Reductive degradation of perfluorinated compounds in water using Mg-aminoclay coated nanoscale zero valent iron

Arvaniti, Olga S.,Hwang, Yuhoon,Andersen, Henrik R.,Stasinakis, Athanasios S.,Thomaidis, Nikolaos S.,Aloupi, Maria Elsevier 2015 Chemical engineering journal Vol.262 No.-

<P><B>Abstract</B></P> <P>Perfluorinated compounds (PFCs) are extremely persistent micropollutants that are detected worldwide. We studied the removal of PFCs (perfluorooctanoic acid; PFOA, perfluorononanoic acid; PFNA, perfluorodecanoic acid; PFDA and perfluorooctane sulfonate; PFOS) from water by different types of nanoscale zero-valent iron (nZVI). Batch experiments showed that an iron dose of 1gL<SUP>−1</SUP> in the form of Mg-aminoclay (MgAC) coated nZVI, at an initial pH of 3.0 effectively removed 38–96% of individual PFCs. An increasing order of removal efficiency was observed of PFOA<PFNA<PFOS≈PFDA. Compared to this, PFCs removal was less than 27% using a commercial air stabilized nZVI or freshly synthesized uncoated nZVI, under the same experimental conditions. The effectiveness of PFCs removal by MgAC coated nZVI was further investigated at various initial pH, nZVI dosage, temperature and age of the nZVI. A maximum removal was observed for all PFCs with high nZVI concentration, freshly synthesized nZVI, low pH and low temperature. A mass balance experiment with PFOS in a higher concentration of nZVI revealed that the removal was due to both sorption and degradation. Fluoride production partially matched the observed degradation, while no organic byproducts were detected using LC–QTOF–MS.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Different nanosized zero valent iron (nZVI) types were tested for PFCs degradation. </LI> <LI> Only nZVI coated with a cationic surface modifier removed PFCs effectively. </LI> <LI> The order of PFCs degradability was PFOA<PFNA<PFOS≈PFDA. </LI> <LI> Low pH and temperature favored degradation of PFCs by surface modified nZVI. </LI> <LI> Fluoride formation confirmed PFCs degradation while partial sorption was observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Preparation of air stable nanoscale zero valent iron functionalized by ethylene glycol without inert condition

Ruiz-Torres, Claudio Adrian,Araujo-Martí,nez, René,Fernando,Martí,nez-Castañ,ó,n, Gabriel Alejandro,Morales-Sá,nchez, J. Elpidio,Guajardo-Pacheco, Jesú,s Mar& Elsevier 2018 Chemical Engineering Journal Vol.336 No.-

<P><B>Abstract</B></P> <P>The use of nanoscale zero-valent iron has been widely studied in recent years for potential application in environmental engineering, due to its affinity for a large number of contaminants, which may be in aqueous or solid phase, and for its abundance, which makes it an attractive tool for environmental remediation. However, there exist some variables in the production of nZVI that complicate the generation of the material, such as the complex methodologies of synthesis and the cost of inert conditions like nitrogen or argon atmosphere, which have the purpose of preventing the oxidation and reducing the instability of the material under ambient conditions. As a simple and economical synthesis methodology, this work presents an optimized method to synthesize functionalized nanoscale zero-valent iron (nZVI) using ethylene glycol (EG) without need for inert conditions. The coordination of iron ions during the nZVI-EG synthesis and the functionalization mechanism of the nanoparticles were identified by UV–Vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). Functionalized nZVI showed increased dispersibility due to the effects of steric repulsion between the grafted polymers. Ethylene glycol functionalized nZVI showed stability against oxidation during dry atmospheric condition, while significant oxidation was observed in the case of unfunctionalized nZVI. This result was also correlated with actual capacity for contaminant reduction. Therefore, the possibility was verified of using ethylene glycol in an effective surface modification method to prepare air stable nZVI for environmental remediation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Air-stable nZVI could be prepared by ethylene glycol without inert condition. </LI> <LI> Smaller and narrower size distribution could be obtained by functionalization. </LI> <LI> The nZVI-EG exhibited a protection effect against oxidation in oxic conditions. </LI> <LI> The reaction kinetics was not hindered by the organic functionalization agent EG. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Removal of hexavalent chromium ion from aqueous solution using nanoscale zero-valent iron particles immobilized on porous silica support prepared by polymer template method

