Experimental investigation and optimization of supercritical carbon dioxide extraction of toxic heavy metals from solid waste using different modifiers and chelating agents

Ghoreishi, S.M.; Hedayati, Ali; Ansari, Kazem

doi:10.1016/j.supflu.2016.06.012

Cited by 28 publications

(3 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The higher value of the constant, the better is the activation effect [36][37][38]; for example, the values for Cd-EDTA and Cd-GLDA (16.5 and 10.31, respectively) are higher than that for Cd-CA (7.9). Furthermore, the activation effect of chelating agents is also closely related to the type of heavy metal [39]. We, accordingly, noted the significant differences in the activation effects for the three heavy metals in the present study.…”

Section: Discussionsupporting

confidence: 62%

Comparative Activation Process of Pb, Cd and Tl Using Chelating Agents from Contaminated Red Soils

Liu

Luo

Yao

et al. 2020

IJERPH

View full text Add to dashboard Cite

Adding chelating agents is a critical technique of heavy metal activation for enhancing phytoextraction through the formation of soluble metal complexes which will be more readily available for extraction. The preliminary, dynamic, equilibrium activation experiments and speciation analysis of Pb, Cd and Tl in contaminated red soils were used to select six chelates with relatively good activation performance from nine chelates, and the effects of dosage and pH on the heavy metals activation were studied systematically. Results showed that the activation of Pb, Cd and Tl by chelates reached equilibrium within 2 h, and the activation process showed three stages. Under neutral conditions, chelates had better activation performance on Pb- and Cd-contaminated soils. Except for S,S-ethylenediamine disuccinic acid (S,S-EDDS) and citric acid (CA), the maximum equilibrium activation effect (MEAE) of ethylenediaminetetraacetic acid (EDTA), N,N-bis (carboxymethyl) glutamic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA) and aminotriacetic acid (NTA) was over 81%. The MEAE of Tl-contaminated soil was less than 15%. The decreasing order of the dosage of chelating agents corresponding to MEAE for three types of contaminated soils was Pb-, Cd- and Tl-contaminated soil, relating to the forms of heavy metals, the stability constants of metal–chelates and the activation of non-target elements Fe in red soil. Under acidic conditions, the activation efficiencies of chelates decreased to differing degrees in Pb- and Cd-contaminated soils, whereas the activation efficiencies of chelating agents in Tl-contaminated soils were slightly enhanced.

show abstract

Section: Discussionsupporting

confidence: 62%

Comparative Activation Process of Pb, Cd and Tl Using Chelating Agents from Contaminated Red Soils

Liu

Luo

Yao

et al. 2020

IJERPH

View full text Add to dashboard Cite

show abstract

“…The objective is to understand the interaction among various parameters and the optimization of the operating conditions to obtain the best response, simultaneously 19 . RSM is a useful tool which has been widely applied successfully in several fields for the optimization of operating parameters in various processes [20][21][22] .…”

Section: Fig 4: the Flow Sheet Of The Electrothermal Fluidized Bed Cmentioning

confidence: 99%

Untitled

2017

IJPSR

View full text Add to dashboard Cite

Zirconium tetrachloride was produced in a pilot plant fluidized bed reactor via the carbochlorination reaction of zirconia. Minitab software 17 was used for the design of experiment with response surface methodology (RSM) for both semi batch and continuous processes. The operating temperature (800-1200 °C), reaction time (30-90 min) and mean particle size (MPS) (70-130µm) were chosen as the range of operating conditions at semi-batch mode. Also, the ranges of operating variables at the continuous mode were chosen to be the operating temperature(1000-1400°C), chlorine concentration (3-5mol/m 3 ) and mean particle size (MPS) (70-130µm). The coefficients of determination (R 2 ) for semi-batch and continuous modes by RSM analysis were 99.54% and 99.94%, respectively. The optimal operating conditions was predicted to be the Cl 2 concentration of 3mol/m 3 , temperature of 1380 °C and the mean particle size of 70µm in which the maximum chlorine conversion of 98.26% was obtained at continuous process. The optimum operating conditions for semi-batch process were found by using RSM modelling to be 1200°C, 90 min and 70 µm, in which the maximum zirconia conversion of 92.7% was obtained.

show abstract

“…The addition of co-solvents to supercritical carbon dioxide (sCO 2 ) improves the efficiency of solution phase processes such as metal extraction. − In this case, simple alcohols (e.g., MeOH) form molecular clusters − that enhance the solubility of chelating ligands and metal–ligand complexes. , The behavior of co-solvent clusters and their size distribution are fundamentally important in sCO 2 chemistry. Nuclear magnetic resonance spectroscopy (NMR) has proven useful in the description of the behavior and size distribution of co-solvent clusters. ,,,, Established strategies for evaluating alcohol cluster distributions include the use of the ensemble hydroxyl chemical shift, which is measured as a mass average due to fast proton exchange between clusters compared to the timescale of the NMR measurement .…”

Section: Introductionmentioning

confidence: 99%

Alcohol Clustering Mechanisms in Supercritical Carbon Dioxide Using Pulsed-Field Gradient, Diffusion NMR and Network Analysis: Feedback on Stepwise Self-Association Models

et al. 2019

View full text Add to dashboard Cite

Co-solvent clustering in complex fluids is fundamental to solution phase processes, influencing speciation, reactivity, and transport. Herein, methanol (MeOH) clustering in supercritical carbon dioxide is explored with pulsed-field gradient, diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY-NMR), and molecular dynamics (MD) simulations. Refinements on the application of self-association models to DOSY-NMR experiments on clustering species are presented. Network analysis of MD simulations reveals an elevated stability of cyclic tetrameric clusters across MeOH concentrations, which is consistent with experimental DOSY-NMR molecular cluster distributions calculated with self-association models that include both cooperative cluster assembly and entropic penalties for the formation of large clusters. Simulations also detail the emergence of cluster-assembly and cluster-disassembly reactions that deviate from stepwise monomer addition or removal. This combination of experiment, simulation, and novel analyses facilitates refinement of models that describe co-solvent aggregation with far-reaching impact on the prediction of solution phase properties of complex fluids.

show abstract

Experimental investigation and optimization of supercritical carbon dioxide extraction of toxic heavy metals from solid waste using different modifiers and chelating agents

Cited by 28 publications

References 28 publications

Comparative Activation Process of Pb, Cd and Tl Using Chelating Agents from Contaminated Red Soils

Comparative Activation Process of Pb, Cd and Tl Using Chelating Agents from Contaminated Red Soils

Untitled

Alcohol Clustering Mechanisms in Supercritical Carbon Dioxide Using Pulsed-Field Gradient, Diffusion NMR and Network Analysis: Feedback on Stepwise Self-Association Models

Contact Info

Product

Resources

About