Influence of nanoscale zero-valent iron on hydraulic conductivity of a residual clayey soil and modeling of the filtration parameter

2020 ◽  
Vol 27 (9) ◽  
pp. 9288-9296 ◽  
Author(s):  
Cleomar Reginatto ◽  
Iziquiel Cecchin ◽  
Karla Salvagni Heineck ◽  
Antonio Thomé ◽  
Krishna R. Reddy
Keyword(s):  
Hydraulic Conductivity ◽  
Clayey Soil ◽  
Zero Valent Iron ◽  
Filtration Parameter ◽  
Nanoscale Zero Valent Iron

scholarly journals A porous biochar supported nanoscale zero-valent iron highly efficient for the remediation of cadmium and lead contaminated soil

2021 ◽  
Author(s):  
Wei Qian ◽  
Zeng-Hui Diao
Keyword(s):  
Heavy Metals ◽  
Clayey Soil ◽  
Zero Valent Iron ◽  
Nanoscale Zero Valent Iron ◽  
Cadmium And Lead ◽  
Concentration Levels ◽  
Pb Immobilization ◽  
Better Than ◽  
Cd Species ◽  
Simultaneous Immobilization

Abstract Risk associated with heavy metals in soil has been received widespread attention. In this study, a porous biochar supported nanoscale zero-valent iron (BC-nZVI) was applied to immobilize cadmium (Cd) and/or lead (Pb) in clayey soil. Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process, and about 80 % of heavy metals immobilization was obtained in BC-nZVI process. Addition of BC-nZVI could increase soil pH and organic matter (SOM). Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol (2,4-DCP), but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels. Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process, and both Cd and Pb availability significantly decreased. Stable Cd species inculding Cd(OH)2, CdCO3 and CdO were formed, whereas stable Pb species such as PbCO3, PbO and Pb(OH)2 were produced with BC-nZVI treatment. Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed. This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple metals in soil.

scholarly journals Experimental study of the effect of nanoscale zero-valent iron injected on the permeability of saturated porous media

2021 ◽  
Author(s):  
Jie Tang ◽  
Fei Liu ◽  
Chong Zhang ◽  
Qiang Xue
Keyword(s):  
Porous Media ◽  
Hydraulic Conductivity ◽  
Zero Valent Iron ◽  
Source Zone ◽  
Distribution Area ◽  
Saturated Porous Media ◽  
Loss Mechanism ◽  
Injection Point ◽  
Nanoscale Zero Valent Iron ◽  
Constant Head

Abstract In comparison of modified nanoscale zero-valent iron (NZVI), bare NZVI used to remediate deep contaminated groundwater source areas has more advantages. However, the influences of injected bare NZVI deposition on the permeability of aquifer remain unclear, which are still the key factors of engineering cost and contamination removal. Hence, this study sought to assess method of measuring hydraulic conductivity with constant head device and examine the permeability loss mechanism of NZVI injected into different saturated porous media, using column tests. The results showed that it was feasible to determine hydraulic conductivity by the constant head device. The permeability loss caused by NZVI injection increased with a decrease in grain size of porous media, and was determined by the amount and distribution of NZVI deposition. NZVI distribution area had a good linear correlation with dispersivity of the porous media. Additionally, although surface clogging occurred in all porous media, the amount of NZVI deposition at the injection point in fine sand was largest, so that its permeability loss was the most, which was more likely to cause hydraulic fracturing and then expand the area of contaminant source zone. These results have implications for NZVI field injection to successful groundwater remediation.

scholarly journals Use of Nanoscale Zero-Valent Iron for Remediation of Clayey Soil Contaminated with Hexavalent Chromium: Batch and Column Tests

2020 ◽  
Vol 17 (3) ◽  
pp. 1001 ◽  
Author(s):  
Cleomar Reginatto ◽  
Iziquiel Cecchin ◽  
Karla Salvagni Heineck ◽  
Antonio Thomé ◽  
Krishna R. Reddy
Keyword(s):  
Hexavalent Chromium ◽  
Clayey Soil ◽  
Gradual Increase ◽  
Zero Valent Iron ◽  
Residual Soil ◽  
Column Tests ◽  
Injection Process ◽  
Batch Tests ◽  
Nanoscale Zero Valent Iron

This study investigated the reduction of hexavalent chromium (Cr(VI)) in a clayey residual soil using nanoscale zero-valent iron (nZVI). Five different ratios between nZVI and Cr(VI) were tested in batch tests (1000/11; 1000/23; 1000/35; 1000/70, and 1000/140 mg/mg) with the soil. With the selected proportion resulting best efficiency, the column tests were conducted, with molded specimens of 5 cm in diameter and 5 cm in height, with different nZVI injection pressures (10, 30, and 100 kPa). The soil was contaminated with 800 mg/kg of Cr(VI). The Cr(VI) and Cr(III) analyses were performed following the USEPA 3060A and USEPA 7196A standards. The results show that the reduction of Cr(VI) is dependent on the ratio between nZVI and Cr(VI), reaching 98% of efficiency. In column tests, the pressure of 30 kPa was the most efficient. As pressure increased, contaminant leaching increased. The permeability decreased over time due to the gradual increase in filtration and formation of oxyhydroxides, limiting nZVI mobility. Overall, nZVI is efficient for soil remediation with Cr(VI), but the injection process can spread the contaminated if not properly controlled during in situ application.

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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