionalized with TiO2(B), named as 'Composite-1', 'Composite-2', and 'Composite-3', respectively. A higher loading of TiO2(B) into the HC was also synthesized for comparison, named as 'Composite-4'. To compare their physico-chemical changes before and after surface modification, the composites are characterized using FESEM-EDS, XRD, BET, FRTEM, and FTIR. The effects of H2O2 addition on TC removal are investigated. Adsorption kinetics and isotherms of TC removal are studied, while TC adsorption mechanisms are elaborated. We found that the Composite-4 has the highest TC removal (93%) at pH 7, 1 g/L of dose, and 4 h of reaction time at 50 mg/L of TC after adding H2O2 (10 mM). The TC adsorption capacities of the Composite-1 and Composite-4 are 40.65 and 49.26 mg/g, respectively. The TC removal by the Composite-1 follows the pseudo-second order. Overall, this suggests that converting the wheat straw into HC and then functionalizing its surface with TiO2(B) as a composite has added values to the waste as an adsorbent for wastewater treatment.
    Matched MeSH terms: Hydrogen Peroxide
  12. DNAzyme Sensor Uses Chemiluminescence Resonance Energy Transfer for Rapid, Portable, and Ratiometric Detection of Metal Ions
    Zheng J, Wai JL, Lake RJ, New SY, He Z, Lu Y
    Anal Chem, 2021 08 10;93(31):10834-10840.
    PMID: 34310132 DOI: 10.1021/acs.analchem.1c01077
    DNAzymes have emerged as an important class of sensors for a wide variety of metal ions, with florescence DNAzyme sensors as the most widely used in different sensing and imaging applications because of their fast response time, high signal intensity, and high sensitivity. However, the requirements of an external excitation light source and its associated power increase the cost and size of the fluorometer, making it difficult to be used for portable detections. To overcome these limitations, we report herein a DNAzyme sensor that relies on chemiluminescence resonance energy transfer (CRET) without the need for external light. The sensor is constructed by combining the functional motifs from both Pb2+-dependent 8-17 DNAzyme conjugated to fluorescein (FAM) and hemin/G-quadruplex that mimics horseradish peroxidase to catalyze the oxidation of luminol by H2O2 to yield chemiluminescence. In the absence of Pb2+, the hybridization between the enzyme and substrate strands bring the FAM and hemin/G-quadruplex in close proximity, resulting in CRET. The presence of Pb2+ ions can drive the cleavage on the substrate strand, resulting in a sharp decrease in the melting temperature of hybridization and thus separation of the FAM from hemin/G-quadruplex. The liberated CRET pair causes a ratiometric increase in the donor's fluorescent signal and a decrease in the acceptor signal. Using this method, Pb2+ ions have been measured rapidly (<15 min) with a low limit of detection at 5 nM. By removing the requirement of exogenous light excitation, we have demonstrated a simple and portable detection using a smartphone, making the DNAzyme-CRET system suitable for field tests of lake water. Since DNAzymes selective for other metal ions or targets, such as bacteria, can be obtained using in vitro selection, the method reported here opens a new avenue for rapid, portable, and ratiometric detection of many targets in environmental monitoring, food safety, and medical diagnostics.
    Matched MeSH terms: Hydrogen Peroxide
  13. Activated electric arc furnace slag as an effective and reusable Fenton-like catalyst for the photodegradation of methylene blue and acid blue 29
    Nasuha N, Ismail S, Hameed BH
    J Environ Manage, 2017 Jul 01;196:323-329.
    PMID: 28314221 DOI: 10.1016/j.jenvman.2017.02.070
    In this work, an activated electric arc furnace slag (A-EAFS) was investigated as an effective Fenton catalyst for the photodegradation of methylene blue (MB) and acid blue 29 (AB29). Fourier transform infrared spectroscopy and UV-visible absorption analyses indicated that A-EAFS offers additional Fe3O4 because of the changes in the iron oxide phase and the favorable response to visible light. It has been found that the highest degradation efficiency can reach up to 94% for MB under optimal conditions of 1 g L-1 of A-EAFS, 20 mM H2O2, and pH 3. The optimal conditions for AB29 were 0.1 g L-1 A-EAFS, 4 mM H2O2, and pH 3 to reach 98% degradation efficiency. Visible light enhanced the degradation of both dyes. In addition, A-EAFS, could be easily separated magnetically, exhibited good chemical stability after seven successive photodegradation cycles.
    Matched MeSH terms: Hydrogen Peroxide
  14. Fulltext DNA damaging effect of selected salted and fermented food products against Chang liver cell
    Razinah Sharif, Ahmad Rohi Ghazali, Nor Fadilah Rajab
    Jurnal Sains Kesihatan Malaysia, 2007;5(2):63-77.
