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    An overview of preparation and applications of stabilized zero-valent iron nanoparticles for soil and groundwater remediation. Zhao Xiao,Liu Wen,Cai Zhengqing,Han Bing,Qian Tianwei,Zhao Dongye Water research Nano-scale zero-valent iron (nZVI) is one of the most intensively studied materials for environmental cleanup uses over the past 20 years or so. Freshly prepared nZVI is highly reactive due to its high specific surface area and strong reducing power. Over years, the classic borohydride reduction method for preparing nZVI has been modified by use of various stabilizers or surface modifiers to acquire more stable and soil deliverable nZVI for treatment of different organic and inorganic contaminants in water and soil. While most studies have been focused on testing nZVI for water treatment, the greater potential or advantage of nZVI appears to be for in situ remediation of contaminated soil and groundwater by directly delivering stabilized nZVI into the contaminated subsurface as it was proposed from the beginning. Compared to conventional remediation practices, the in situ remediation technique using stabilized nZVI offers some unique advantages. This work provides an update on the latest development of stabilized nZVI for various environmental cleanup uses, and overviews the evolution and environmental applications of stabilized nZVI. Commonly used stabilizers are compared and the stabilizing mechanisms are discussed. The effectiveness and constraints of the nZVI-based in situ remediation technology are summarized. This review also reveals some critical knowledge gaps and research needs, such as interactions between delivered nZVI and the local biogeochemical conditions. 10.1016/j.watres.2016.05.019
    Groundwater Chemistry Has a Greater Influence on the Mobility of Nanoparticles Used for Remediation than the Chemical Heterogeneity of Aquifer Media. Micić Vesna,Bossa Nathan,Schmid Doris,Wiesner Mark R,Hofmann Thilo Environmental science & technology The application of nanoscale zerovalent iron (nano-ZVI) particles for groundwater remediation has spurred research into the influence of the collector heterogeneity on the nano-ZVI mobility. The chemical heterogeneity of surfaces within aquifer media affects their surface charge distribution and their affinity for nano-ZVI. The groundwater chemistry affects the properties of both aquifer surfaces and the nano-ZVI particles. Commercial poly(acrylic acid)-coated nano-ZVI (PAA-nano-ZVI) particles were tested in column experiments using two solution chemistries and silica collectors with different degrees of chemical heterogeneity, achieved by ferrihydrite coating. A porous media filtration model was used to determine the attachment efficiency of PAA-nano-ZVI particles, and the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to describe the interactions between PAA-nano-ZVI particles and the aquifer "collectors". The mobility of PAA-nano-ZVI particles suspended in ultrapure water depended on the extent of ferrihydrite coating on the collector surfaces. The mobility of PAA-nano-ZVI particles under environmentally relevant conditions was independent of the collector chemical heterogeneity. The size of PAA-nano-ZVI aggregates doubled, inducing gravitational sedimentation and possibly straining as mechanisms of particle deposition. There was no repulsive energy barrier between particles and collectors, and the DLVO theory was unable to explain the observed particle attachment. Our results suggest that the groundwater chemistry has a greater influence on the mobility of PAA-nano-ZVI particles than the collector chemical heterogeneity. A better understanding of polymer adsorption to nanoparticles and its conformation under natural groundwater conditions is needed to further elucidate nanoparticle-collector interactions. 10.1021/acs.est.9b06135
    Zero-Valent Iron Nanoparticles for Soil and Groundwater Remediation. Galdames Alazne,Ruiz-Rubio Leire,Orueta Maider,Sánchez-Arzalluz Miguel,Vilas-Vilela José Luis International journal of environmental research and public health Zero-valent iron has been reported as a successful remediation agent for environmental issues, being extensively used in soil and groundwater remediation. The use of zero-valent nanoparticles have been arisen as a highly effective method due to the high specific surface area of zero-valent nanoparticles. Then, the development of nanosized materials in general, and the improvement of the properties of the nano-iron in particular, has facilitated their application in remediation technologies. As the result, highly efficient and versatile nanomaterials have been obtained. Among the possible nanoparticle