Batch treatability studies for a Cr(VI)-contaminated glacial soil from a Cr plating facility were conducted using 1X and 2X the stoichiometric ratio of calcium polysulfide (CPS). The pH of the treated soil increased from 6 to 11 upon CPS addition, but progressively returned to 8-8.5 over the course of 1 year. The 1X dosage maintained a highly reducing environment up to 21 days of monitoring with the samples exposed to atmospheric oxygen, while 2X was reducing up to 180 days of curing. The EPA regulatory method for solid Cr(VI) could not reliably predict Cr(VI) in the treated solid due to ongoing reduction during the test. SPLP results showed that the CPS created an apparent Cr(VI) mobilization during the first 60 days of treatment, with subsequent decrease in soluble Cr(VI) up to 1 year of monitoring. Synchrotron micro-X-ray analyses at 60 days curing showed that Cr(VI) was predominantly bound as highly insoluble PbCrO(4) that precipitated in the interstitial pores of the soil, with very little to no Cr(VI) associated with the abundant iron oxyhydroxides. Despite its spatial accessibility and due to its low solubility, PbCrO(4) was recalcitrant to treatment, which proceeded only very slowly as judged by the SPLP data. It is concluded that, while CPS has a long residence time in the environment and is a promising reductant, in situ reduction is not an efficient treatment method for soils with highly insoluble Cr(VI) compounds, especially in surficial layers such as the one studied.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.jhazmat.2010.03.052 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Study of the Process of Calcium Sulfide-Based Luminophore Formation from Phosphogypsum.
Molecules
November 2024
Department of Chemical Technologies, Faculty of Technology, Platov South-Russian State Polytechnic University (NPI), Novocherkassk 346428, Russia.
Article Synopsis
- * It explores how phosphogypsum can be transformed into a composite material (CaS/CaSO) using sucrose as an environmentally friendly reducing agent, ultimately enhancing the material's luminescent properties.
- * The characterization of the synthesized materials shows that defects in crystal grids facilitate electron transitions, resulting in luminescence under UV light, indicating potential new applications for recycling industrial waste.
Calcium Sulfide Based Nanophosphors-A Review on Synthesis Techniques, Characterization and Applications.
J Fluoresc
November 2024
CHRIST (Deemed to be University), Bengaluru, 560029, India.
Article Synopsis
- * The review discusses various synthesis methods for CaS nanophosphors, including solvothermal, sol-gel, and microwave techniques, and their impact on the material's effectiveness.
- * It also highlights how adding different dopants can change the emission color of CaS from blue to red, and explores its potential applications in the respective fields, making it a valuable resource for researchers.
Removal of cadmium and zinc by calcium polysulfide in acidic groundwater: Injection ratio and precipitation mechanism.
Chemosphere
September 2024
Department of Civil & Environmental Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea. Electronic address:
In this study, we conducted lab-scale experiments to assess the applicability of calcium polysulfide (CPS) for the removal of cadmium (Cd) and zinc (Zn) from acidic groundwater, with an emphasis on the injection ratio and removal mechanism. For the experiments, CPS was used to treat Cd⁺ and Zn⁺ contaminated solution. Solutions were purged with nitrogen gas, and CPS was injected in an anaerobic chamber.
View Article and Find Full Text PDFNear-infrared-II photocharging nanozyme for enhanced tumor immunotherapy.
J Colloid Interface Sci
December 2024
State Key Laboratory of Metastable Materials Science and Technology, Nano-biotechnology Key Lab of Hebei Province, Applying Chemistry Key Lab of Hebei Province, Heavy Metal Deep-Remediation in Water and Resource Reuse Key Lab of Hebei, Yanshan University, Qinhuangdao 066004, China. Electronic address:
In tumor therapy, copper (Cu)-based nanozymes with peroxidase-like activity play a crucial role in converting hydrogen peroxide into hydroxyl radicals (OH). This process induces immunogenic cell death, which in turn activates the body's immune response, enhancing the efficacy of tumor immunotherapy. Nonetheless, the efficiency of this reaction is curtailed due to the oxidation of Cu(I) to Cu(II), leading to the self-depletion of the nanozyme's activity and an insufficient yield of OH for effective immunotherapeutic activation.
View Article and Find Full Text PDFGas-Amplified Metalloimmunotherapy with Dual Activation of Pyroptosis and the STING Pathway for Remodeling the Immunosuppressive Cervical Cancer Microenvironment.
ACS Nano
May 2024
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, China.
The immunosuppressive microenvironment of cervical cancer significantly hampers the effectiveness of immunotherapy. Herein, PEGylated manganese-doped calcium sulfide nanoparticles (MCSP) were developed to effectively enhance the antitumor immune response of the cervical cancer through gas-amplified metalloimmunotherapy with dual activation of pyroptosis and STING pathway. The bioactive MCSP exhibited the ability to rapidly release Ca, Mn, and HS in response to the tumor microenvironment.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!