    MyJurnal
    DNA damaging effect of the salted and fermented food products (salted fishes, dried shrimps and shrimp pastes) collected from three different locations in Malacca namely Pantai Puteri, Batang Tiga and Kelemak on the DNA of the Chang liver cells were evaluated via Alkaline Comet Assay. Treatment at 62.5 mg/ml following 24 hours of incubation was used based on the preliminary cytotoxicity data. Percentage of damage to the DNA was calculated using software for scoring based on the tail moment and tail intensity (severity of the DNA damage). Hydrogen peroxide was used as positive control at 0.1 mM following 30 minutes of incubation in 4 C. The results showed that the methanol extracts of shrimp pastes and salted fish from Pantai Puteri, exhibited a higher DNA damage (shrimp pastes - TM - 8.33 ± 2.19; TI - 31.67 ± 5.84, salted fishes - TM - 2.25 ± 0.86; TI - 9.25 ± 1.55) and were expressed as (shrimp pastes) 56.66 ± 8.74% of DNA damage and methanol salted fish extracts from the same location showed 13.00 ± 2.84% of the DNA damage on Chang liver cells compared to the other extracts. Values for methanol extract of shrimp pastes from Pantai Puteri were comparable to the positive control - Hydrogen peroxide (TM- 9.50 ± 1.50; TI - 30.50 ± 2.50). On the other hand, aqueous salted fishes extract from Pantai Puteri (TM - 1.33 ± 0.42; TI - 8.67 ± 2.42) and shrimp pastes extracts from Kelemak (methanol extract - TM -1.75 ± 0.15; TI -7.50 ± 0.50, aqueous extract - TM - 1.00 ± 0.00; TI - 5.00 ± 0.00) showed slightly high value for tail moment and tail intensity as compared to negative control (TM - 0.29 ± 0.05; TI - 2.50 ± 0.29). Values for methanol extracts of shrimp pastes from Pantai Puteri were comparable to the positive control (TM- 9.50 ± 1.50; TI - 30.50 ± 2.50). In conclusion, our results demonstrate genotoxic damage induced by few salted and fermented food extracts in Chang liver cell.
    Matched MeSH terms: Hydrogen Peroxide
  15. Fulltext Simple modification measurement of photodegradability of polymers by using photo-induced chemiluminescence technique
    Siti Farhana Zakaria, Millington, Keith R.
    Scientific Research Journal, 2013;10(2):0-0.
    MyJurnal
    Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.
    Matched MeSH terms: Hydrogen Peroxide
  16. Fulltext Optimization of modified fenton (fegac/h2o2) pretreatment of antibiotics
    Augustine Chioma Affam, Malay Chaudhuri, Shamsul Rahman Mohammed Kutty
    Pertanika Journal of Science & Technology, 2014;22(1):239-254.
    MyJurnal
    The study examined modified Fenton (FeGAC/H2O2) pretreatment of the antibiotics amoxicillin and cloxacillin in aqueous solution for biological treatment. The treatment was optimized by the response surface methodology (RSM). The optimum operating conditions at pH3 were H2O2/COD molar ratio 2.0, FeGAC dose 3.5 g/L and reaction time 90 min for 87.53% removal of COD, 78.01% removal of TOC, and 98.24% removal of NH3-N. Biodegradability (BOD5/COD ratio) improved from zero to 0.36, indicating the effluent was amenable to biological treatment. Meanwhile, FTIR spectra indicated degradation of the antibiotics. Compared with Fenton or photo-Fenton, modified Fenton (FeGAC/H2O2) was more effective in the pre-treatment of the antibiotics amoxicillin and cloxacillin in aqueous solution for biological treatment.
    Matched MeSH terms: Hydrogen Peroxide
  17. Advanced Oxidation Processes: Process Mechanisms, Affecting Parameters and Landfill Leachate Treatment
    Su-Huan K, Fahmi MR, Abidin CZA, Soon-An O
    Water Environ Res, 2016 Nov 01;88(11):2047-2058.
    PMID: 28661323 DOI: 10.2175/106143016X14733681695285
      Advanced oxidation processes (AOPs) are of special interest in treating landfill leachate as they are the most promising procedures to degrade recalcitrant compounds and improve the biodegradability of wastewater. This paper aims to refresh the information base of AOPs and to discover the research gaps of AOPs in landfill leachate treatment. A brief overview of mechanisms involving in AOPs including ozone-based AOPs, hydrogen peroxide-based AOPs and persulfate-based AOPs are presented, and the parameters affecting AOPs are elaborated. Particularly, the advancement of AOPs in landfill leachate treatment is compared and discussed. Landfill leachate characterization prior to method selection and method optimization prior to treatment are necessary, as the performance and practicability of AOPs are influenced by leachate matrixes and treatment cost. More studies concerning the scavenging effects of leachate matrixes towards AOPs, as well as the persulfate-based AOPs in landfill leachate treatment, are necessary in the future.
