Charge Layer Research Articles

Antibacterial polyamide nanofiltration membranes with intermediate layers of quaternized cellulose nanocrystal for Mg2+/Li+ separation

Positively charged and non-toxic intermediate layers are highly desirable for the construction of nanofiltration membranes in the field of Mg2+/Li+ separation. Herein, we have prepared dual-electric layer nanofiltration membranes via introducing positively charged quaternized cellulose nanocrystals (Q-CNC) beyond the negatively charged polyamide skin layers. On the one hand, the strong interactions between Q-CNC and piperazine (PIP) could regulate the thickness, roughness, and residual groups of the polyamide (PA) layers, resulting in improved water flux. On the other hand, the Q-CNC has lots of positive charges which are beneficial for enhancing the rejections of negatively charged polyamide skin layers towards divalent cations since the Donnan and electrostatic effects are long-range forces. Moreover, this effect could be amplified by reducing the thickness of skin layers or decreasing the contents of residual carboxyl groups via adjusting the monomer concentrations. The obtained nanofiltration membranes possess high water flux of 51 L/m2/h/bar, and rejection for MgCl2 of 86 %. The separation factor of Mg2+/Li+ is 29 when the Mg2+/Li+ mass ratio in the feed solution is 20:1. Moreover, the nanofiltration membrane with Q-CNC intermediate layers (QNFM) has good antibacterial properties, showing great potential in the fields of lithium extraction from salt lakes.

The effect of ions on liquid-solid interface investigated by charge sensitive direct current droplet-based electricity generator

The contact electrification (CE) between DI water and SiO2 or fluorinated polymer has been proven to be mainly due to electron transfer, which is significantly influenced by ions in solution. However, how these ions in water affect the charge transfer at the liquid-solid (L-S) interface is still unresolved, especially for the already charged friction layer. Here, a direct current droplet-based electricity generator (DC-DEG) which is sensitive to the change of charge transfer at the L-S interface is adopted to detect the effects of ions in the neutral salt solution on the charged PTFE surface. The distribution of ions on the charged L-S interface (the change of electric potential on the solid surface) and its effects on the output of DC-DEGs have been studied. The results indicate that the charge transfer of droplets and then the output of DC-DEGs are closely related to the concentrations of salt solutions. Anions can enhance the surface potential of PTFE due to their adsorptions on PFTE while cations can reduce it due to their screen effect. At low ionic concentrations, the surface potential enhancement caused by anion adsorption is larger than that surface potential reduction caused by screen effect from cations. At high ionic concentrations, the electrostatic screen effect of cations increases a lot to weaken the surface potential and reducing the charge separation of droplets induced by electrostatic induction (EI). This work explains the redistribution process of ions at the L-S interface and also provides a clever solution for improving the electrical output performance of DEGs.

Mitigating Joule heating in smart nanochannels: Evaluating the efficacy of AC vs. DC fields

This study delves into the profound implications of different electric field types, namely DC and AC with a sinusoidal waveform, on ion transport within intelligent soft nanochannels, aiming to mitigate Joule heating effects. The investigation considers temperature- and concentration-dependent properties and explores their impact on ionic selectivity, rectification factor, Joule heating, and viscosity dissipation in conical soft nanochannels. Operating in both co-current and counter-current modes, the study accounts for the nanochannel's coating with a dense and strongly negatively charged polyelectrolyte layer, addressing the ionic partitioning effect. Numerically solving the Poisson-Nernst-Planck, Navier-Stokes, and energy equations, the study reveals a significant alignment of Joule heating and viscosity dissipation with ionic current, emphasizing the influence of concentration and temperature ratios. Notably, the bidirectional AC field demonstrates a remarkable 85.51% and 71.72% reduction in Joule heating in co-current and counter-current modes, respectively, compared to DC. These findings highlight the significant impact of the AC field on thermal dynamics within nanochannels. In summary, our study offers essential insights into optimizing nanofluidic systems by effectively balancing ion transport efficiency and thermal effects across various electrical field scenarios. These findings directly address the critical challenge of managing Joule heating in intelligent nanochannels, which is essential for enhancing the performance of lab-on-a-chip devices in sensitive biomedical applications.

