Article
Chemistry, Physical
Stephan Kaufhold, Reiner Dohrmann, Jens Groeger-Trampe
Summary: The study investigates the liberation of naturally present fixed cations in pure dioctahedral smectites. The results show that hydrothermal treatment can render at least a part of the fixed cations exchangeable. However, this liberation is accompanied by a decrease in cation exchange capacity, which may be due to smectite dissolution. The fixed cations are strongly bound and can only be liberated if the smectite structure is affected.
APPLIED CLAY SCIENCE
(2023)
Article
Agriculture, Dairy & Animal Science
Yosra Soltan, Amr Morsy, Nesrein Hashem, Mahmoud Elazab, Mohamed Sultan, Haneen Marey, Gomaa Abo El Lail, Nagwa El-Desoky, Nourhan Hosny, Ahmed Mahdy, Elsayed Hafez, Sobhy Sallam
Summary: The study showed that two types of modified nano-montmorillonite developed by ion-exchange reactions using different surfactants could effectively reduce methane emissions from ruminants. Among them, the clay modified by cationic surfactant was more efficient in modulating rumen fermentation properties.
Article
Geochemistry & Geophysics
Afonso D. Macheca, Antonio B. Mapossa, Antonio J. Cumbane, Asmina E. Sulemane, Shepherd M. Tichapondwa
Summary: This study investigates the Na2CO3 activation of calcium bentonite clay and evaluates the influence of different conditions on its ion exchange capacity. The results demonstrate that the concentration of Na2CO3, activation temperature, and activation time significantly affect the ion exchange capacity and Na/Ca ratio of the clay. The experimental findings further confirm the structural and property changes of the calcium bentonite clay after activation.
Article
Chemistry, Physical
Jason W. Stuckey, Jovan Livada, Carmen Enid Martinez
Summary: Clay minerals, especially Na-2-mica, have high selectivity for copper sorption and show potential for remediating contaminated water and surface soils. Na-2-mica exhibits strong resistance to copper desorption due to strong Cu retention mechanisms, while montmorillonite reversibly retains copper ions.
APPLIED CLAY SCIENCE
(2022)
Article
Geochemistry & Geophysics
Fernando H. do Nascimento, Jorge C. Masini
Summary: This paper demonstrates that intercalating Na+ homoionic vermiculite with Fe3+ polyhydroxy cations significantly improves the affinity of the clay mineral-based sorbent toward phosphate. Kinetic experiments show fast adsorption, reaching equilibrium within about 200 minutes of contact time, with intraparticle diffusion being the rate-limiting step. Adsorption isotherms fit well with the Freundlich equation and a two-site Langmuir model, indicating heterogeneity of adsorption sites. The separation factor derived from the Langmuir constant reveals favorable and even irreversible adsorption for high-affinity minor adsorption sites. The adsorption capacity is similar to other clay-based phosphate adsorbents and can remove about 71% of available phosphate in reservoir water spiked with 10 mg L-1 P.
Article
Chemistry, Physical
Nithya Subramanian, Laura Nielsen Lammers
Summary: This study examines the energetics of swelling and ion exchange reactions in montmorillonite, revealing the influence of solution and clay composition on the spontaneity of the reactions. The results show that the clay tends to collapse to lower hydration states as the solution concentration increases. Changes in equilibrium water content and the composition of the mixed electrolyte solution play critical roles in driving ion exchange and clay selectivities to the exchanged cation.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Chemistry, Physical
Po-Hsiang Chang, Pan Liu, Binoy Sarkar, Raj Mukhopadhyay, Qing-Yuan Yang, Yu-Min Tzou, Bo Zhong, Xuxiang Li, Gary Owens
Summary: The study of Amitriptyline (AMI) adsorption on montmorillonite revealed that the best adsorption occurred at neutral pH, following a pseudo-second order kinetic model. The cation exchange mechanism was identified as the main adsorption mechanism.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2021)
Article
Chemistry, Physical
Ziyi Meng, Yuxi Zou, Ningning Li, Bei Wang, Xudong Fu, Rong Zhang, Shengfei Hu, Xujin Bao, Xiao Li, Feng Zhao, Qingting Liu
Summary: The performance of Nafion-based proton-exchange membrane fuel cells (PEMFCs) is significantly reduced at low relative humidities, requiring external humidification. To address this issue, a graphene oxide (GO)-intercalated microbial montmorillonite (mMMT) layered stack (GO@mMMT) was developed to improve the proton conductivity of Nafion membranes under low humidity and high temperature conditions. The GO@mMMT/Nafion composite membrane exhibited excellent proton conductivity at various humidities, with a significant increase compared to the recast Nafion membrane. The assembled single cell demonstrated higher peak power density, indicating the potential of Nafion composite membranes with GO@mMMT incorporated layered stacks for PEMFC applications with simplified water management.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Geoffrey M. Bowers, Sydney S. Cunniff, H. Todd Schaef, Sarah D. Burton, Eric D. Walter, David W. Hoyt, John S. Loring
Summary: This paper examines the interaction between wet and dry supercritical CO2 and saturated smectite clays, and finds that the polarizability of the charge-balancing cation plays an important role in determining the interlayer fluid properties and smectite expansion.
