Investigating microscale structural characteristics and resultant macroscale mechanical properties of loess exposed to alkaline and saline environments

Wang, Lin; Cheng, Wen-Chieh; Xue, Zhong-Fei

doi:10.1007/s10064-022-02640-z

Cited by 43 publications

(14 citation statements)

References 51 publications

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“…Heavy metal contamination in the soil and underground water seriously threatens surrounding fragile environments and human health ( Kim et al, 2001 ; Mohan et al, 2006 ; Bai et al, 2017 ; Chang et al, 2019 ; Chen et al, 2022a ; Hu et al, 2020 ; Bai et al, 2021 ; Hu et al, 2021 ; Liu et al, 2021 ; Xue et al, 2021 ; Hu et al, 2022 ; Wang et al, 2022 ). Such heavy metal contamination remediation by the traditional soil flushing measure is deemed time-consuming and costly since heavy metal ions are easily adsorbed by soil particles, and intensive industrial activities further aggravate heavy metal contamination ( Yang et al, 2014 ; An et al, 2019 ; Kumar and Dwivedi, 2019 ; Bai et al, 2021 ; Cheng et al, 2021 ; Duan et al, 2021 ; Wei et al, 2021 ; Yuan et al, 2021 ; Chen et al, 2022b ).…”

Section: Introductionmentioning

confidence: 99%

Effects of the Urease Concentration and Calcium Source on Enzyme-Induced Carbonate Precipitation for Lead Remediation

et al. 2022

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Heavy metal contamination during the rapid urbanization process in recent decades has notably impacted our fragile environments and threatens human health. However, traditional remediation approaches are considered time-consuming and costly, and the effect sometimes does not meet the requirements expected. The present study conducted test tube experiments to reproduce enzyme-induced carbonate precipitation applied to lead remediation under the effects of urease concentration and a calcium source. Furthermore, the speciation and sequence of the carbonate precipitation were simulated using the Visual MINTEQ software package. The results indicated that higher urease concentrations can assure the availability of CO32− during the enzyme-induced carbonate precipitation (EICP) process toward benefiting carbonate precipitation. The calcium source determines the speciation of carbonate precipitation and subsequently the Pb remediation efficiency. The use of CaO results in the dissolution of Pb(OH)2 and, therefore, discharges Pb ions, causing some difficulty in forming the multi-layer structure of carbonate precipitation and degrading Pb remediation. The findings of this study are useful in widening the horizon of applications of the enzyme-induced carbonate precipitation technology to heavy metal remediation.

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Section: Introductionmentioning

confidence: 99%

Effects of the Urease Concentration and Calcium Source on Enzyme-Induced Carbonate Precipitation for Lead Remediation

et al. 2022

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“…The mobility or solubility of heavy metals can transform them from the solid phase to the solution phase, thereby increasing their bioavailability ( Bolan et al, 2014 ; Bai et al, 2020 , Bai et al, 2021c ; Yang et al, 2021 ; Xue et al, 2022 ). Therefore, immobilizing heavy metals is considered to be of great necessity in order to reduce their bioavailability ( Li et al, 2013 ; Khadim et al, 2019 ; Cheng et al, 2021 ; Hu et al, 2021 ; Hu et al, 2022 ; Wang et al, 2022; Wang et al, 2022 ; Wang et al, 2022 ). To this end, chemical precipitation, electroremediation, and ion-exchange and adsorption have been widely adopted as countermeasures.…”

Section: Introductionmentioning

confidence: 99%

Effects of Bacterial Culture and Calcium Source Addition on Lead and Copper Remediation Using Bioinspired Calcium Carbonate Precipitation

Xue

Cheng

Wang

et al. 2022

Front. Bioeng. Biotechnol.

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Lead and copper ions from wastewater induced by metallurgical processes are accumulated in soils, threatening plant and human health. The bioinspired calcium carbonate precipitation is proven effective in improving the cementation between soil particles. However, studies on capsulizing heavy metal ions using the bioinspired calcium carbonate precipitation are remarkably limited. The present study conducted a series of test tube experiments to investigate the effects of bacterial culture and calcium source addition on the remediation efficiency against lead and copper ions. The calcium carbonate precipitation was reproduced using the Visual MINTEQ software package to reveal the mechanism affecting the remediation efficiency. The degradation in the remediation efficiency against lead ions relies mainly upon the degree of urea hydrolysis. However, higher degrees of urea hydrolysis cause remediation efficiency against copper ions to reduce to zero. Such high degree of urea hydrolysis turns pH surrounding conditions into highly alkaline environments. Therefore, pursuing higher degrees of urea hydrolysis might not be the most crucial factor while remedying copper ions. The findings shed light on the importance of modifying pH surrounding conditions in capsulizing copper ions using the bioinspired calcium carbonate precipitation.

