scholarly journals Degradation Reactive Black 5 dye from aqueous solutions using ozonation with pumices and pumices modified by nanoscale zero valent iron (nZVI)

2020 ◽  
Keyword(s):  
Batch Reactor ◽  
Oxidation Mechanism ◽  
Zero Valent Iron ◽  
Radical Mechanism ◽  
Main Role ◽  
Reactive Black 5 ◽  
Direct Oxidation ◽  
Solution Ph ◽  
Nanoscale Zero Valent Iron ◽  
Textile Industries

<p>Reactive Black 5 (RB5) dyes are a dye widely used in textile industries. The nanocatalytic ozonation of RB5 solution in the presence of pumice modified with nanoscale zero valent iron (nZVI) catalysts and pumice raw investigated in a laboratory scale batch reactor. The effects of solution pH (3-11), reaction time, pumice dosage (10, 15 and 20 g/L) and COD removal were evaluated. Natural mineral raw pumice and pumice-nZVI was used directly in nanocatalytic ozonation of dye of RB5 solution. Compared with raw pumice, pumice-nZVI into the ozonation reactor greatly accelerated the rate of RB5 degradation. The results indicate that with increasing (pH, and pumice dosage) increased rate RB5 degradation. Molecular ozone direct oxidation mechanism was proved in nanocatalytic ozonation with pumice, and hydroxyl radical mechanism was demonstrated to play a main role in nanocatalytic ozonation with nZVI.</p>

scholarly journals Effect of structural differences of pumice on synthesis of pumice-supported nFe0: removal of Cr (VI) from water

2021 ◽  
Vol 11 (7) ◽  
Author(s):  
Bilsen Tural ◽  
Erdal Ertaş ◽  
Mehmet Güzel ◽  
Servet Tural
Keyword(s):  
Iron Content ◽  
Second Order ◽  
Zero Valent Iron ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Support Material ◽  
Solution Ph ◽  
Nanoscale Zero Valent Iron ◽  
Pseudo Second Order

AbstractIn this study, pumice from different regions of Turkey (Diyarbakir, Southeast Turkey and Bitlis, East Turkey) has been supplied and used as supporting material for nanoscale zero-valent iron (nFe0). Native Bitlis pumice (NBP)-supported nanoscale zero-valent iron (BP-nFe0) and native Diyarbakir pumice (NDP)-supported nanoscale zero-value iron (DP-nFe0) were synthesized under the same conditions. Native pumice (NDP, NBP) and pumice-supported nFe0 (DP-nFe0 and BP-nFe0) adsorbents were morphologically and structurally characterized by SEM, EDX, XRF and BET. When using NBP as support material, the iron content of the BP-nFe0 increased 1.9-fold from 1.99 to 3.83%. However, iron content of NDP (2.08%) increased approximately 29 times after it is used as a support material in synthesis of DP-nFe0 (60%). The removal potential of native pumice (NBP and NDP) and iron-modified pumice (BP-nFe0 and DP-nFe0) samples was investigated to remove Cr(VI) ions. The parameters of solution pH, initial metal concentration, contact time and the amount of adsorbent in the removal of chromium (VI) ions were investigated. Langmuir, Freundlich, Temkin, Dubinin–Radushkevich and Jovanovic isotherm models were used to evaluate the adsorption equilibrium data. The equilibrium adsorption was found so as to be well described by the Langmuir isotherm model for all the adsorbents studied. The maximum adsorption capacity of Cr(VI) ions for NDP, NBP, DP-nFe0 and BP-nFe0 was 10.82, 14.30, 161.29 and 17.39 mg/g, respectively. The rate of Cr(VI) removal was subjected to kinetic analysis using pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich models. Kinetic studies suggest that adsorption of NDP, NBP, DP-nFe0 and BP-nFe0 described more favorably by the pseudo-second-order kinetic model. The results showed that NDP is a much better support material for nFe0 when compared to NBP.