장민채,박보영,이현승,김태영,김양수 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.10

Porous silica supported nanoscale zero-valent iron was prepared by a polymer template method in order to effectively remove a hexavalent chromium ion (Cr(VI)) in an aqueous solution. It did not show a deterioration of Cr(VI) removal efficiency, which could be caused by the surface oxidation and agglomeration of nanoscale zero-valent iron (NZVI) particles. Porous silica by the polymer template method showed quite unique structure, which we named as quasi-inverse opal silica (QIOS), and it showed high surface area (375.4m2/g) and fine pore size (76.5nm). NZVI immobilized on the surface of QIOS (NZVI@QIOS) was added to an aqueous Cr(VI) solution at 0.025g/L, and it showed over 96% Cr(VI) removal efficiency. Such a high removal efficiency of Cr(VI) was maintained over two weeks after preparation (92% after 16days). Morphology of porous silica supported nanoscale zero-valent iron was analyzed by TEM and FE-SEM. Identification of the reaction compounds produced by the reaction of Cr(VI) and zero-valent iron (Fe(0)) was made by the application of XPS.

나노영가철의 TCE 분해반응 시 지하수 용존물질의 영향

김태호(Tae Ho Kim),김홍석(Hong Seok Kim),이진용(Jin Yong Lee),천정용(Jeong Yong Cheon),이강근(Kang Kun Lee),황인성(In Seong Hwang) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.6

본 연구에서는 TCE 등의 유기오염물질로 오염된 현장의 지하수를 처리하기 위한 반응매질로써 나노영가철(nanoscale zero valent iron, NZVI)의 적용성을 평가하기 위해 수행되었다. 오염현장에서는 TCE 외에 음이온(NO₃-, Cl-, SO₄^2-, HCO₃-)과 자연유기물질(natural organic matter, NOM)이 검출되었으며 상업용 나노영가철(NANOFER 25, Nanorion)을 이용하여 모의, 현장 지하수를 처리하고 그 결과를 분석하였다. TCE만을 고려한 처리실험에서 25 g/L의 NANOFER 25는 1.8 mM TCE를 약 20시간에 95% 이상 처리하였으며(k = 0.15 hr-1), TCE 반복주입을 통해 평가한 NANOFER 25의 반응용량은 0.19 mmole TCE/g NZVI인 것으로 나타났다. 음이온은 개별 음이온의 농도는 반응성에 큰 영향을 주지 않았으나 4가지 음이온을 모두 포함하는 오염현장의 평균농도로 제조한 모의지하수처리 시 유사 1차속도상수(k)가 0.069 hr-1로 60% 감소하였으며 총 반응용량은 10% 감소하였다. 용존성 유기물(DOC)를 기준으로 한 유기물의 현장 평균농도에서는 반응속도상수가 0.025 hr-1로 84%까지 감소하는 것도 확인할 수 있었다. 오염현장에서 최고의 TCE 농도(1.8 μM)를 가지는 현장지하수를 이용하여 처리하였을 때는 TCE 농도가 낮아 25 g/L의 NANOFER 25를 사용하여 10시간 내 90% 이상의 TCE를 분해할 수 있었다. 본 연구결과와 현장 오염지하수에 대한 수리, 지질학적 조사결과를 접목할 경우, 향후 효율적인 현장 지하수처리 결과를 도출할 수 있을 것으로 예상된다. Nanoscale zero-valent iron (NZVI) particles were tested as remediation media for groundwater contaminated by organic pollutants (e.g., TCE, trichloroethylene). The contaminated groundwater contained anions (NO₃ -, Cl-, SO₄^2-, and HCO₃-) and natural organic matter (NOM). Treatability of commercial NZVI particles (NANOFER 25, Nanoiron, Czech) was tested by using a synthetic groundwater and the field groundwater samples. More than 95% of 1.8 mM TCE was removed within 20 hours with a NZVI dosage of 25 g/L (k = 0.15 hr-1). Repetitive degradation experiments revealed that the removal capacity of NANOFER 25 was 0.19 mmole TCE/g NZVI. TCE degradation reactions were not substantially affected by the presence of each anion with concentrations as high as 100 times the average field concentrations. However, when the four anions (NO₃-, Cl-, SO₄2-), HCO₃-) were present simultaneously. the degradation reactivity and removal capacity were decreased by 60% (k = 0.069 hr-1) and 10%, respectively. The k value of TCE degradation in the presence of NZVI (25 g/L) with dissovled organic carbon of 2.5 mg/L was also decreased by 84% (k = 0.025 hr-1). In the experiments with the field groundwater, more than 90% of 1.8 μM TCE, which is the concentration of TCE at the source zone, was removed within 10 hours with a NANOFER 25 dosage of 25 g/L. The results imply that the contaminated groundwater can effectively be treated by NANOFER 25 with more information on the hydrogeology of the site.