    Matched MeSH terms: Hydrogen Peroxide
  18. Pyrus pyrifolia fruit peel as sustainable source for spherical and porous network based nanocellulose synthesis via one-pot hydrolysis system
    Chen YW, Hasanulbasori MA, Chiat PF, Lee HV
    Int J Biol Macromol, 2019 Feb 15;123:1305-1319.
    PMID: 30292586 DOI: 10.1016/j.ijbiomac.2018.10.013
    In the present study, we attempted revalorization of pear (Pyrus pyrifolia L.) peel residue into high value-added nanomaterials. A green and facile one-pot isolation procedure was designed to simplify the isolation process of nanocellulose directly from pear peel residue. The one-pot approach employed in this work is interesting as the reaction involved less harmful chemicals usage and non-multiple steps. The reaction was carried out by adding hydrogen peroxide as an oxidant and chromium (III) nitrate as catalyst in the acidic medium under mild process conditions. FTIR spectroscopy proved that the pear peel derived nanocellulose was purely cellulose phases without the presence of non-cellulosic layer. XRD study indicated that the isolated nanocellulose possessed of cellulose I polymorph with high crystallinity index of 85.7%. FESEM analysis clearly revealed that the considerable size reduction during one-pot process. Remarkably, TEM analysis revealed that the isolated nanocellulose consisted of network-liked nature and spherical shaped morphologies with high aspect ratio of 24.6. TGA showed nanocellulose has lower thermal stability compared to pear peel residue. This study provided a cost-effective method and straightforward one-pot process for fabrication of nanocellulose from pear peel residue. This is the first investigation on the nanocellulose extraction from pear fruit.
    Matched MeSH terms: Hydrogen Peroxide
  19. Hybrid liquid biphasic system for cell disruption and simultaneous lipid extraction from microalgae Chlorella sorokiniana CY-1 for biofuel production
    Yew GY, Chew KW, Malek MA, Ho YC, Chen WH, Ling TC, et al.
    Biotechnol Biofuels, 2019;12:252.
    PMID: 31666807 DOI: 10.1186/s13068-019-1591-8
    Background: The extraction of lipids from microalgae requires a pretreatment process to break the cell wall and subsequent extraction processes to obtain the lipids for biofuels production. The multistep operation tends to incur high costs and are energy intensive due to longer process operations. This research work applies the combination of radicals from hydrogen peroxide with an organic solvent as a chemical pretreatment method for disrupting the cell wall of microalgae and simultaneously extracting lipids from the biomass in a one-step biphasic solution.

    Result: Several parameters which can affect the biphasic system were analyzed: contact time, volume of solvent, volume ratio, type of organic solvent, biomass amount and concentration of solvents, to extract the highest amount of lipids from microalgae. The results were optimized and up to 83.5% of lipid recovery yield and 94.6% of enhancement was successfully achieved. The results obtain from GC-FID were similar to the analysis of triglyceride lipid standard.

    Conclusion: The profound hybrid biphasic system shows great potential to radically disrupt the cell wall of microalgae and instantaneously extract lipids in a single-step approach. The lipids extracted were tested to for its comparability to biodiesel performance.

    Matched MeSH terms: Hydrogen Peroxide
  20. Fulltext Degradation of congo red dye in aqueous solution by using advanced oxidation processes
    Alya Nadhira Nasron, Ninna Sakina Azman, Nor Syaidatul Syafiqah Mohd Rashid, Nur Rahimah Said
    Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2018;6(2):1-11.
    MyJurnal
    Degradation of azo dyes by using advanced oxidation processes (AOPs) was conducted. In this approach, different AOPs, which are Fenton process and titanium dioxide (TiO2) catalyst, were examined and compared for the degradation of an azo dye (i.e., Congo red dye). The sample was tested under UV light and the experiment was conducted for 90 min with 15 min interval. The degradation rate of dye was determined using UV-Vis spectrophotometry. The effect of several parameters on the degradation process such as the concentration of metal ions (Fe2+, Cu2+, and Mn2+) as the catalyst in Fenton process, the concentration of hydrogen peroxide (H2O2), the mass of TiO2, and pH value of the dye solution were investigated. The initial Congo red concentration used for both techniques was 5 ppm. The results showed that the percentage degradation followed the sequence of H2O2/Fe2+/UV, H2O2/Cu2+/UV, H2O2/Mn2+/UV, and TiO2/UV. The best operating conditions for H2O2/Fe2+/UV were pH 3, 0.2 M concentration of H2O2, and 0.02 M concentration of metal ion in 15 min, which achieved 99.92% degradation of dye. The Fourier transform infrared (FTIR) spectrum showed the absence of azo bond (N=N) peak after degradation process, which indicates the successful cleavage of azo bond in the chemical structure of Congo red.
    Matched MeSH terms: Hydrogen Peroxide
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