Effects of chemical contamination on microscale structural characteristics of intact loess and resultant macroscale mechanical properties

Hu, Wenle; Cheng, Wen-Chieh; Wen, Shaojie; Rahman, M.F.

doi:10.1016/j.catena.2021.105361

Cited by 100 publications

(27 citation statements)

References 49 publications

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“…However, they are usually time-consuming and may cause secondary pollution (Achal et al, 2012;Nancharaiah et al, 2016;Kappaun et al, 2018;Xue et al, 2022;Yan et al, 2021;Duan et al, 2021a;Cheng et al, 2021;Duan et al, 2021b). Furthermore, heavy metal ions may be re-released into surrounding environments when subjected to the change in environmental conditions (Hu et al, 2021b;Bai et al, 2017;Bai et al, 2021;Xue et al, 2021). In light of this, a sustainable countermeasure that is able to immobilize heavy metal ions using an environmental-friendly manner is considered of great necessity.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Calcium Source on Pb and Cu Remediation Using Enzyme-Induced Carbonate Precipitation

Wang

Cheng

Xue

2022

Front. Bioeng. Biotechnol.

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Heavy metal contamination not only causes threat to human health but also raises sustainable development concerns. The use of traditional methods to remediate heavy metal contamination is however time-consuming, and the remediation efficiency may not meet the requirements as expected. The present study conducted a series of test tube experiments to investigate the effect of calcium source on the lead and copper removals. In addition to the test tube experiments, numerical simulations were performed using Visual MINTEQ software package considering different degrees of urea hydrolysis derived from the experiments. The remediation efficiency degrades when NH4+ and OH− concentrations are not sufficient to precipitate the majority of Pb2+ and Cu2+. It also degrades when CaO turns pH into highly alkaline conditions. The numerical simulations do not take the dissolution of precipitation into account and therefore overestimate the remediation efficiency when subjected to lower Pb(NO3)2 or Cu(NO3)2 concentrations. The findings highlight the potential of applying the enzyme-induced carbonate precipitation to lead and copper remediations.

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Section: Introductionmentioning

confidence: 99%

The Effect of Calcium Source on Pb and Cu Remediation Using Enzyme-Induced Carbonate Precipitation

Wang

Cheng

Xue

2022

Front. Bioeng. Biotechnol.

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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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“…The fundamental principle of applying the bioinspired calcium carbonate precipitation technology to the immobilization of heavy metals is to catalyze urea hydrolysis using the ureolytic bacteria toward discharging hydroxide ions and ammonium ions and precipitating calcium carbonate with heavy metals ( Schwantes-Cezario et al, 2017 ; Qiao et al, 2019 ; Schwantes-Cezario et al, 2020 ; Yang et al, 2020 ; Hu et al, 2021a ; Hu et al, 2021b ; Yuyang Zhang et al, 2021 ; Yuan et al, 2021 ). The whole process is also referred to as “biomineralization”, and heavy metal migration potential can be substantially reduced when capsulized using the calcium carbonate precipitation, minimizing their threats to surrounding environments ( Zhu and Maria, 2016 ; Arias et al, 2019 ; Teng et al, 2019 ; Song et al, 2021 ) (see Eqs 1 – 7 ).…”

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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Effects of chemical contamination on microscale structural characteristics of intact loess and resultant macroscale mechanical properties

Cited by 100 publications

References 49 publications

The Effect of Calcium Source on Pb and Cu Remediation Using Enzyme-Induced Carbonate Precipitation

The Effect of Calcium Source on Pb and Cu Remediation Using Enzyme-Induced Carbonate Precipitation

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

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