Reverse Ion Research Articles

Hydrogeochemical assessment and groundwater quality in a shallow aquifer: A case study of San Luis Potosí Valley, Mexico

The chemical composition of groundwater is the product of the evolution and incorporation of major ions, the product of natural hydrogeochemical processes or human interference that occurs in an aquifer. To establish the hydrogeochemical groundwater characteristics and suitability, 47 samples were collected from shallow wells in the study area. The objective was to determine the hydrogeochemical assessment of the groundwater in the shallow aquifer and establish the water quality and pollution associated with the dissolved organic matter in the San Luis Potosí sub-basin. The water quality assessment has been carried out by evaluating the physicochemical parameters such as temperature, pH, EC, TDS, and the main ions, which present the following trend: Ca2+>Na+>K+>Mg2+, HCO3− > SO42− > Cl− > NO3. The type of water in the area is mainly of four types: Ca–Na–HCO3–Cl (32%), Ca–Na–SO4–HCO3 (19%), Na–Ca–HCO3–Cl (13%), Ca–Na–HCO3–SO4 (11%). The content of NO3− (4.0–50.0 mg L−1), NH4+ (0.03–40.0 mg L−1), SO42− (20.0–276.0 mg L−1) y PO43− (0.01–45.5 mg L−1) indicate contamination that may come from inorganic and organic matter. Organic matter of anthropogenic origin was identified by 3D fluorescence. The results of this study demonstrate that the main processes that affect and control the chemical composition of the water in the shallow aquifer of SLP are silicate weathering, albite weathering, and reversible ion exchange.

Triggering hollow carbon nanotubes via dual doping for fast pseudocapacitive potassium-ion storage

Heteroatom doping is effective to adjust the active site, ion transportation and electronic transfer in carbonaceous materials for electrochemical energy storage. Herein, we report hollow carbon nanotubes (HCNT) co-doped with boron and nitrogen for fast potassium-ion storage. With the doping level of (B = 13.4 at.%, N = 14.3 at.%), HCNT anodes display unique performance merits: large specific capacity (383 mA h g−1 at 0.02 A g−1), enhanced rate capability (189 mA h g−1 even at 1.0 A g−1) and improved cycling stability (capacity remaining 70% after 500 cycles at 1.0 A g−1). In-situ Raman and ex-situ morphology investigations demonstrate a highly reversible evolution in G and D bands of HCNT and confirm the sturdy structure for highly reversible potassium ion storage. Further electrochemical kinetics analyses reveal the dominated capacitive potassium-storage process with a high average K+ diffusion coefficient. These findings enrich the understanding of the heteroatom doping engineering in carbons for potassium-ion batteries.

Probing Distinctive Redox Mechanism in Ni-Rich Cathode Via Real-Time Quick X-Ray Absorption Spectroscopy.

X-ray radiation damage on the measuring system has been a critical issue regularly for a long-time exposure to X-ray beam during the in operando characterizations, which is particularly severe when the applied X-ray energy is near the absorption edges (M, L, K, etc.) of the interest element. To minimize the negative effects raised by beam radiation, we employ quick X-ray absorption spectroscopy (QXAS) to study the electrochemical reaction mechanism of a Ni-rich layered structure cathode for lithium-ion batteries. With the advanced QXAS technique, the electronic structure and local coordination environment of the transition metals (TMs) are monitored in-operando with limited radiation damage. Compared to the conventional step-mode X-ray absorption spectroscopy, the QXAS can provide more reliable oxidation state change and more detailed local structure evolutions surrounding TMs (Ni and Co) in Ni-rich layered oxides. By leveraging these advantages of QXAS, we demonstrated that the Ni dominates the electrochemical process with the Co being almost electrochemically inactive. Reversible Ni ions movement between TMs sites and Li sites is also revealed by the time-resolved QXAS technique.