보문 : 에너지/환경 ; 이중용매에서 제조된 나노영가철을 이용한 질산성질소의 환원반응성 평가

박희수 ( Hee Su Park ),박용민 ( Yong Min Park ),오수경 ( Soo Kyeong Oh ),이성재 ( Seong Jae Lee ),최용수 ( Yong Su Choi ),이상협 ( Sang Hyup Lee ) 한국화학공학회 2008 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.46 No.5

A cost-effective method to prepare size-controlled nanoscale zero-valent iron for nitrate reduction

Claudio Adrian Ruiz-Torres,Rene Fernando Araujo-Martinez,Gabriel Alejandro Martinez-Cas,J. Elpidio Morales-Sanchez,Tae-Jin Lee,Hyun-Sang Shin,Yuhoon Hwang,Abel Hurtado-Macias,Facundo Ruiz 대한환경공학회 2019 Environmental Engineering Research Vol.24 No.3

Nanoscale zero-valent iron (nZVI) has proved to be an effective tool in applied environmental nanotechnology, where the decreased particle diameter provides a drastic change in the properties and efficiency of nanomaterials used in water purification. However, the agglomeration and colloidal instability represent a problematic and a remarkable reduction in nZVI reactivity. In view of that, this study reports a simple and cost-effective new strategy for ultra-small (< 7.5%) distributed functionalized nZVI-EG (1-9 ㎚), with high colloidal stability and reduction capacity. These were obtained without inert conditions, using a simple, economical synthesis methodology employing two stabilization mechanisms based on the use of non-aqueous solvent (methanol) and ethylene glycol (EG) as a stabilizer. The information from UV-Vis absorption spectroscopy and Fourier transform infrared spectroscopy suggests iron ion coordination by interaction with methanol molecules. Subsequently, after nZVI formation, particle-surface modification occurs by the addition of the EG. Size distribution analysis shows an average diameter of 4.23 ㎚ and the predominance (> 90%) of particles with sizes < 6.10 ㎚. Evaluation of the stability of functionalized nZVI by sedimentation test and a dynamic light-scattering technique, demonstrated very high colloidal stability. The ultra-small particles displayed a rapid and high nitrate removal capacity from water.