scholarly journals Limits of Versatility of Versatile Peroxidase

2016 ◽  
Vol 82 (14) ◽  
pp. 4070-4080 ◽  
Author(s):  
Doriv Knop ◽  
Dana Levinson ◽  
Arik Makovitzki ◽  
Avi Agami ◽  
Elad Lerer ◽  
...  
Keyword(s):  
Active Site ◽  
Aromatic Compounds ◽  
Pleurotus Ostreatus ◽  
Active Sites ◽  
Oxidation Mechanism ◽  
White Rot ◽  
White Rot Fungus ◽  
Reactive Black 5 ◽  
Direct Oxidation ◽  
Content Type

ABSTRACTAlthough Mn2+is the most abundant substrate of versatile peroxidases (VPs), repression ofPleurotus ostreatusvp1expression occurred in Mn2+-sufficient medium. This seems to be a biological contradiction. The aim of this study was to explore the mechanism of direct oxidation by VP1 under Mn2+-deficient conditions, as it was found to be the predominant enzyme during fungal growth in the presence of synthetic and natural substrates. The native VP1 was purified and characterized using three substrates, Mn2+, Orange II (OII), and Reactive Black 5 (RB5), each oxidized by a different active site in the enzyme. While the pH optimum for Mn2+oxidation is 5, the optimum pH for direct oxidation of both dyes was found to be 3. Indeed, effectivein vivodecolorization occurred in media without addition of Mn2+only under acidic conditions. We have determined that Mn2+inhibitsin vitrothe direct oxidation of both OII and RB5 while RB5 stabilizes both Mn2+and OII oxidation. Furthermore, OII was found to inhibit the oxidation of both Mn2+and RB5. In addition, we could demonstrate that VP1 can cleave OII in two different modes. Under Mn2+-mediated oxidation conditions, VP1 was able to cleave the azo bond only in asymmetric mode, while under the optimum conditions for direct oxidation (absence of Mn2+at pH 3) both symmetric and asymmetric cleavages occurred. We concluded that the oxidation mechanism of aromatic compounds by VP1 is controlled by Mn2+and pH levels both in the growth medium and in the reaction mixture.IMPORTANCEVP1 is a member of the ligninolytic heme peroxidase gene family of the white rot fungusPleurotus ostreatusand plays a fundamental role in biodegradation. This enzyme exhibits a versatile nature, as it can oxidize different substrates under altered environmental conditions. VPs are highly interesting enzymes due to the fact that they contain unique active sites that are responsible for direct oxidation of various aromatic compounds, including lignin, in addition to the well-known Mn2+binding active site. This study demonstrates the limits of versatility ofP. ostreatusVP1, which harbors multiple active sites, exhibiting a broad range of enzymatic activities, but they perform differently under distinct conditions. The versatility ofP. ostreatusand its enzymes is an advantageous factor in the fungal ability to adapt to changing environments. This trait expands the possibilities for the potential utilization ofP. ostreatusand other white rot fungi.

scholarly journals Removal of Nitrate by Bimetallic Copper-nanoscale Zero-valent Iron (Cu-nZVI): Using 2k Full Factorial Design

2014 ◽  
pp. 15-24 ◽  
Author(s):  
Nalinee Krasae ◽  
Kitirote Wantala ◽  
Puek Tantriratna ◽  
Nurak Grisdanurak
Keyword(s):  
Factorial Design ◽  
Batch Reactor ◽  
Nitrate Removal ◽  
Full Factorial Design ◽  
Zero Valent Iron ◽  
Impregnation Method ◽  
Nanoscale Zero Valent Iron ◽  
Acidic Conditions ◽  
Neutral Conditions ◽  
Full Factorial

Enhanced nitrate reduction of nanoscale zero valent iron (nZVI) by Cu prepared by impregnation method was studied in this work. Using a full factorial design, the performance of nZVI with and without Cu on surface in acidic and neutral conditions was investigated. Static batch reactor was selected in this study to investigate the effects of the independent variables such as catalysts (nZVI with and without Cu), initial pH of solutions (3, 7), and reaction times (10, 30 min). The results found that nitrate removal over Cu-nZVI was greater than that of nZVI by about 37% and 36% at pH 3 and pH 7 for 30 min, respectively. Both catalysts were effective in removing nitrate under acidic conditions (pH 3). Thus, this study concludes that nZVI can enhance the performance by Cu in nitrate removal. Moreover, acidic conditions were more effective than neutral conditions in removing nitrate.

