Nanoscale Zero-valent Iron For Removal Research Articles

Efficient peroxymonosulfate activation by nanoscale zerovalent iron for removal of sulfadiazine and sulfadiazine resistance bacteria: Sulfidated modification or not

Whether it’s necessary to extra chemical synthesis steps to modify nZVI in peroxymonosulfate (PMS) activation process are worth to further investigation. The 56 mg/L nZVI/153.65 mg/L PMS and 56 mg/L sulfidated nZVI (S-nZVI) (S/Fe molar ratio = 1:5)/153.65 mg/L PMS) processes could effectively attain 97.7% (with kobs of 3.7817 min−1) and 97.0% (with kobs of 3.4966 min−1) of the degradation of 20 mg/L sulfadiazine (SDZ) in 1 min, respectively. The nZVI/PMS system could quickly achieve 85.5% degradation of 20 mg/L SDZ in 1 min and effectively inactivate 99.99% of coexisting Pseudomonas. HLS-6 (5.81-log) in 30 min. Electron paramagnetic resonance tests and radical quenching experiments determined SO4•−, HO•, 1O2 and O2•− were responsible for SDZ degradation. The nZVI/PMS system could still achieve the satisfactory degradation efficiency of SDZ under the influence of humic acid (exceeded 96.1%), common anions (exceeded 67.3%), synthetic wastewater effluent (exceeded 90.7%) and real wastewater effluent (exceeded 78.7%). The high degradation efficiency of tetracycline (exceeded 98.9%) and five common disinfectants (exceeded 96.3%) confirmed the applicability of the two systems for pollutants removal. It’s no necessary to extra chemical synthesis steps to modify nZVI for PMS activation to remove both chemical and biological pollutants.

Investigation of a modified metal-organic framework UiO-66 with nanoscale zero-valent iron for removal of uranium (VI) from aqueous solution.

A novel composite material (nZVI/UiO-66) of nanoscale zero-valent iron (nZVI) with a functionalized metal-organic framework was synthesized by this study via a coprecipitation method, which was used for the efficient removal of U(VI) in the aqueous solution. The nZVI/UiO-66 had an excellent removal capacity of 404.86mgg-1 with an initial U(VI) concentration of 80mgL-1, 313K and pH = 6. The transmission electron microscopy (TEM) revealed that nZVI particles were inhomogeneously distributed on the surface of UiO-66. The analysis by the X-ray diffraction (XRD) has further illustrated that the introduction of nZVI did not change the structure of UiO-66. The adsorption process closely followed the pseudo-second-order kinetic and the Freundlich isotherm model. The removal process of U(VI) by nZVI/UiO-66 was spontaneous and endothermic. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses have illustrated that the mechanism was mainly related to adsorption of U(VI) from UiO-66 and reduction of U(VI) by nZVI. The Zr-O bonds were shown to play a vital role in the uranium removal. nZVI/UiO-66 could be recycled. The uptake rate could be maintained at around 80% after 5cycles of use. Therefore, these results manifested that the nZVI/UiO-66 is a promising sorbent for the efficient and selective removal of U(VI) in radioactive wastewaters.

Use of Kaolin-supported Nano-scale Zero-valent Iron for Removal of Remazol Brilliant Blue R from Aqueous Solution

Bu çalışmada, kaolin destekli nano boyutlu sıfır değerlikli demir (K-nZVI) partikülleri kaolin varlığında borhidrür indirgeme metodu ile sentezlenmiş ve sulu çözeltiden Remazol Brilliant Blue R (RBBR) gideriminde kullanılmıştır. RBBR gideriminde çözelti başlangıç pH’ı, K-nZVI dozajı, temas süresi ve başlangıç boyar madde konsantrasyonunun etkisi değerlendirilmiştir. Giderim veriminin pH’a bağlı olduğu tespit edilmiş ve RBBR’nin maksimum giderim verimi pH 3’te gerçekleşmiştir. 0.3-1.0 g L-1 dozaj aralığında K-nZVI dozajının artışı ile RBBR giderim verimi artmıştır. 60 dakikalık temas süresinde dengeye ulaşılmıştır. Başlangıç boyar madde konsantrasyonun artışı ile giderim verimi azalmıştır. Çalışmada, deneysel verilerin Langmuir ve Freundlich izoterm modellere uygunluğu da araştırılmış ve bu modellere ait parametreler hesaplanmıştır. K-nZVI ile RBBR adsorpsiyonun hem Langmuir hem de Freundlich izoterme uygun olduğu tespit edilmiştir. Maksimum adsorpsiyon kapasitesi 200 mg g-1 olarak belirlenmiştir.