Neutral and metallic vs. charged and semiconducting surface layer in acceptor doped CeO2

Neutral and metallic vs. charged and semiconducting surface layer in acceptor doped CeO2

Achievement of non-charge layer InGaAs/Si avalanche photodiodes by introducing a groove ring at the bonding interface

The avalanche photodiode (APD) is a prototypical example of a fast and high-gain detector, particularly in the infrared band, where it plays a crucial role in both military and civil optoelectronic devices. The combination of indium gallium arsenide (InGaAs) and silicon (Si) offers an ideal solution for achieving high-performance APDs. For traditional InGaAs/Si APDs, the incorporation of a p-Si charge modulation layer between InGaAs and Si is necessary for electric field modulation. This ensures that a high electric field is maintained in the multiplication layer while keeping it low in the absorption layer. However, the preparation of the p-Si charge modulation layer necessitates a tedious and expensive ion implantation process. Besides, the ion implantation process can also lead to material surface contamination that significantly affects the performance of the device. In this paper, an InGaAs/Si APD without the charge layer is reported. This approach is based on semiconductor direct bonding technology, wherein a groove ring is introduced into the bonding interface to replace the charge layer to regulate the electric field distribution. The electric field of the absorption layer and the multiplier layer is controlled by adjusting the number of grooved rings. By introducing 11 grooved rings into the bonding interface, we achieve a remarkable gain bandwidth product of 88.55 GHz. These findings hold significant implications for the future development of non-charge layer InGaAs/Si APDs with high-gain bandwidth products.

Hierarchical electroactive ion permselective membrane with electrochemical switched ion pump effect for continuous lithium-ion recovery

Highly selective extraction of lithium ions (Li+) from salt-lake brines is crucial to mitigate lithium supply shortages. In this work, a novel electrochemically switched lithium ion permselective membrane (ESLPM) was rationally designed through an ingenious tactic with an electroactive layer of lithium manganate (LiMn2O4) as the active radical and a dense and positively charged polyamide (PA) on each side of polyethersulfone (PES) substrate for the rapid and selective separation of Li+ from salt-lake brines with high Mg/Li ratios. Here, the reversible uptake/release and enhancement electro-sorption selectivity of Li+ are controlled by changing the electrochemical potential of the membrane with an ion-pump effect coupling with the electric field to achieve the continuous recovery of Li+. As a result, the flux of Li+ in the optimum hierarchical ESLPM-240 of the electrochemically switched ion permselective (ESIP) membrane separation system reached 0.032 mol m−2 h−1 for the separation of Li+ from the salt lake brine with a high Mg/Li ratio (Mg2+/Li+ = 20), which is 25% higher than in electrodialysis (ED) system. Meanwhile, by constructing a hierarchical structure, the separation factor of Li+/Mg2+ was increased to 7.8 under the ESIP system, which is about 3.5 times higher that of PA layer, and about 2.2 times higher than that of the electroactive layer. In addition, theoretical calculation confirmed that electroactive LiMn2O4 and positively charged PA layers are more favorable for Li+ transport when compared to Mg2+. Besides, the ESLPM-240 exhibited excellent long-term stability, indicating that the proposed strategy is promising for large-scale industrial applications in the Li+ extraction from salt lakes.

Aggregation of graphene oxide upon the stripping of oxidized debris: An experimental and molecular dynamics simulation study

The most recent structural study of graphene oxide (GO) indicates that the oxidized debris (ODs) adhered to as-prepared GO will strip in certain aquatic settings. The impact of ODs stripping on the characteristics of GO has been widely reported, but its effects on GO aggregation have received less attention. Here, the influence of OD stripping on the GO aggregation property was identified, and the aggregation of as-prepared GO and GO upon OD stripping was compared. Upon ODs stripping, the pKa values of GO shifted from 3.91, 6.25, and 9.84 to 4.54, 6.65, and 10.21, respectively. Further analysis indicated the removal of ODs reduced the net negative charge and improved the hydrophobicity of GO, hence promoting the aggregation of GO. The acceleration of GO-Ca2+-OD aggregate formation was facilitated by the collective effects of ODs stripping, functional group deprotonation, double layer compression, OD bridging, and charge neutralization. The metal ions and stripped ODs attach to GO edges and link GO, which perform like bridges and contribute to further aggregation. In general, the existence of ODs adds complexity to the constructions and characteristics of GO, and it is important to take this into account while evaluating the aggregation characteristic of GO-based materials.