Adsorption and advanced oxidation of diverse pharmaceuticals and personal care products (PPCPs) from water using highly efficient rGO–nZVI nanohybrids

2020 ◽  
Vol 6 (8) ◽  
pp. 2223-2238 ◽  
Author(s):  
Arvid Masud ◽  
Nita G. Chavez Soria ◽  
Diana S. Aga ◽  
Nirupam Aich
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Personal Care Products ◽  
Advanced Oxidation ◽  
Zero Valent Iron ◽  
Redox Activity ◽  
Personal Care ◽  
Adsorption Sites ◽  
Reduced Graphene ◽  
Nanoscale Zero Valent Iron

Reduced graphene oxide-nanoscale zero valent iron (rGO–nZVI) nanohybrid, with tunable adsorption sites of rGO and unique catalytic redox activity of nZVI, perform enhanced removal of diverse PPCPs from water.

scholarly journals Efficient Sequestration of Hexavalent Chromium by Graphene-Based Nanoscale Zero-Valent Iron Composite Coupled with Ultrasonic Pretreatment

2021 ◽  
Vol 18 (11) ◽  
pp. 5921
Author(s):  
Haiyan Song ◽  
Wei Liu ◽  
Fansheng Meng ◽  
Qi Yang ◽  
Niandong Guo
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Inhibitory Effect ◽  
Ultrasonic Cavitation ◽  
Zero Valent Iron ◽  
Ultrasonic Pretreatment ◽  
Nanoscale Zero Valent Iron ◽  
Passivation Layers ◽  
Initial Ph ◽  
Two Phases

Nanoscale zero-valent iron (nZVI) has attracted considerable attention for its potential to sequestrate and immobilize heavy metals such as Cr(VI) from an aqueous solution. However, nZVI can be easily oxidized and agglomerate, which strongly affects the removal efficiency. In this study, graphene-based nZVI (nZVI/rGO) composites coupled with ultrasonic (US) pretreatment were studied to solve the above problems and conduct the experiments of Cr(VI) removal from an aqueous solution. SEM-EDS, BET, XRD, and XPS were performed to analyze the morphology and structures of the composites. The findings showed that the removal efficiency of Cr(VI) in 30 min was increased from 45.84% on nZVI to 78.01% on nZVI/rGO and the removal process performed coupled with ultrasonic pretreatment could greatly shorten the reaction time to 15 min. Influencing factors such as the initial pH, temperature, initial Cr(VI) concentration, and co-existing anions were studied. The results showed that the initial pH was a principal factor. The presence of HPO42−, NO3−, and Cl− had a strong inhibitory effect on this process, while the presence of SO42− promoted the reactivity of nZVI/rGO. Combined with the above results, the process of Cr(VI) removal in US-nZVI/rGO system consisted of two phases: (1) The initial stage is dominated by solution reaction. Cr(VI) was reduced in the solution by Fe2+ caused by ultrasonic cavitation. (2) In the following processes, adsorption, reduction, and coprecipitation coexisted. The addition of rGO enhanced electron transportability weakened the influence of passivation layers and improved the dispersion of nZVI particles. Ultrasonic cavitation caused pores and corrosion at the passivation layers and fresh Fe0 core was exposed, which improved the reactivity of the composites.

scholarly journals Efficient activation of persulfate by calcium sulfate whisker supported nanoscale zero-valent iron for methyl orange removal

RSC Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 452-461
Author(s):  
Yi Han ◽  
Xian Zhou ◽  
Li Lei ◽  
Huiqun Sun ◽  
Zhiyuan Niu ◽  
...  
Keyword(s):  
Composite Material ◽  
Methyl Orange ◽  
Calcium Sulfate ◽  
Zero Valent Iron ◽  
Nanoscale Zero Valent Iron ◽  
Calcium Sulfate Whiskers ◽  
Calcium Sulfate Whisker

In order to improve the utilization of nanoscale zero-valent iron (nZVI) in activating persulfate (PS), a composite material of nZVI/CSW with nZVI supported on calcium sulfate whiskers (CSWs) was synthesized in this study.

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