Effects of oxidants on <i>in situ</i> treatment of a DNAPL source by nanoscale zero-valent iron: A field study

Ahn, Jun-Young,Kim, Cheolyong,Kim, Hong-Seok,Hwang, Kyung-Yup,Hwang, Inseong Elsevier 2016 Water research Vol.107 No.-

<P><B>Abstract</B></P> <P>This study aimed to evaluate the efficiency of a nanoscale zero-valent iron (NZVI)-based treatment process for an aquifer contaminated with trichloroethylene (TCE) in which TCE in dense non-aqueous phase liquid (DNAPL) form was also present. The study further investigated the effects of site oxidants on the reactivity and lifetime of NZVI. The injection of 30 kg of NZVI into the site successfully removed 95.7% of TCE in the groundwater within the first 60 days without producing chlorinated intermediates. The chloride balance analysis estimated that 2214 g of TCE was removed and confirmed the presence of DNAPL TCE. The oxidation of NZVI particles by nitrate, dissolved oxygen (DO), and TCE consumed 29.5%, 13.5%, and 14.3% of the Fe(0) initially present, respectively, over 60 days. Thus, nitrate was identified as the priority among groundwater oxidants. The reactive lifetime of NZVI at the site was found to be at least 103 days, based on the monitoring of TCE, DO, and nitrate concentrations, oxidation-reduction potential (ORP), and the residual Fe(0) content of the NZVI particles. Solid samples that were retrieved from the site on the 165th day still contained substantial amounts of Fe(0), occupying up to 21.9% of the total mass, and retained considerable reactivities towards TCE. This indicates that the NZVI particles aged more than 5 months at the site can potentially be reused for TCE reduction even after extensive corrosion of Fe(0) has occurred.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A DNAPL-polluted aquifer was successfully remediated <I>in situ</I> with an NZVI. </LI> <LI> Oxidants such as DO and nitrate greatly affected the TCE reduction in the field. </LI> <LI> Nitrate showed the highest reactivity towards NZVI among the oxidants. </LI> <LI> The reactive lifetime of NZVI at the site was found to be at least 103 days. </LI> <LI> NZVI particles aged for 165 days at the site still retained reactivity towards TCE. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

나노 영가철 환원 반응성의 정량 분석을 위한 수정된 인도페놀법 적용

황유훈(Yuhoon Hwang),이원태(Wontae Lee),Henrik R. Andersen 대한환경공학회 2016 대한환경공학회지 Vol.38 No.12

나노 기술에 대한 관심이 증가함에 따라 다양한 종류의 나노 물질이 환경 정화 분야에서 활발히 연구되고 있다. 이에 따라 새롭게 개발된 나노 물질의 성능을 쉽고 신속하게 측정할 수 있는 분석법에 대한 요구가 증가하고 있다. 본 연구에서는 토양/지하수 정화 분야에서 활발히 사용되는 나노 영가철의 환원 반응성을 쉽고 신속하게 측정할 수 있는 방법으로써 수정된 인도페놀법을 제시하였다. 인도페놀법에서 한계반응물로 작용하던 암모늄과 과량으로 존재하던 페놀을 치환하여 사용함으로써 페놀류에 대한 정량 분석이 가능하도록 수정하였다. 대상으로 한 나노 영가철에 의한 환원 반응은 4-클로로페놀의 페놀로의 환원과 나이트로벤젠의 아닐린으로의 환원이었으며, 수정된 인도페놀법은 반응생성물인 페놀과 아닐린에 대하여 선택성을 나타내 분석 방법으로 사용이 가능함을 확인하였다. 민감도 향상을 위하여 발색 시약의 농도 및 반응 시간, 시료의 전처리 등의 영향에 대하여 평가하였다. 실제 시료를 대상으로 시험하였을 때, 용존 철 이온에 의한 저해 영향을 확인하여 탄산나트륨 용액 주입의 전처리를 이용하여 해결하였다. 최종적으로 개발된 분석 방법을 이용하여 나노 영가철 및 이중금속 나노영가철의 환원 반응성을 측정하였으며, 결과적으로 환원 반응 속도의 차이뿐 아니라 환원 기작의 차이도 구분할 수 있는 가능성을 보여 주어 나노 영가철의 환원과 관련된 연구 분야에서 유용하게 사용될 수 있을 것으로 사료된다. Nanoscale zero-valent iron (nZVI) has been effectively applied for environmental remediation due to its ability to reduce various toxic compounds. However, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of nZVIs. A modified indophenol method was suggested to determine reducing activity of nZVI. The method was originally developed to determine aqueous ammonia concentration, but it was further modified to quantify phenol and aniline. The assay focused on analysis of reduction products rather than its mother compounds, which gave more accurate quantification of reductive activity. The suggested color assay showed superior selectivity toward reduction products, phenol or aniline, in the presence of mother compounds, 4-chlorophenol or nitrobenzene. Reaction conditions, such as reagent concentration and reaction time, were optimized to maximize sensitivity. Additionally, pretreatment step using Na₂CO₃ was suggested to eliminate the interference of residual iron ions. Monometallic nZVI and bimetallic Ni/Fe were investigated with the reaction. The substrates showed graduated reactivity, and thus, reduction potency and kinetics of different materials and reaction mechanism was distinguished. The colorimetric assay based on modified indophenol reaction can be promises to be a useful and simple tool in various nZVI related research topics.