Wheat straw biochar-supported nanoscale zerovalent iron for removal of trichloroethylene from groundwater.

This study synthesized the wheat straw biochar-supported nanoscale zerovalent iron (BC-nZVI) via in-situ reduction with NaBH4 and biochar pyrolyzed at 600°C. Wheat straw biochar, as a carrier, significantly enhanced the removal of trichloroethylene (TCE) by nZVI. The pseudo-first-order rate constant of TCE removal by BC-nZVI (1.079 h−1) within 260 min was 1.4 times higher and 539.5 times higher than that of biochar and nZVI, respectively. TCE was 79% dechlorinated by BC-nZVI within 15 h, but only 11% dechlorinated by unsupported nZVI, and no TCE dechlorination occurred with unmodified biochar. Weakly acidic solution (pH 5.7–6.8) significantly enhanced the dechlorination of TCE. Chloride enhanced the removal of TCE, while SO42−, HCO3− and NO3− all inhibited it. Humic acid (HA) inhibited BC-nZVI reactivity, but the inhibition decreased slightly as the concentration of HA increased from 40 mg∙L-1 to 80 mg∙L-1, which was due to the electron shutting by HA aggregates. Results suggest that BC-nZVI was promising for remediation of TCE contaminated groundwater.

Novel synthesis of carbon spheres supported nanoscale zero-valent iron for removal of metronidazole

For the first time, carbon spheres-supported nanoscale zero-valent iron (NZVI/CSs) were successfully synthesized as functionalized composite via liquid phase reduction method and adopted for removal of a typical antibiotic, metronidazole (MNZ), from wastewater. The resultant composite (NZVI/CSs) exhibit higher reactivity, excellent stability, enhanced dispersion, and improved longevity over the reaction course due to the presence of the charged carboxyl groups and hydroxyl groups on the surfaces of CSs. The results show that 94.18% of MNZ was removed using NZVI/CSs after 6min, while only 36.45% and 8.78% of MNZ were removed using NZVI and CSs, respectively. The galvanic cell system between NZVI and CSs was essential for enhancing MNZ reduction in aqueous solution. Furthermore, the new findings include kinetics for MNZ removal by NZVI/CSs composite could be well expressed by a revised two-parameter pseudo-first-order model. Finally, the possible degradation mechanism was proposed, which was based on the analysis of degraded products by high performance liquid chromatography–mass spectrometry (HPLC–MS). Different important factors impacting on MNZ removal (including mass ratio of NZVI to CSs, initial concentration, pH value and solution temperature) were investigated as well. Overall, this study provides a promising alternative material and environmental pollution management option for antibiotic wastewater treatment.

Illite-supported nanoscale zero-valent iron for removal of 238U from aqueous solution: characterization, reactivity and mechanism

In this work, illite was used to support zero-valent iron nanoparticles to remove 238U in aqueous solutions. Compared to nZVI, I-nZVI shows high stability and removal efficiency. Removal process of U on I-nZVI can be concluded into four stages in illite dominated zone, Fe0 released zone, ferrous dominated zone and reaction equilibrium zone. The study shows that illite is a good dispersant and stabilizer which decreases the aggregation of nZVI and improves the activity of Fe0. Removal capacity of U on I-nZVI achieves 1.79 µg/mg. I-nZVI is an efficient and promising remediation material for waste-soluble uranium compounds.

Aluminum Pillared Palygorskite-Supported Nanoscale Zero-Valent Iron for Removal of Cu(II), Ni(II) From Aqueous Solution

A new composite clay, aluminum pillared palygorskite-supported nanoscale zero-valent iron (Al–P-nZVI), was prepared by reducing ferric ion (FeCl3.6H2O) to Fe0 with sodium borohydride (NaBH4) on aluminum pillared palygorskite, in order to improve metal ions adsorption capacities of palygorskite and reduce nanoscale zero-valent iron reunion. The composite clay was characterized by FTIR, TEM and XRD spectra. Batch isothermal equilibrium adsorption experiments were conducted to evaluate the clay adsorbent for the removal of Cu(II) and Ni(II) from water. The effects of pH, shaking time on adsorption capacity were also investigated. The pseudo-second-order model was relatively suitable for describing the reaction process. The equilibrium adsorption data were fitted to Langmuir adsorption models. The maximum adsorption capacities of aluminum pillared palygorskite-supported nanoscale zero-valent iron sorbent as obtained from Langmuir adsorption isotherm were found to be 787 and 704 mg g−1 for Cu(II) and Ni(II), respectively. A comparison of the results of the present investigation with those reported in the literature showed that Al–P-nZVI exhibits greater adsorption capacity for Cu(II)and Ni(II). These results demonstrated that Al–P-nZVI could potentially be used as an effective material for environmental remediation.