Hydrogeochemical processes, mobilization controls, soil-water-plant-rock fractionation and origin of fluoride around a hot spring affected tropical monsoonal belt of eastern Odisha, India

Fluorosis, poor crop yield, and degraded soil fertility due to excess fluoride are mostly associated with igneous exposures and fertilizer use. Geochemical, petrographic, microprobe and mineralogical examinations revealed thermal spring origin of fluoride (up to 15.8 mg L−1) affecting agriculture and public health in eastern India. No fluoride was detected in plant leaves and exposed charnockite, but nearby soils and siderite precipitates are enriched in fluoride up to 3.4 g kg−1. Both geogenic hot spring and fertilizer origin are proposed with fluorosis severity found to be closer to the hot spring where the stream, pond, and well enrichments might have resulted upon mixing with high F− hot spring water. The pond, stream, bore well, hand pump, well and hot spring water in the region are mostly fresh water (dissolved solids <1000 mg L−1) and hard to very hard in nature with a pH of 5.7–9.7 and a temperature of 23–55 °C. Major water is of NaCl type with minor components of mixed CaMgCl, CaHCO3 and CaCl types enriched in the order Na+>Ca2+≈Mg2+>K+>Si4+>FeT > Al3+ and Cl−> HCO3− > NO3− > SO42−> PO43−. Stream, pond, and bore well waters exhibit better suitability for irrigation use compared to hot spring and well waters, while all the studied water resources are of poor to unsuitable quality for human consumption. Carbonate weathering dominated silicate weathering processes for the stream, pond, and bore well water, while the latter was for hot spring and well water. Reverse ion exchange is the major process that prevailed in the region where rock-water interaction and evaporation governed the regional hydrochemistry. Fluoride mobilization is favored under alkaline conditions and enhanced by competitive anions in the order NO3− > SO42−> PO43−. Acidic rainwater does not favor fluoride release from soil, and F-containing siderite is prone to release fluoride under ambient conditions.

Graphene-polymer nanocomposites electrode with ionic nanofibrous membrane for highly sensitive supercapacitive pressure sensor

Wearable pressure sensors have obtained significant interests owing to their diverse applications in electronic skins and smart health informatics. Ultrahigh sensitivity, wide linearity, and better pressure resolution are highly desirable attributes of the pressure sensors for versatile applications. Here, a flexible supercapacitive pressure sensor (SPS) based on a novel reversible ion pumping mechanism is reported that remarkably increases the pressure sensitivity over a broad linear range exceeding the limits of the existing iontronic pressure sensors. The SPS is composed of lower concentration ionic nanofibrous membrane between two graphene-polymer nanocomposite electrolyte films, which engages in ion pumping, triggering a high electrical double layer capacitance under external stimuli. The fabricated SPS exhibited an ultra-high sensitivity of 9029 kPa−1 over wide linear range (0–100 kPa) with outstanding pressure resolution of 0.446%. Additionally, a wireless fitness tracker system is successfully demonstrated by integrating the SPS, which can monitor the food consumption and posture of users to improve their lifestyle.

Solvent control of the nucleation-induced voltage hysteresis in Li-rich LiFePO4 materials

Phase transformations during the reversible ion insertion into metal-ion battery materials have been extensively studied due to the importance of understanding the mechanisms of (de)lithiation and controlling the battery performance. In this work, we demonstrate that the electrolyte, which is typically neglected in the studies of phase transformation mechanisms, plays an essential role in governing the kinetics of nucleation. We compare nucleation rates for Li-rich LiFePO4 materials in carbonate and aqueous electrolytes and show that the nucleation rate is an order of magnitude higher in aqueous electrolyte. Consequently, this leads to a decrease in the hysteresis of the charge and discharge curves in an aqueous medium by 30%, i.e., a significant increase in the energy efficiency of cells with an aqueous electrolyte. We provide a detailed characterization of the lithium-ion intercalation kinetics and formulate assumptions about the possible reasons for the solvent dependence of the nucleation kinetics.

Vanadium Oxide-Poly(3,4-ethylenedioxythiophene) Nanocomposite as High-Performance Cathode for Aqueous Zn-Ion Batteries: The Structural and Electrochemical Characterization

In this work the nanocomposite of vanadium oxide with conducting polymer poly(3,4-ethylenedioxythiophene) (VO@PEDOT) was obtained by microwave-assisted hydrothermal synthesis. The detailed study of its structural and electrochemical properties as cathode of aqueous zinc-ion battery was performed by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The initial VO@PEDOT composite has layered nanosheets structure with thickness of about 30-80 nm, which are assembled into wavy agglomerated thicker layers of up to 0.3-0.6 μm. The phase composition of the samples was determined by XRD analysis which confirmed lamellar structure of vanadium oxide V10O24∙12H2O with interlayer distance of about 13.6 Å. The VO@PEDOT composite demonstrates excellent electrochemical performance, reaching specific capacities of up to 390 mA∙h∙g-1 at 0.3 A∙g-1. Moreover, the electrodes retain specific capacity of 100 mA∙h∙g-1 at a high current density of 20 A∙g-1. The phase transformations of VO@PEDOT electrodes during the cycling were studied at different degrees of charge/discharge by using ex situ XRD measurements. The results of ex situ XRD allow us to conclude that the reversible zinc ion intercalation occurs in stable zinc pyrovanadate structures formed during discharge.