systems, the reactivity and availability of zero-valent iron nanoparticles (NZVI) have achieved very interesting and promising results make them particularly attractive for the remediation of subsurface contaminants. In fact, a large number of laboratory and pilot studies have reported the high effectiveness of these NZVI-based technologies for the remediation of groundwater and contaminated soils. Although the results are often based on a limited contaminant target, there is a large gap between the amount of contaminants tested with NZVI at the laboratory level and those remediated at the pilot and field level. In this review, the main zero-valent iron nanoparticles and their remediation capacity are summarized, in addition to the pilot and land scale studies reported until date for each kind of nanomaterials. 10.3390/ijerph17165817
    Application of magnesium peroxide (MgO) nanoparticles for toluene remediation from groundwater: batch and column studies. Mosmeri Hamid,Gholami Fatemeh,Shavandi Mahmoud,Alaie Ebrahim,Dastgheib Seyed Mohammad Mehdi Environmental science and pollution research international In the present study, magnesium peroxide (MgO) nanoparticles were synthesized by electro-deposition process and characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The batch experiments were conducted to evaluate the MgO half-life (600 mg/L) in groundwater under various temperatures (4, 15, and 30 °C) and initial pH (3, 7, and 12). The effect of Fe ions (enhanced oxidation) on the toluene remediation by MgO was also investigated. Nanoparticles were injected to sand-packed continuous-flow columns, and toluene removal (50 ppm) was studied within 50 days at 15 °C. The results indicated that the half-life of MgO at pH 3 and 12 were 5 and 15 days, respectively, in comparison to 10 days at the initial pH 7 and 15 °C. The nanoparticles showed 20 and 7.5 days half-life at 4 and 30 °C temperatures, respectively. Injection of Fe ions indicated an impressive effect on toluene removal by MgO, and the contaminant was completely removed after 5 and 10 days, in the batch and column experiments, respectively. Confocal laser scanning microscope (CLSM) analysis indicated that the attached biofilm had a significant role in the decontamination of groundwater. Comparison of bioremediation and enhanced oxidation resulted in a considerable insight into the application of magnesium peroxide in groundwater remediation. Graphical abstract ᅟ. 10.1007/s11356-018-2920-3
    In-situ remediation of hexavalent chromium contaminated groundwater and saturated soil using stabilized iron sulfide nanoparticles. Wang Tao,Liu Yuanyuan,Wang Jiajia,Wang Xizhi,Liu Bin,Wang Yingxu Journal of environmental management Hexavalent chromium (Cr(VI)) is one of prevalent toxic and mobile heavy metal contaminants in the environment. In this study, synthetic iron sulfide nanoparticles (FeS NPs) stabilized with carboxymethyl cellulose (CMC) were applied to remediate Cr(VI) contaminated groundwater and saturated soil. The batch test results showed that aqueous Cr(VI) was removed with a capacity as high as 1046.1 mg Cr(VI) per gram of FeS NPs. The removal of aqueous Cr(VI) mainly involves adsorption, reduction and co-precipitation. Aqueous Cr(VI) removal by using FeS NPs was a strong pH-dependent process. Dissolved oxygen (DO) would compete with Cr(VI) for Fe(II) and S(-II) and inhibit the process of Cr(VI) reduction at pH 5.6. For ionic strength and natural organic matter (NOM), there were no significant influences on the aqueous Cr(VI) removal. Column tests demonstrated that the concentrations of Cr(VI) in the effluent were lower than 0.005 mg L after an elution of 45 pore volumes (PVs) of stabilized FeS NPs suspension. The leached Cr(VI) decreased from 4.58 mg L of raw Cr(VI)-contaminated soil to 46.8-80.7 μg L from the surface to bottom treated soil in column through Toxicity Characteristic Leaching Procedure (TCLP). Therefore, the synthesized FeS NPs hold high potential for the in-situ remediation of Cr(VI)-contaminated groundwater and saturated soil. 10.1016/j.jenvman.2018.10.085