Article
Chemistry, Physical
J. Theo Kloprogge, Concepcion P. Ponce, Danilo O. Ortillo
Summary: XPS analysis of layered clay systems with intercalated inorganic and organic compounds reveals valuable insights into the structure, coordination, and oxidative transformations of these compounds. By studying the shifts in binding energies and multiplet splitting, XPS can track changes in oxidation states and coordination environments within the materials.
Article
Biochemistry & Molecular Biology
Issaka Garikoe, Boubie Guel, Ingmar Persson
Summary: This study investigates the arrangement of bisphenol A molecules in organoclays and their interactions with intercalated surfactants. The results show that bisphenol A is adsorbed between the alkyl chains of the surfactant in the interlayers of organoclays, leading to the expansion of the clay structure.
Article
Multidisciplinary Sciences
Kerem Ilaslan, Fatih Tornuk
Summary: In this study, organomodified montmorillonite and halloysite nanoclays were used to enhance intercalation characteristics, and Ag+ ions were doped to enhance antimicrobial properties. Various analyses showed that the interlayer space of the nanoclays increased and Ag+ ions successfully doped into the nanoclay structure. Additionally, MMT-type nanoclay samples released more Ag+ ions compared to halloysite-type nanoclay samples. The results demonstrated that intercalated and Ag+-doped nanoclays effectively inhibited bacterial growth.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2023)
Article
Environmental Sciences
Simon Weldon, Bert van der Veen, Eva Farkas, Nazli Pelin Kocaturk-Schumacher, Alba Dieguez-Alonso, Alice Budai, Daniel Rasse
Summary: This study conducted a quantitative analysis of the sources of variability in NH4+ sorption to biochar and identified which biochar traits are more favorable for high sorption capacity. The results showed that unmodified biochar has lower sorption capacity for NH4+ than previously reported, and activation can improve sorption capacity but to a limited extent. Methodology, such as pH control and ash removal, significantly affected sorption estimates.
Article
Chemistry, Multidisciplinary
Kristoffer W. Bo Hunvik, Patrick Loch, Dirk Wallacher, Alexsandro Kirch, Leide P. Cavalcanti, Martin Riess, Matthias Daab, Vegard Josvanger, Sven Graetz, Fabiano Yokaichiya, Kenneth Dahl Knudsen, Caetano Rodrigues Miranda, Josef Breu, Jon Otto Fossum
Summary: The research reveals that as the interlayer surface charge in clay minerals decreases, the adsorption capacity for CO2 increases and the pressure threshold for adsorption and swelling in response to CO2 decreases. Different layer charges in clay minerals exhibit varying CO2 adsorption capacities and release mechanisms.
Article
Chemistry, Physical
Po-Hsiang Chang, Raj Mukhopadhyay, Chien-Yen Chen, Binoy Sarkar, Jiwei Li, Yu-Min Tzou
Summary: The adsorption behavior of ranitidine hydrochloride on Ca-montmorillonite was studied. The results showed that Ca-montmorillonite had a high adsorption capacity for ranitidine hydrochloride, and the adsorption kinetics followed the pseudo-second order equation. Cation exchange was identified as the dominant mechanism of adsorption. The study also found that the molecular structure of ranitidine hydrochloride could cause irregular changes in the basal spacing of swelling type clay minerals.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)