Mitigating reverse emission in electroaerodynamic thrusters

Electroaerodynamic (EAD) thrusters have the potential to become a quieter and solid-state alternative to propellers in unmanned aircraft. An EAD thruster produces ions from atmospheric air and accelerates them across an electric field between two electrodes: an emitter, where ions are produced; and a collector, where they are neutralized. As ions drift from the emitter to the collector, they collide with neutral air molecules and transfer momentum to them, resulting in an ionic wind and a thrust force. Reverse emission from the collector is a major non-ideal effect in EAD systems that can reduce the efficiency of EAD thrusters: it increases the power draw of the device and eventually leads to electrical breakdown and sparking. Here, we perform a parametric study with a wire-to-cylinder electrode geometry using positive and negative corona discharges as well as wire-to-wire dielectric barrier discharges as ion sources. We show that reverse ion emission is primarily caused by a gas discharge at the tips of the cylindrical collectors, which increases current without contributing to thrust and produces audible noise. We identify three ways to mitigate reverse emission: increasing the collector diameter, increasing the collector span with respect to the emitter span, and attaching hemispherical end caps to the collector. By mitigating reverse emission, we show that the power draw of an EAD thruster can be significantly reduced (by up to 64% in our particular configuration) while still delivering the same thrust.

NOM fractionation by HPSEC-DAD-OCD for predicting trihalomethane disinfection by-product formation potential in full-scale drinking water treatment plants

Chlorination is a common method for water disinfection; however, it leads to the formation of disinfection by-products (DBPs), which are undesirable toxic pollutants. To prevent their formation, it is crucial to understand the reactivity of natural organic matter (NOM), which is considered a dominant precursor of DBPs. We propose a novel size exclusion chromatography (SEC) approach to evaluate NOM reactivity and the formation potential of total trihalomethanes-formation potentials (tTHMs-FP) and four regulated species (i.e. CHCl3, CHBrCl2, CHBr2Cl, and CHBr3). This method combines enhanced SEC separation with two analytical columns working in tandem and quantification of apparent molecular weight (AMW) NOM fractions using C content (organic carbon detector, OCD), 254-nm spectroscopic (diode-array detector, DAD) measurements, and spectral slopes at low (S206–240) and high (S350–380) wavelengths. Links between THMs-FP and NOM fractions from high performance size exclusion chromatography HPSEC-DAD-OCD were investigated using statistical modelling with multiple linear regressions for samples taken alongside conventional full-scale as well as full- and pilot-scale electrodialysis reversal and bench-scale ion exchange resins. The proposed models revealed promising correlations between the AMW NOM fractions and the THMs-FP. Methodological changes increased fractionated signal correlations relative to bulk regressions, especially in the proposed HPSEC-DAD-OCD method. Furthermore, spectroscopic models based on fractionated signals are presented, providing a promising approach to predict THMs-FP simultaneously considering the effect of the dominant THMs precursors, NOM and Br−.

High-performance dual carbon Li-ion hybrid capacitor constructed from N, S - co-doped candle soot derived carbon nanoparticles anode and porous carbon cathode

Lithium-ion capacitors (LICs) are one of the emerging and fast-growing energy storage devices due to their combination of high power/energy characteristics with long cyclic life. However, the kinetic imbalance between anode and cathode is a major hurdle in achieving high-performance LICs. In this work, we propose a dual carbon LIC device using a candle soot pollutant as the single source for the first time to derive a novel N, S-co-doped fractal-like carbon nanoparticles (NS-CSC) as anode and an activated co-doped porous carbon (NS-ACSC) as a cathode. The NS-CSC anode and NS-ACSC cathode half-cell demonstrate an outstanding reversible ion storage capacity of 2258 mAh g−1 and 125 mAh g−1 at 50 mA g−1, respectively. Benefitting from the doped carbon electrodes, the mass ratio optimized dual carbon NS-CSC//NS-ACSC (1:2) LIC device achieves high specific energy of 101.7 Wh kg−1 at 113 W kg−1, retaining a capacity of 81 % after 7000 cycles at 2 A g−1. Moreover, the fabricated LIC device powers a red light-emitting diode for a continuous 15 min, indicating its potential use in practical applications. This work emphasizes that the candle soot pollutant-derived carbon nanoparticles have the potential for use as an electrode in advanced energy storage devices.