Gain and excess noise properties of 3-gain-stage InGaAs/InAlAs avalanche photodetector

—We constructed a model for a 3-stage InGaAs/InAlAs avalanche photodiode using numerical simulations based on the gain-noise mechanism. The contact layer, barrier layer, charge layer and multiplication layer of this model are optimized accordingly. The performance of the device can be improved by optimizing the thickness and doping concentration of the contact layer, increasing the thickness of the charge layer, and adding a barrier layer. At the same time, the addition of double heterojunction structure makes the performance of the device better, which enables a higher impact ionization rate of the multiplication layer. According to DSMT theory calculation results, the optimized 3-gain-stage device's gain is 90, and the excess noise factor is about 3.1. Compared with the 10-stage avalanche photodiode (with an excess noise factor of 5) studied at the same gain, this work shows higher performance at the lower stage. The optimized structure can provide design and optimization ideas for more stages of avalanche photodiode to increase gain and reduce excess noise.

Ionic liquid with hydrogen bonding reducing leakage charge for enhancing triboelectric performance

Refining the dielectric layer of a triboelectric nanogenerator (TENG) has been shown to maximize its output performance. Among the available strategies, utilizing an ionic dielectric can improve the output performance notably through the internal formation of an electrical double layer (EDL). However, ions dispersed in the ionic dielectric inevitably cause leakage charge between the surface charged layer and electrode of the ionic dielectric; this reduces the charge density, directly affecting output performance. Here, we investigate optimization of the ionic dielectric of a TENG using various ionic liquids (ILs), with the alkyl chain lengths of the cations and fluoride of anions with different size, to achieve power enhancement based on the EDL effect while concurrently suppressing leakage charge via hydrogen bonding. To elucidate the power enhancement working mechanisms within the ionic dielectric, we characterize the chemical, mechanical, and electrochemical properties of the ionic dielectric, including formation of hydrogen bonds, ionic conductivity, and dielectric constant. These parameters are investigated by varying the ion types, molecular sizes, and concentrations of the ILs within the ionic dielectric. As a results, our findings reveal that an IL of OMIM+PF6- dissolved in a base material of thermoplastic polyurethane (TPU) significantly enhances the voltage and current by 2.3 and 2.9 times, respectively, compared to those of a conventional TENG with TPU. These findings are expected to be implemented across a wide range of TENGs, paving the path for their advanced applications in next-generation energy harvesting.

Unidirectional gene delivery electrospun fibrous membrane via charge repulsion for tendon repair

Gene therapy is capable of efficiently regulating the expression of abnormal genes in diseased tissues and expected to be a therapeutic option for refractory diseases. However, unidirectional targeting gene therapy is always desired at the tissue interface. In this study, inspired by the principle that like charges repulse each other, a positively charged micro-nano electrospun fibrous membrane with dual-layer structure was developed by electrospinning technology to achieve unidirectional delivery of siRNA-loaded cationic nanocarriers, thus realizing unidirectional gene therapy at the tendon-paratenon interface. Under the charge repulsion of positively charged layer, more cationic COX-2 siRNA nanocarriers were enriched in peritendinous tissue, which not only improved the bioavailability of the gene drug to prevent the peritendinous adhesion formation, but also avoided adverse effects on the fragile endogenous healing of tendon itself. In summary, this study provides an innovative strategy for unidirectional targeting gene therapy of tissue interface diseases by utilizing charge repulsion to facilitate unidirectional delivery of gene drugs.

Protonic and electronic hole conductivity of grain interior and grain boundaries in BaZr0.9Y0.1O3-δ: Effect from sample processing

BaZr0.9Y0.1O3-δ (BZY10) is a popular composition for the electrolyte in protonic ceramic cells, due to its relatively high proton conductivity, excellent chemical stability, and good compatibility with NiO negatrode substrate during high temperature co-sintering. The microstructure of BZY10 is highly dependent on sample processing, leading to large discrepancy of the electrochemical performance of BZY10 in literature. In this work, three BZY10 samples were prepared by different sample processing and sintering conditions, and the grain interior (bulk) and grain boundary partial conductivities of protons and holes were separated. The sintering processes influenced the transport properties of pristine BZY10 samples significantly, and longer sintering time at high temperature (1650 – 1700 °C) leads to lower proton conductivity in both bulk and grain boundary. However interestingly, longer sintering time resulted in higher ionic transport number of bulk conduction, but lower ionic transport number of grain boundary conduction, possibly due to increasing Ba-deficiency in bulk by longer annealing at high temperature. Besides, adding ZnO into BZY10 decreased the proton conductivity in both bulk and grain boundary, but its ionic transport number of bulk conduction increases. A further analysis based on the theory of space charge layer indicated that adding ZnO leaded to decreased Schottky barrier height in the grain boundary core, and the highest Schottky barrier height was observed in the pristine sample which was sintered for longer time. The results obtained in this work suggest a potential strategy to regulate the transport properties of BZY10 by choosing appropriate approaches for sample processing to control the microstructure and local composition of the polycrystalline BZY10 ceramic electrolyte.