    Remediation of heavy metals polluted environment using Fe-based nanoparticles: Mechanisms, influencing factors, and environmental implications. Latif Abdul,Sheng Di,Sun Kai,Si Youbin,Azeem Muhammad,Abbas Aown,Bilal Muhammad Environmental pollution (Barking, Essex : 1987) Environmental pollution by heavy metals (HMs) has raised considerable attention due to their toxic impacts on plants, animals and human beings. Thus, the environmental cleanup of these toxic (HMs) is extremely urgent both from the environmental and biological point of view. To remediate HMs-polluted environment, several nanoparticles (NPs) such as metals and its oxides, carbon materials, zeolites, and bimetallic NPs have been documented. Among these, Fe-based NPs have emerged as an effective choice for remediating environmental contamination, due to infinite size, high reactivity, and adsorption properties. This review summarizes the utilization of various Fe-based NPs such as nano zero-valent iron (NZVI), modified-NZVI, supported-NZVI, doped-NZVI, and Fe oxides and hydroxides in remediating the HMs-polluted environment. It presents a comprehensive elaboration on the possible reaction mechanisms between the Fe-based NPs and heavy metals, including adsorption, oxidation/reduction, and precipitation. Subsequently, the environmental factors (e.g., pH, organic matter, and redox) affecting the reactivity of the Fe-based NPs with heavy metals are also highlighted in the current study. Research shows that Fe-based NPs can be toxic to living organisms. In this context, this review points out the environmental hazards associated with the application of Fe-based NPs and proposes future recommendations for the utilization of these NPs. 10.1016/j.envpol.2020.114728
    Naphthalene remediation form groundwater by calcium peroxide (CaO) nanoparticles in permeable reactive barrier (PRB). Gholami Fatemeh,Shavandi Mahmoud,Dastgheib Seyed Mohammad Mehdi,Amoozegar Mohammad Ali Chemosphere This study investigated the applicability of synthesized calcium peroxide (CaO) nanoparticles for naphthalene bioremediation by permeable reactive barrier (PRB) from groundwater. According to the batch experiments the application of 400 mg/L of CaO nanoparticles was the optimum concentration for naphthalene (20 mg/L) bioremediation. Furthermore, the effect of environmental conditions on the stability of nanoparticles showed the tremendous impacts of the initial pH and temperature on the stability and oxygen releasing potential of CaO. Therefore, raising the initial pH from 3 to 12 elevated the dissolved oxygen from 4 to 13.6 mg/L and the stability of nanoparticles was significantly improved around 70 d. Moreover, by increasing the temperature from 4 to 30 °C, the stability of CaO declined from 120 to 30 d. The continuous-flow experiments revealed that the naphthalene-contaminated groundwater was completely bio-remediated in the presence of CaO nanoparticles and microorganisms from the effluent of the column within 50 d. While, the natural remediation of the contaminant resulted in 19.7% removal at the end of the experiments (350 d). Additionally, the attached biofilm on the surface of the PRB zone was studied by scanning electron microscopy (SEM) which showed the higher biofilm formation on the pumice surfaces in the bioremediation column in comparison to the natural remediation column. The physic-chemical characteristics of the effluents from each column was also analyzed and indicated no negative impact of the bioremediation process on the groundwater. Consequently, the present paper provides a comprehensive study on the application of the CaO nanoparticles in PAH-contaminated groundwater treatment. 10.1016/j.chemosphere.2018.08.056
    Benzene-contaminated groundwater remediation using calcium peroxide nanoparticles: synthesis and process optimization. Mosmeri Hamid,Alaie Ebrahim,Shavandi Mahmoud,Dastgheib Seyed Mohammad Mehdi,Tasharrofi Saeideh Environmental monitoring and assessment Nano-size calcium peroxide (nCaO) is an appropriate oxygen source which can meet the needs of in situ chemical oxidation (ISCO) for contaminant remediation from groundwater. In the present study, an easy to handle procedure for synthesis of CaO nanoparticles has been investigated. Modeling and optimization of synthesis process was performed by application of response surface methodology (RSM) and central composite rotatable design (CCRD) method. Synthesized nanoparticles were characterized by XRD and FESEM techniques. The optimal synthesis conditions were found to be 5:1, 570 rpm and 10 °C for HO:CaSO ratio, mixing rate and reaction temperature, respectively. Predicted values showed to be in good agreement with experimental results (R values were 0.915 and 0.965 for CaO weight and nanoparticle size, respectively). To study the efficiency of synthesized nanoparticles for benzene removal from groundwater, batch experiments were applied in biotic and abiotic (chemical removal) conditions by 100, 200, 400, and 800 mg/L of nanoparticles within 70 days. Results indicated that application of 400 mg/L of CaO in biotic condition was able to remediate benzene completely from groundwater after 60 days. Furthermore, comparison of biotic and abiotic experiments showed a great potential of microbial stimulation using CaO nanoparticles in benzene remediation from groundwater. 10.1007/s10661-017-6157-2