(Invited) Switching Molecular Ionic Magnetism

Magneto-ionics of molecular based magnets, the ionic control of magnetism, promise ultralow-power sensor technologies, while the extent of reversible ion intercalation in turn is also the key state-of-charge feature in rechargeable battery electrodes. Here we report the reversible ion intercalation in molecular magnetic electrode, which simultaneously monitors the state of charge in battery and enables dynamic switching of its room-temperature magnetic transition. Microwave excited spin wave reveals lithiation degree in molecular-magnetic anode, enabling magneto-ionics towards the real-time monitoring of state of charge in rechargeable battery under a low magnetic field and radiofrequency. The structural vacancy and hydrogen-bonding networks in such molecular magneto-ionic compound enables the reversible lithiation and delithiation, which in turn, leads to a dynamical and reversible magnetization tunability.

Efficiency of Reverse Osmosis and Ion Exchange in Water Purification from Nitrates

Efficiency of Reverse Osmosis and Ion Exchange in Water Purification from Nitrates

Study on the Hydrogeochemical Processes Regulating the Groundwater Chemistry in the Southeast Rajasthan

ABSTRACT The current study is focused on evaluation of hydrogeochemical aspects of groundwater for analysis of groundwater chemistry and quality assessment in the south east Rajasthan (India). A total of 50 groundwater samples were collected and analyzed for the assessment of major cations and anions, total dissolved solid (TDS), electrical conductance (EC), total hardness (TH) and total alkalinity (TA), and the results were compared with the WHO standards of drinking water. The results have demonstrated that the groundwater is alkaline in nature and in most of the groundwater samples the quantity of TH, TDS, EC, TA and NO3- is exceeded to the WHO standards. Additionally, alkali metal ions are mainly contributed from the dissolution of halite and silicate weathering processes, whereas the alkaline earth metal ions from the carbonate dissolution and silicate weathering processes. The saturation indices (SI) values show that the groundwater in the study area is oversaturated in terms of dolomite, calcite and argonite while undersaturated in gypsum. Hydrogeochemically the groundwater is Ca.Mg-HCO3, Ca.Mg-Cl and Ca.Mg-SO4 types. Moreover, it is mixed type with reference to cations and anions. The ionic plots, molar ionic ratios, CAI, SI and Gibb’s diagram have revealed that the chemical weathering of rock minerals, reverse ion exchange and anthropogenic activities are the key processes, regulating the chemical composition of ground water in the study area.

Evaluation of groundwater quality for agricultural under different conditions using water quality indices, partial least squares regression models, and GIS approaches

Evaluating grouLindwater quality and associated hydrochemical properties is critical to manage groundwater resources in arid and semiarid environments. The current study examined groundwater quality and appropriateness for agriculture in the alluvial aquifer of Makkah Al-Mukarramah Province, Saudi Arabia, utilizing several irrigation water quality indices (IWQIs) such as irrigation water quality index (IWQI), total dissolved solids (TDS), sodium adsorption ratio (SAR), potential salinity (PS), magnesium hazard (MH), and residual sodium carbonate (RSC) assisted by multivariate modeling and GIS tools. One hundred fourteen groundwater wells were evaluated utilizing several physicochemical parameters, which indicating that the primary cation and anion concentrations were as follows: Na+ > Ca2+ > Mg2+ > K+, and Cl− > SO42˗ > HCO3˗ > NO3˗ > CO32˗, respectively, reflecting Ca–HCO3, Na–Cl, and mixed Ca–Mg–Cl–SO4 water facies under the stress of evaporation, saltwater intrusion, and reverse ion exchange processes. The IWQI, TDS, SAR, PS, MH, and RSC across two studied regions had mean values of 64.86, 2028.53, 4.98, 26.18, 38.70, and − 14.77, respectively. For example, the computed IWQI model indicated that approximately 31% of samples fell into the no restriction range, implying that salinity tolerance crops should be avoided, while approximately 33% of samples fell into the low to moderate restriction range, and approximately 36% of samples fell into the high to severe restriction range for irrigation, implying that moderate to high salt sensitivity crops should be irrigated in loose soil with no compacted layers. The partial least squares regression model (PLSR) produced a more accurate assessment of six IWQIs based on values of R2 and slope. In Val. datasets, the PLSR model generated strong estimates for six IWQIs with R2 varied from 0.72 to 1.00. There was a good slope value of the linear relationship between measured and predicted for each parameter and the highest slope value (1.00) was shown with RSC. In the PLSR models of six IWQIs, there were no overfitting or underfitting between the measuring, calibrating, and validating datasets. In conclusion, the combination of physicochemical characteristics, WQIs, PLSR, and GIS tools to assess groundwater suitability for irrigation and their regulating variables is beneficial and provides a clear picture of water quality.