Performance evaluation of an eco-friendly and highly efficient FASnI3-based perovskite solar cell using Mg-doped CuCrO2 as HTL

Perovskite-based solar cells have emerged as promising photovoltaic devices. However, challenges involving unstable and toxic materials hinder their commercial use. Addressing these issues, the investigation incorporates a non-toxic tin-based absorber layer and specific inorganic charge transporter materials. The focus is on formamidinium tin iodide (FASnI3) based perovskite solar cells (PSCs), known for their efficiency, lead-free composition, and environmental friendliness. Zinc oxy-sulphide (ZnO0.25S0.75) serves as the electron transport layer (ETL) due to its 3.03 eV band gap. Magnesium doped copper delafossite (Mg–CuCrO2) acts as the hole transport layer (HTL) for its 3.3 eV band gap and its ability to maintain device stability. The proposed structure Au/Mg–CuCrO2/FASnI3/ZnO0.25S0.75/TCO was analyzed using numerical simulation conducted with the solar cell capacitance simulator (SCAPS-1D). Performance parameters of the structure were assessed by varying FASnI3 absorber layer thickness, defect density, and doping concentration. Variations in ETL and HTL thickness, defect density, and electron affinity were also explored. Effects of interface defects, series resistance, shunt resistance, and temperature on the device were examined. The optimized device achieved Voc of 1.2462 V, Jsc of 27.98 mA/cm2, FF of 89.33%, and PCE of 31.16%. This level of efficiency holds significant promise as an alternative for a highly effective environmentally friendly solar absorber material in photovoltaic applications.

N-octyltrimethylammonium bromide-assisted self-assembly of CoMo precursors to prepare CoMoS/Al2O3 catalysts for highly selective hydrodesulfurization of thiophene

A novel (C11H26N)2Co(MoS4)2 complex was prepared via the n-octyltrimethylammonium bromide-assisted self-assembly of CoMo precursors for the selective hydrodesulfurization (HDS) of thiophene. The complex was generated by the interaction between the negatively charged CoMo compound and the positively charged n-octyltrimethylammonium ions. Then positively charged bimolecular layers were formed owing to van der Waals forces between the C11H26N+ and the complex, and they were anchored on the negatively charged γ-Al2O3. Compared with CoMoS/γ-Al2O3 catalysts prepared by impregnation, the optimal CoMoN-0.3/γ-Al2O3 catalyst exhibited better performance for selective HDS due to the enhanced Mo dispersion, the close contact between Co and Mo, and the increased amount of CoMoS phases on γ-Al2O3. Among these catalysts, the optimal CoMoN-0.3/γ-Al2O3 catalyst with the highest concentration of CoMoS phases exhibited the highest HDS reaction rate constant of 6.95 × 10-6 mol·g−1·s−1 and the best selective factor of 26.1 for the selective HDS of thiophene with 1-hexene.

Influence of the liquid ionic strength on the resonance frequency and estimated shell parameters of lipid-coated microbubbles

Measurement of the resonance frequency and shell properties of coated microbubbles (MBs) is important in understanding and optimizing their response to ultrasound. In many applications MBs are in ionic liquids; however, the influence of the medium charges on the MB behavior is not well investigated. This study aims to measure the medium charge interactions with MBs by measuring the frequency-dependent attenuation of the same size MBs in mediums of varying charge density. In-house lipid-coated MBs were size isolated to a mean size of 2.35 μm using differential centrifugation. MBs were suspended in distilled water (DW), Phosphate-Buffered Saline solution (PBS1×) and PBS10×. The frequency-dependent attenuation of the MBs solutions was measured using a system of two aligned 100% bandwidth transducers with 10 MHz center frequency. The MB shell properties were estimated by fitting the linear equation to experiments. With increasing salinity, the frequency of the peak attenuation decreased (13, 7.5 and 6.25 MHz in DW, PBS1× and PBS-10×, respectively) and attenuation peak increased (∼140%). Estimated MBs shell elasticity decreased by 64% between DW and PBS-1× and 36% between PBS-1x and PBS-10x. The estimated shell viscosity reduced by ∼40% between DW and PBS-1× and 42% between PBS-1× and PBS-10×. The significant reduction in the fitted stiffness and viscosity is possibly due to the formation of a densely charged layer around the shell and requires proper inclusion in the related MB models.