TCE 오염 지하수의 정화를 위한 나노영가철 기반 반응존 공법의 현장 적용성 연구

안준영,김철용,황경엽,전성천,황인성,Ahn, Jun-Young,Kim, Cheolyong,Hwang, Kyung-Yup,Jun, Seong-Chun,Hwang, Inseong 한국지하수토양환경학회 2014 지하수토양환경 Vol.19 No.6

The laboratory and field studies were conducted to identify an optimal injection concentration of nanoscale zero-valent iron particles (NZVI) and to evaluate the applicability of NZVI-based reactive zone technology to the site contaminated with trichloroethylene (TCE) DNAPL (Dense Non-Aqueous Phase Liquid). The laboratory test found an optimal injection concentration of NZVI of 5 g/L that could remove more than 95% of 0.15 mM TCE within 20 days. Eleven test wells were installed at the aquifer that was mainly composed of alluvial and weathered soils at a strong oxic condition with dissolved oxygen concentration of 3.50 mg/L and oxidation-reduction potential of 301 mV. NZVI of total 30 kg were successfully injected using a centrifugal pump. After 60 days from the NZVI injection, 86.2% of the TCE initially present in the groundwater was removed and the mass of TCE removed was 405 g. Nonchlorinated products such as ethane and ethene were detected in the groundwater samples. Based on the increased chloride ion concentration at the site, the mass of TCE removed was estimated to be 1.52 kg. This implied the presence of DNAPL TCE which contributed to a higher estimate of TCE removal than that based on the TCE concentration change.

Hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX)의 환원적 분해를 위한나노영가철의 성능평가: 회분식 및 칼럼 실험

이충섭,오다솜,조성희,이진욱,장윤석,Lee, Chung-Seop,Oh, Da-Som,Cho, Sung-Heui,Lee, Jin-Wook,Chang, Yoon-Seok 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.6

Reductive degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by nanoscale zero-valent iron (nZVI) was investigated to evaluate the feasibility of using it for in-situ groundwater remediation. Batch experiments were conducted to quantify the kinetics and efficiency of RDX removal by nZVI, and to determine the effects of pH, dissolved oxygen (DO), and ionic strength on this process. Experimental results showed that the reduction of RDX by nZVI followed pseudo-first order kinetics with the observed rate constant (k_obs) in the range of 0.0056-0.0192 min⁻¹. Column tests were conducted to quantify the removal of RDX by nZVI under real groundwater conditions and evaluate the potential efficacy of nZVI for this purpose in real conditions. In column experiment, RDX removal capacity of nZVI was determined to be 82,500 mg/kg nZVI. pH, oxidation-reduction potential (ORP), and DO concentration varied significantly during the column experiments; the occurrence of these changes suggests that monitoring these quantities may be useful in evaluation of the reactivity of nZVI, because the most critical mechanisms for RDX removal are based on the chemical reduction reactions. These results revealed that nZVI can significantly degrade RDX and that use of nZVI could be an effective method for in-situ remediation of RDX-contaminated groundwater.