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“…The currently available measures for the remediation of soil contaminated by heavy metals mainly include phytoremediation (Caparrós et al, 2022;He et al, 2022;Liu et al, 2022;Wu et al, 2022), thermal desorption (Ding et al, 2019;Liu et al, 2019Liu et al, , 2020, biosorption (Saha et al, 2011;Mukherjee et al, 2013), soil replacement (Du et al, 2011, curing stabilization (Kalantari and Prasad, 2014;Zhou et al, 2017;Wang et al, 2019), chemical precipitation (Lu Y. S. et al, 2019;Muddanna and Baral, 2019), and microbial remediation (Garcia-Sanchez et al, 2018;Lu C. et al, 2019;Wang et al, 2022a;Xue et al, 2022). Among the remediation measures, electrokinetic (EK) remediation has recently come under the spotlight and is considered a promising innovative remediation technology, especially for low permeability soils.…”

Section: Introductionmentioning

confidence: 99%

“…Clay minerals in loess have complex chemical composition, high specific surface areas, and high negative charge (Xue et al, 2021a(Xue et al, , 2021bDuan et al, 2021;Bai B. et al, 2021Bai B. et al, , 2021b. The forming of water during the EK remediation process can cause the swelling and dispersion of clays in loess toward increasing the thickness of the electric double layer and causing a reduction in the suction (Hu et al, 2021a;Hu et al, 2022a;Wang et al, 2022a). The reduced suction deteriorates the metastable structure of the loess, accompanied by the collapse deformation (Wang et al, 2020;Hu et al, 2021a), which makes the channel of the pore decrease and further limits the application of EK remediation technology.…”

Section: Introductionmentioning

confidence: 99%

Revealing underlying mechanisms affecting electrokinetic remediation of an artificially Cu- and Pb-contaminated loess using the external regulatory system with adsorbent

Cheng

Wen

et al. 2022

Front. Mater.

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Considering extensive metallurgical mining activities in the northwest of China, handling Cu- and Pb-rich wastewater is a challenging task. Inappropriate handling of the Cu- and Pb-rich wastewater can lead to accumulation of Cu and Pb in the surrounding environment, thereby posing a serious threat to human health. Electrokinetic (EK) technology is an increasingly popular alternative to traditional approaches for contaminated soil remediation owing to its high effectiveness and low risk of secondary pollution. This study first proposed an external regulatory system with the adsorbent (ERSA) and investigated the effect of electrode type, ERSA, and cation exchange membrane (CEM) on the EK remediation of an artificially Cu- and Pb-contaminated loess. An EK reactor incorporating ERSA was applied to the EK experiments to circulate the electrolyte, not only making pH surrounding the cathode lower, but also preventing the formation of precipitation. The electrokinetic geosynthetics electrode released H+ and OH− faster and promoted their migration toward the specimen. However, because of the faster precipitation near the cathode, the boost in the remediation efficiency was hindered. Furthermore, considering the ERSA use, a decrease in soil pH near the cathode reduced the precipitation, thereby enhancing the EK remediation efficiency. In contrast, the use of CEM lowered the soil pH, increased the soil electrical conductivity (EC) and electric current, and aggravated the electroosmotic flow. The Cu remediation efficiency using the modified EK reactor was largely lifted to 85.52%, while the Pb remediation efficiency increased to 75.51%. These results shed light on an enhancement on the EK remediation efficiency and the potential of applying the modified EK reactor to remedy Cu- and Pb-rich water bodies.

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Investigating microscale structural characteristics and resultant macroscale mechanical properties of loess exposed to alkaline and saline environments

Cited by 43 publications

References 51 publications

Effects of the Urease Concentration and Calcium Source on Enzyme-Induced Carbonate Precipitation for Lead Remediation

Effects of the Urease Concentration and Calcium Source on Enzyme-Induced Carbonate Precipitation for Lead Remediation

Effects of Bacterial Culture and Calcium Source Addition on Lead and Copper Remediation Using Bioinspired Calcium Carbonate Precipitation

Revealing underlying mechanisms affecting electrokinetic remediation of an artificially Cu- and Pb-contaminated loess using the external regulatory system with adsorbent

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