Stable hydrogen and oxygen isotope geochemistry of Fe3+-rich, interstratified clay minerals from seafloor hydrothermal sites

Chemical and structural complexities in interstratified clay minerals arising from mineral transformations and evolving formation conditions should be recorded in their stable isotope signatures. This paper examines the controls on the stable hydrogen and oxygen isotope compositions of Fe3+-rich, glauconite-nontronite, talc-nontronite and talc-saponite from submarine hydrothermal sites, with a focus on the Red Sea Atlantis II Deep. Values of δ18O became less positive in the order nontronite > glauconite-nontronite > talc-nontronite > talc-saponite, yielding oxygen isotope temperatures ranging from ∼40 °C for nontronite to ∼135–300 °C for talc-saponite. These clay minerals have low δ2H, ranging from −145 to −127‰ for talc-nontronite, −135‰ for nontronite, −129 to −85‰ for glauconite-nontronite, and −95 to −59‰ for talc-saponite. The clay mineral-water hydrogen isotope fractionation is strongly affected by Fe3+ content, with increasing structural Fe3+ causing progressive weakening of O-H bonds. The large ionic radius and high charge of Fe3+ cause it to be more poorly shielded by surrounding oxygen from hydroxyl hydrogen relative to other octahedral or tetrahedral cations. The resulting lengthening of O-H bonds favours 1H over 2H. Our results confirm that Fe-rich phases, such as nontronite-glauconite, are produced at the lowest temperatures and Mg-rich phases, such as talc-saponite, are formed at the highest temperatures in seafloor hydrothermal environments. Evolving fluid chemistry and fluid pathways during clay mineral formation are also important. Glauconite layer formation from precursor nontronite likely occurred during diagenesis; redox changes causing Fe-reduction and an increase in layer charge facilitated interlayer K-fixation. Talc-saponite compositions vary with temperature and fluid chemistry, forming at variable sediment depths depending on access to the hottest hydrothermal fluids.

Enhanced ammonium removal and recovery from wastewater using an innovative redox-active flow electrode: The significant role of redox charge compensation and hydrogen bond network reconstruction

Flow-electrode capacitive deionization (FCDI) is an ideal electrochemical technology for NH4+ recovery but suffers from inefficient charge transfer, leading to high energy consumption and unsatisfactory recovery performance. In this study, we developed an innovative redox-active flow electrode (RAFE) comprising redox-active electrolyte ((NH4)3Fe(CN)6) and activated carbon (AC) to enhance the removal and recovery of NH4+. The ion capture and charge transfer mechanism of NH4+ within this electrode were further investigated. FCDI with RAFE cathode exhibited a rapid removal (31 mgN/m2/min) and recovery rate (26 mgN/m2/min), with about 32 % increment as compared to the FCDI with AC cathode. The lower removal (2.3 kWh/kgN) and recovery energy consumption (5.76 kWh/kgN) were also achieved. The CV curves and electrode characterization indicated that NH4+ was capacitive captured and released through electric double layer (EDL) and redox charge compensation. Dynamic charge efficiency analysis showed that EDL capacitive capture mechanism plays a dominant role during the charging stage while the redox compensation capture mechanism dominated the charge transfer during the discharging stage. Moreover, electrode suspension characterization demonstrated that the migration of NH4+ was facilitated by hydrogen bond network reconstruction. This work provided an energy-saving system for efficient NH4+ removal and recovery by coupling FCDI with RAFE cathode.

High‐Capacity, Long‐Life Sulfide All‐Solid‐State Batteries with Single‐Crystal Ni‐Rich Layered Oxide Cathodes

AbstractSulfide all‐solid‐state battery (SASSB) with ultrahigh‐nickel layered oxide cathode (LiNixCoyMn1‐x‐yO2, NCM, x ≥ 0.9) offers the potential of high energy density and safety for superior energy storage systems. However, stable cycling is difficult to realize due to adverse interfacial reactions, space charge layer (SCL), and elemental diffusion. Herein, a straightforward solid‐phase coating strategy is exploited to synthesize Ni90‐S cathode, which greatly improves the charge transmission capability of the composite cathode and suppresses interfacial reactions in SASSB. The consequent SC‐Ni90‐0.2%S/Li6PS5Cl/Li4Ti5O12 SASSB exhibits enhanced electrochemical performance, including a long life of 500 cycles with 87% capacity retention at 1C, high areal capacity of 11.44 mAh cm−2, and excellent rate performance at 20 C. These results promise an efficient strategy for designing cathode materials for SASSBs.

