Fine tuning of pore architecture and morphology of stiffened Zeolitic Imidazolate Frameworks synthesized using fast current driven method and mixed ligand strategy

2021 ◽  
Vol 327 ◽  
pp. 111409
Author(s):  
P. Utpalla ◽  
S.K. Sharma ◽  
J. Mor ◽  
J. Prakash ◽  
J. Bahadur ◽  
...  
2022 ◽  
Author(s):  
Javier Lopez-Cabrelles ◽  
Eugenia Miguel-Casañ ◽  
Maria Esteve-Rochina ◽  
Eduardo Andres-Garcia ◽  
Inigo Vitorica-Yrzebal ◽  
...  

Different mixed-ligand Zeolitic Imidazolate Frameworks (ZIFs) with sodalite topology, i.e. isoreticular to ZIF-8, unachievable by conventional synthetic routes, have been prepared using a solvent-free methodology. In particular, the versatility of...


2021 ◽  
Author(s):  
Chompoonoot Nanthamathee ◽  
Chantamalinee Chantarangkul ◽  
Chanida Jakkrawhad ◽  
Apirak Payaka ◽  
Pongsathorn Dechatiwongse

Abstract Mixed ligand synthetic approach offers an alternative to engineer a specific character in metal-organic framework (MOFs) materials. Herein, we synthesized and characterized a well-known prototype zirconium based-MOF, so called UiO-66 and its mixed ligand derivatives UiO-66-xATA, where x is mole fraction (0.5, 0.75 and 1.0) and ATA is 2-animoterephthalate. The aim of the study is to observe whether the dye adsorption capacity can be tuned/enhanced by the ATA ligand substitution into the framework. We found that, at room temperature, UiO-66-0.75ATA shows the highest adsorption capacity toward various dye solution including methylene blue (MB), indigo carmine (IC) and congo red (CR). The optimum adsorption conditions in all four materials were found to be in a common trend where their adsorption capacities can be increased with decreasing pH and adsorbent dose, increasing of IC concentration, contact time and temperature. Pseudo-second order kinetics model fits best with their adsorption data, where UiO-66-ATA has the fastest rate of adsorption. Langmuir and Freundlich isotherms were found to best describe adsorption behaviour in ATA-containing UiO-66 and UiO-66 respectively, where adsorption processes were found to be physisorption. Confirming by thermodynamic studies, the adsorption in all four materials occurred spontaneously, driven by entropy. Computational studies showed ligand to metal charge transfer where the distribution of electron densities was varied with the amount of functionalized ligand. Adsorption mechanism is proposed as a synergistic interplay between electrostatic interaction and hydrogen bonding. The findings in this work broaden potential strategy to fine-tune the dye adsorption capacity in MOF materials.


ASHA Leader ◽  
2017 ◽  
Vol 22 (6) ◽  
Author(s):  
Christi Miller
Keyword(s):  

2012 ◽  
Vol 82 (3) ◽  
pp. 216-222 ◽  
Author(s):  
Venkatesh Iyengar ◽  
Ibrahim Elmadfa

The food safety security (FSS) concept is perceived as an early warning system for minimizing food safety (FS) breaches, and it functions in conjunction with existing FS measures. Essentially, the function of FS and FSS measures can be visualized in two parts: (i) the FS preventive measures as actions taken at the stem level, and (ii) the FSS interventions as actions taken at the root level, to enhance the impact of the implemented safety steps. In practice, along with FS, FSS also draws its support from (i) legislative directives and regulatory measures for enforcing verifiable, timely, and effective compliance; (ii) measurement systems in place for sustained quality assurance; and (iii) shared responsibility to ensure cohesion among all the stakeholders namely, policy makers, regulators, food producers, processors and distributors, and consumers. However, the functional framework of FSS differs from that of FS by way of: (i) retooling the vulnerable segments of the preventive features of existing FS measures; (ii) fine-tuning response systems to efficiently preempt the FS breaches; (iii) building a long-term nutrient and toxicant surveillance network based on validated measurement systems functioning in real time; (iv) focusing on crisp, clear, and correct communication that resonates among all the stakeholders; and (v) developing inter-disciplinary human resources to meet ever-increasing FS challenges. Important determinants of FSS include: (i) strengthening international dialogue for refining regulatory reforms and addressing emerging risks; (ii) developing innovative and strategic action points for intervention {in addition to Hazard Analysis and Critical Control Points (HACCP) procedures]; and (iii) introducing additional science-based tools such as metrology-based measurement systems.


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