Montmorillonite-supported nanoscale zero-valent iron for removal of arsenic from aqueous solution: Kinetics and mechanism

Montmorillonite-supported nanoscale zero-valent iron (Mt-nZVI) has been synthesized to remove inorganic arsenic (As) from aqueous solutions. BET, SEM, EDX, XRD and XPS were used to characterize the clay-supported material which consists mainly of core shell Fe(0) structure with an outer oxide/hydroxide shell. The dispersion of nZVI onto montmorillonite was found to be increased with decreasing tendency to agglomerate into larger particles. Batch experiments revealed that adsorption kinetics followed pseudo-second order rate equation with high affinity towards both As(III) and As(V) over a wide pH range (4–8) which was decreased at pH>9. The maximum adsorption capacity calculated from the Langmuir adsorption isotherm was found to be 59.9 and 45.5mgg−1 for As(III) and As(V) respectively at pH 7.0. Although the presence of competing anions like SO42-, HCO3- and NO3- did not show pronounced effect, PO43- had an inhibitory action on the adsorption. The XPS analyses of As-reacted Mt-nZVI indicated the occurrence of surface catalyzed oxidation of As(III) to As(V). The possible regeneration using 0.1M NaOH and performance of Mt-nZVI was investigated by repeating adsorption-elution process. This study has great significance for demonstrating Mt-nZVI as potential adsorbent to reduce elevated levels of As in groundwater.

Cation exchange resin supported nanoscale zero-valent iron for removal of phosphorus in rainwater runoff

Self-made cation exchange resin supported nanoscale zero-valent iron (R-nZVI) was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial concentration of 0.72 mg·L−1 phosphorus when the dosage of R-nZVI is 8 g per liter rainwater, while only 26% of phosphorus was removed when using cation exchange resin without supported nanoscale zero-valent iron under the same condition. The adsorption capacity of R-nZVI increased up to 185 times of that of the cation exchange resin at a saturated equilibrium phosphorous concentration of 0.42 mg·L−1. Various techniques were implemented to characterize the R-nZVI and explore the mechanism of its removal of phosphate. Scanning electron microscopy (SEM) indicated that new crystal had been formed on the surface of R-nZVI. The result from inductive coupled plasma (ICP) indicated that 2.1% of nZVI was loaded on the support material. The specific surface area was increased after the load of nanoscale zero-valent iron (nZVI), according to the measurement of BET-N2 method. The result of specific surface area analysis also proved that phosphorus was removed mainly through chemical adsorption process. X-ray photoelectron spectroscopy (XPS) analysis showed that the new product obtained from chemical reaction between phosphate and iron was ferrous phosphate.

Kaolinite-supported nanoscale zero-valent iron for removal of Pb 2+ from aqueous solution: Reactivity, characterization and mechanism

The use of nanoscale zero-valent iron (nZVI) to remediate contaminated groundwater is limited due to its lack of durability and mechanical strength. To address this issue, 20% (w/w) nZVI was loaded onto kaolinite as a support material (K-nZVI). More than 96% of Pb 2+ was removed from aqueous solution using K-nZVI at an initial condition of 500 mg/L Pb 2+ within 30 min under the conditions of 10 g/L of K-nZVI, pH 5.10 and a temperature of 30 °C. To understand the mechanism of removal of Pb 2+, various techniques were implemented to characterize K-nZVI. Scanning electron microscopy (SEM) indicated that K-nZVI had a suitable dispersive state with a lower aggregation, where the mean specific surface area and average particle size as determined by the BET-N 2 method and X-ray diffraction (XRD), were 26.11 m 2/g and 44.3 nm, respectively. The results obtained from XRD, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated that a small number of iron oxides formed on the surface of K-nZVI, suggesting that free Pb 2+ was adsorbed onto K-nZVI and subsequently reduced to Pb 0.