Unraveling the evolution of Cathode–Solid electrolyte interface using operando X-ray Photoelectron spectroscopy

Understanding the evolution of the solid electrolyte-electrode interface is currently one of the most challenging obstacles in the development of solid-state batteries (SSBs). Here, we develop an X-ray Photoelectron Spectroscopy (XPS) that allows for operando measurement during cycling. Based on theoretical analysis and the modulated electrode and detector co-grounding mode, the displacement of binding energy can be correlated with the surface electrostatic potential of the material, revealing the charge distribution and composition evolution of the space charge layer between the cathode and the electrolyte. In the investigation of typical LiCoO2 (LCO)/Li6PS5Cl (LPSC)/Li–In batteries, we observed the static potential difference and oxidative decomposition between LPSC and LCO, and the effectiveness of the LiNbO3 coating in reducing potential difference and inhibiting the diffusion of Co and oxidation of S species. Furthermore, our study also revealed that the potential drop between LiNi0·8Co0·1Mn0·1O2 and LPSC is smaller than that of LCO, whilst that between Li3InCl6 and LCO remains near zero. The proposed operando XPS method offers a novel approach for real-time monitoring of interface potential and species formation, providing rational guidance for the interface engineering in SSBs.

Functionalization of reduced montmorillonite as an adsorbent toward aqueous anion: role of layer charge density

Montmorillonite (Mt) is widely used in various fields due to its abundant resources and excellent adsorption performance, while the hydration and adsorption properties of raw or functionalized Mt are affected by its intrinsic property, layer charge density (LCD). Herein, a series of reduced-charge montmorillonites (RC-Mt) with high, medium, and low layer charges were prepared by the method of lithiation and microwaving Ca-Mt. Meanwhile, the effects of artificially regulated layer charge density on Mt’s structure, hydration properties, and the removal ability of aqueous anions by the poly (diallyl dimethylammonium chloride) functionalized Mt (PDDA-Mt) were also investigated. Results showed that the LCD of Mt decreased with the increasing microwave time or power. In addition, the physicochemical properties of RC-Mt which included cation exchange capacity (CEC), colloidal index, and swelling properties decreased as the LCD decreased. Furthermore, the adsorption capacity of Mt for NO3- was significantly improved following the PDDA functionalization. The kinetic modeling suggests that the Pseudo-first-order model better characterized the adsorption of Ca-Mt and Li-Mt than the Pseudo-second-order model. On the other hand, the good fit of the Pseudo-second-order model implied that the adsorption process of nitrate on RC-Mt and PDDA-Mt is mainly driven by chemisorption control. The adsorption thermodynamics indicated that the adsorption process was spontaneous. Furthermore, the FTIR and XPS results suggested that in addition to diffusion and electrostatic interactions, the adsorption mechanism of PDDA-Mt was mainly attributed to the ion exchange between chloride and nitrate on the quaternary ammonium group of PDDA.

Adsorption study of the charge distribution features of highly charged smectites

The study examines the results of assessing the charge density distribution of smectite layers from the bentonite province of the Republic. Kazakhstan (Taganskoye and Dinosaurovoye fields) by alkylammonium method. The method is based on the study of the interaction of a homologous series of fatty amines with the surface of smectites. Organic cations form monomolecular and bimolecular adsorption layers on the basal surfaces. This allows the analysis of the dependence of the position of the diffraction maximum in the small-angle region on the bounding area of the organic cation and to obtain the charge density distribution over the smectite layers. The results obtained for the studied samples show a similar composition of montmorillonite: in all cases, smectites were characterized by a significant charge density with a different proportion of highly charged layers (cation exchange capacity – 120-130 mEq/100 g). The obtained data on charge distribution were compared with some adsorption and colloid-chemical characteristics of smectites, including the values of their cation exchange capacities. At the same time, such technological parameters as the effective viscosity of aqueous dispersions, despite the close charge distribution, differed significantly and showed a sharp dependence on the proportion of sodium cations in the exchange complex.