Hydrogeochemical characterization of groundwater and their associated potential health risks.

The present study assessed the human health risk exposure from the consumption of poor quality groundwater in the Lucknow area, a part of Central Ganga alluvial plain in India. Around 27 (n = 27) groundwater samples were collected from the study area. The analytical results of the samples (n = 27) collected indicate silicate and carbonate weathering is the dominant process along with cation exchange, sulfide oxidation, and reverse ion exchange. The type of groundwater is Ca2-Na-HCO3- type having all cations and anions within permissible WHO limits except for iron (Fe2+) and nitrate (NO3-). The high concentrations of Fe2 and NO3- in samples indicate the possibility of a non-geogenic point source for the same in an urban-influenced environment. The ionic concentration of dissolved constituents is used in weighted overlay analysis to generate the water quality index (WQI). WQI indicates that most urban areas (~ 98.52%) have fallen in the good to excellent category except few situated in the highly populated parts of Lucknow. The ionic concentrations of Fe2+ and NO3- have been further used to estimate human health risk by integrating regional urban population density data in Lucknow. The risk map shows alarming risks in the west-central part, where nearly ~ 35% of the total area is at moderate to high health risk.

Calorimetry can detect the early onset of hydrolysis in hybrid supercapacitors with aqueous electrolytes

This study investigates the effect of cation species on the onset of electrolyte hydrolysis in hybrid supercapacitors with aqueous electrolytes using isothermal operando calorimetry. The cells consisted of a positive α-MnO2 cryptomelane electrode and a negative activated carbon (AC) electrode with either 0.5 M K2SO4 or 0.5 M Cs2SO4 aqueous electrolytes. They were characterized using cyclic voltammetry and galvanostatic cycling. In addition, the instantaneous heat generation rate at each electrode was measured using a custom isothermal operando calorimeter. Heat generation associated with resistive losses (Joule heating) and reversible ion adsorption/desorption was clearly identified. For larger potential windows, an endothermic dip, attributed to the onset of hydrolysis, was observed at the positive α-MnO2 electrode where K+ and Cs+ ions engaged in fast surface redox reactions. Interestingly, this endothermic dip appeared at 1.8 V and 2.0 V for K2SO4 and Cs2SO4 aqueous electrolytes, respectively. The difference in the stable operating potential window was attributed to thinner solvation shell around Cs+ cation than for K+ thus reducing the amount of water present near the electrodes as ions partially shed their solvation shells during adsorption. The early onset of hydrolysis could be observed by isothermal operando calorimetry before it could be observed with conventional electrochemical methods.

Expansion of the Inguinal Adipose Tissue Depot Correlates With Systemic Insulin Resistance in C57BL/6J Mice.

