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J Hazard Mater ; 423(Pt A): 127104, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34523482


Soils contamination with Cd result in detriment to the environmental quality. In-situ immobilization methods by applying clay minerals have been gaining prominence. The effects on sepiolite of thermal activation at different temperatures (300-750 °C), for removing Cd from aqueous solutions were evaluated, in order to consider their further application for soil remediation. The influence of activation temperature was investigated using XRD, SEM, and N2 adsorption-desorption measurements. The S-600 exhibited the maximum adsorption capacity (21.28 mg/g), despite its lower SSA, and Langmuir model described the adsorption isotherms better than the Freundlich equation. TCLP was used to quantify the remediation effects of thermal-activated sepiolite on simulated soils artificially polluted with Cd. The results indicated that the mobility of Cd in soil was effectively reduced after treating with thermal-activated sepiolite and the use of S-600 was the most efficient, reducing the TCLP-Cd by approximately 73% compared with the control test. The main remediation mechanism was considered as the cation exchange of Cd by Mg at the edges of octahedral sheet. This study showed that thermal-activated sepiolite could be promising amendments for remediation of Cd-contaminated soil.

J Mater Chem B ; 9(2): 404-409, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33283827


Montmorillonite (MMT), as a naturally sourced and FDA-approved biomaterial, has attracted considerable attention due to its extensive application in biomedical areas, such as intestinal ailments, drug delivery, and additive manufacturing. In this work, two-dimensional montmorillonite (2D-MMT) ultrathin nanosheets were successfully prepared from sodium montmorillonite (Na-MMT) by utilizing a freeze-drying assisted method. Possessing a large specific surface area and increased number of exposed hydroxyl groups, 2D-MMT nanosheets exhibited better antibacterial ability than the original Na-MMT. More strikingly, we found that both 2D-MMT nanosheets and Na-MMT could generate reactive oxygen species (ROS) upon visible light illumination, which could promote their antibacterial efficiency. As a result, 2D-MMT nanosheets showed efficient antibacterial performance in the presence of light towards Escherichia coli with a simultaneous enhancement of surface adsorption and photodynamic ablation. What's more, a possible mechanism for ROS generation by MMT upon light illumination was first proposed in this work. The combination of the increased physical adsorption capacity and ROS generation ability of 2D-MMT nanosheets would help inspire the development of MMT as a promising antimicrobial candidate in the future.

Antibacterianos/metabolismo , Bentonita/química , Nanotecnologia/métodos , Fotoquimioterapia/métodos , Humanos , Espécies Reativas de Oxigênio
Sci Total Environ ; 697: 134073, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31473547


The improvement of urban river revetment soil is conducive to promote the growth of pioneer plants which can accelerate the restoration of ecosystems. How to effectively amend soil structure and composition to provide a suitable soil rhizosphere for rapid plant expansion is essential to be solved in the study. Biochar and lake dredged sediments were used to amend an urban river bank soil, where compaction and lack of mineral nutrition hindered the growth of Phragmites. The study found that the addition of 50% mass of dredged sediments combined with 5% mass of straw biochar increased the plant height maximum growth rate, tiller number per unit area, and root biomass by 32.93%, 29.62%, and 41.39%, respectively. The reason for these positive effects on plant growth mainly involved the improvement of rhizosphere soil properties. Addition of biochar increased porosity and available phosphorus content while dredged sediments increased soil organic carbon, thereby increasing the underground unit total phosphorus content of Phragmites by 18.18%. An increase of the Alpha diversity index of rhizosphere microorganisms (8.18%) and the decrease in infection rate of arbuscular mycorrhizal fungi (23.61%) also proved that the rapid expansion of Phragmites was improved owing to changes of the soil physicochemical properties. The combination of biochar and dredged sediments realized synergistic improvement of soil physical structure and increase of nutrient content, which helped promote the growth and expansion of the underground part of Phragmites. This cost-effective method can be feasible used for improvement of urban river revetment ecosystem.

Recuperação e Remediação Ambiental/métodos , Poaceae/crescimento & desenvolvimento , Rizosfera , Microbiologia do Solo , Carvão Vegetal/química , Micorrizas , Fotossíntese