To accommodate surplus energy, the adipose tissue expands by increasing adipocyte size (hypertrophy) and number (hyperplasia). The presence of hypertrophic adipocytes is a key characteristic of adipose tissue dysfunction. High-fat diet (HFD) fed C57BL/6J mice are a commonly used model to study obesity and obesity-related complications. In the present study, we have characterized adipose plasticity, at both the cellular and tissue level, by examining the temporal development of systemic insulin resistance and adiposity in response to HFD-feeding for 4, 8, and 12 weeks (4w, 8w, and 12w). Within the same time frame, we examined systemic metabolic flexibility and adipose plasticity when switching from HFD- to chow-diet during the last 2 weeks of diet intervention (referred to as the reverse (REV) group: 4wREV (2w HFD+2w chow), 8wREV (6w HFD+2w chow), 12wREV (10w HFD+2w chow)). In response to HFD-feeding over time, the 12w group had impaired systemic insulin sensitivity compared to both the 4w and 8w groups, accompanied by an increase in hypertrophic inguinal adipocytes and liver triglycerides. After reversing from HFD- to chow-feeding, most parameters were completely restored to chow control levels for 4wREV and 8wREV groups. In contrast, the 12wREV group had a significantly increased number of hypertrophic adipocytes, liver triglycerides accumulation, and impaired systemic insulin sensitivity compared to chow-fed mice. Further, image analysis at the single-cell level revealed a cell-size dependent organization of actin filaments for all feeding conditions. Indeed, the impaired adipocyte size plasticity in the 12wREV group was accompanied by increased actin filamentation and reduced insulin-stimulated glucose uptake compared with chow-fed mice. In summary, these results demonstrate that the C57BL/6J HFD-feeding model has a large capacity to restore adipocyte cell size and systemic insulin sensitivity, and that a metabolic tipping point occurs between 8 and 12w of HFD-feeding where this plasticity deteriorates. We believe these findings provide substantial understanding of C57BL/6J mice as an obesity model, and that an increased pool of hypertrophic ING adipocytes could contribute to aggravated insulin resistance.

Groundwater quality and its suitability for drinking and irrigational purpose in Bhojpur district: middle Gangetic plain of Bihar, India

Abstract A total of 138, samples have been collected in both pre and post monsoon season to understand the seasonal variability in groundwater quality and its suitability for drinking and domestic water supply. The samples were analysed for physical parameters, major ions along with fluoride and uranium. The results were integrated with GIS to represent both seasonal and spatial variations of groundwater quality parameters, drinking groundwater quality index (DGQI) and irrigation groundwater quality index (IGQI). Results show that groundwater is alkaline in nature and largely controlled by the silicate weathering, ion exchange and reverse ion exchange processes. However high nitrate concentration exceeding the WHO guideline suggests the influence of anthropogenic activities on groundwater quality. The average values of the major ions concentrations was found higher in pre monsoon season due to change in the recharge. The DGQI values of 6 samples in pre monsoon and 2 samples in post monsoon season falls under poor water quality. However, individual irrigation indices along with the combine IGQI indicate groundwater is suitable for irrigation in both the seasons. These results along with the seasonal and spatial variability map may help the decision makers in planning for better domestic and irrigation water supply.

Gelation, clustering, and crowding in the electrical double layer of ionic liquids.

Understanding the bulk and interfacial properties of super-concentrated electrolytes, such as ionic liquids (ILs), has attracted significant attention lately for their promising applications in supercapacitors and batteries. Recently, McEldrew et al. [J. Phys. Chem. B 125, 2677 (2021)] developed a theory for reversible ion associations in bulk ILs, which accounted for the formation of all possible (Cayley tree) clusters and a percolating ionic network (gel). Here, we adopt and develop this approach to understand the associations of ILs in the electrical double layer at electrified interfaces. With increasing charge of the electrode, the theory predicts a transition from a regime dominated by a gelled or clustered state to a crowding regime dominated by free ions. This transition from gelation to crowding is conceptually similar to the overscreening to crowding transition.

Ultrasound-promoted preparation of polyvinyl ferrocene-based electrodes for selective formate separation: Experimental design and optimization

The selective separation of ions is a major technological challenge having far-ranging impacts from product separation in electrochemical production of base chemicals from CO2 to water purification. In recent years, ion-selective electrochemical systems leveraging redox-materials emerged as an attractive platform based on their reversibility and remarkable ion selectivity. In the present study, we present an ultrasound-intensified fabrication process for polyvinyl ferrocene (PVF)–functionalized electrodes in a carbon nanotube (CNT) matrix for selective electro-adsorption of formate ions. To this end, a response surface methodology involving the Box–Behnken design with three effective independent variables, namely, PVF to CNT ratio, sonication duration, and ultrasonic amplitude was applied to reach the maximum formate adsorption efficiency. The fabricated electrodes were characterized using cyclic voltammetry, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). SEM images revealed that an optimized ultrasonic amplitude and sonication time provided remarkable improvements in electrode morphology. Through a sedimentation study, we qualitatively demonstrate that the main optimized conditions improved PVF/CNT dispersion stability, consequently providing the highest number of active surface sites for adsorption and the highest adsorption efficiency. The highest percentage of active electrode surface sites and the maximum adsorption efficiency were 97.8 and 90.7% respectively at a PVF/CNT ratio of 3, ultrasonication time of one hour, and 50% ultrasonic amplitude.