Dilute HCl Solution Research Articles

Convenient determination of polystyrene microplastics in soils by gel permeation chromatography-ultraviolet detection analysis

Microplastics (MPs), especially polystyrene microplastics (PS-MPs), have emerged a new worldwide pollutant, prompting significant public concern regarding their detection in environmental media. Analysis of PS-MPs in soil remains as a challenging task for analysts due to the highly intricate matrices. This work presents a practical approach for detecting PS-MPs in soil, which involves dilute HCl-assisted extraction and gel permeation chromatography- ultraviolet detection (GPC-UV) analysis. The presence of MPs in soil was confirmed through the use of a scanning electron microscope in conjunction with energy dispersive spectroscopy investigation. PS-MPs was isolated from soil, by agitating it with a diluted HCl solution, filtering the resulting liquid, and dissolving the residue on the filter with THF. The extractant was subsequently determined by GPC-UV. The introduction of a small amount of HCl into the extraction system was found to greatly expedite the settling of soil in water and enhance the efficacy of extracting PS-MPs in about 30 min. The linear range of PS-MPs was from 1.0 to 100 μg/mL with R2 > 0.999. Good reproducibility was obtained with the intra-day relative standard deviation (RSD, n = 3) of 1.36 % and the inter-day RSD (n = 3) of 4.78 %. The concentration of PS-MPs in soil samples were N.D. - 2.33 μg/g, and the good recoveries were 76.7–100.3 %. The corresponding AFGEEprer score was calculated to be 0.59, indicating the concept of green analytical chemistry for the pretreatment method. These results indicated that this method has a powerful potential for the accurate and rapid determination of PS-MPs in soil.

Liquidizing crystal MIL-100(Fe) to coating silica powder for purifying wastewater

Although MIL-100(Fe) was regarded as an ideal material for the environmental remediation, it could not be applied in practical because of the potential eco-environmental risk and cost. In this work, a novelty strategy of liquidizing crystal MIL-100(Fe) was posted for the first time through inhibiting the crystallization process and forming physical MIL-100(Fe) gel. Due to this MIL-100(Fe) sol–gel, MIL-100(Fe) could easy cover on the surface of silica powder (SiO2) through simple soaking operation. MIL-100(Fe) covering on SiO2 (MIL-100(Fe)@SiO2) could be quickly separated from wastewater spontaneously owing to the carrier of SiO2, even in a tank of 2.0 m, which made it possible for purifying wastewater in practical. MIL-100(Fe)@SiO2 could remove phosphate with a removing ratio of closing 100 % at an initial concentration of 10 mg/L, while more than 95 % towards methyl orange (MO). The removing ratio of MO by MIL-100(Fe)@SiO2 did not obviously decrease when the concentration of MO increased to 100 mg/L. And the adsorption performance of phosphate did not affect by pH among 3.0–9.0. The adsorption amount exceeded 50 % of maximum adsorption capacity for phosphate within 30 min, while 90 % for MO. Monodentate mononuclear coordination could explain the adsorption of phosphate by MIL-100(Fe)@SiO2. The N atom in MO might be acted as Lewis acid to coordinate with MIL-100(Fe)@SiO2. After adsorption, the P-saturated and MO-saturated MIL-100(Fe)@SiO2 could be effectively regenerated by the dilute HCl and NaOH solution, respectively. The recovery ratio of adsorption capacity for phosphate and MO were up to 97.7 % and 71.6 %.

Two-step recovery of Pb(II) and Cd(II) with thiophene functionalized hydrogel from lead-acid battery wastewater: Insight into pH-regulated separation

Lead-acid batteries (LAB) are one of the most harmful batteries to the environment and human health. LAB wastewater contains Pb(II) and Cd(II), meanwhile, strongly acidic media (pH ≤ 3.0) poses a serious threat to ecological safety and human health. Herein, a novel thiophene functionalized biomass-based hydrogel (PEITC-SA) containing various groups was prepared by a two-step synthesis strategy involving liquid-phase modification and dopant-induced crosslinking. The static experiments relating to selectivity, kinetics and equilibria confirmed that PEITC-SA not only had a high adsorption capacity and selectivity for Pb(II) at pH 2.0, but also had a good adaptability for both Pb(II) and Cd(II) at pH 3.0. Moreover, the coexistence of inorganic salts and organic compounds had little effect on the adsorption of Pb(II) and Cd(II). Complexation was confirmed as the main adsorption force at pH 2.0, meanwhile at pH 3.0, electrostatic interaction, ion exchange interaction and complexation were all involved. According to Density Functional Theory calculations, tetradentate coordination of thiophene and amino groups was the most stable. Dynamic column experiments towards simulated LAB wastewater demonstrated the high efficiency and feasibility of pH-regulated fractional treatment, which of unexpected economic prospects. Furthermore, PEITC-SA could be easily desorbed with dilute HCl solution. Therefore, PEITC-SA possessed satisfactory potential for the resource recovery towards LAB wastewater through pH-regulated two-step separation.

Comparing the Efficacy of Select Natural and Synthetic Corrosion Inhibitors on Copper and Iron

Six corrosion inhibitors were evaluated for their effectiveness at preventing corrosion on copper and mild steel in a short-term experiment lasting two weeks. Half of the inhibitors tested were alcohol extracts of natural products (ginger, garlic, and black pepper), and the others were standard chemical reagents including benzotriazole (BTA), cysteine, and 5-amino-1,3,4-thiadiazole-2-thiol (AMT). Metal coupons of both mild steel and copper were immersed in a 0.007M dilute HCl solution with one of the six inhibitors or a combination of two inhibitors. The pH of each solution was monitored to track the corrosion rate and this method proved to be remarkably sensitive and nuanced, allowing for the subtleties of the decay mechanisms to be determined.

Fabrication of thin silicon flakes through dealloying from laser directed energy deposition Ca-Si alloys

Abstract In this study, thin silicon flakes were fabricated through dealloying from laser directed energy deposition (LDED) Ca-Si alloys, and the solidification mechanism of the lamellar eutectic microstructure was studied. With 1200 W laser power and 450 mm/min scanning speed, the LDED Ca-Si alloys have a fine lamellar eutectic microstructure and are easily separated from copper substrates. After dealloying in the diluted HCl solution for 6 h, the thin silicon flakes ranging in thickness from 100 nm to 0.5 μm were obtained. The formation of the thin flakes was attributed to fine lamellar Si phases in precursor alloys. The rapid solidification of laser processing could refine the microstructure, especially Si phases, and improve the chemical homogeneity of the material. Combining laser processing and dealloying, a cost-effective and scalable strategy was devised to fabricate fine powder from a laser processing optimized microstructure.

Co-utilization of electric arc furnace dust and copper slag for preparing zinc ferrite based on microwave roasting

The feasibility of preparing zinc ferrite from high-zinc electric arc furnace (EAF) dust and high-iron copper slag (CS) based on direct microwave roasting of the wastes together was assessed in this study, with a focus on the effect of microwave roasting temperature. According to the permittivity and permeability measurements of the raw materials, in conjunction with thermodynamic and experimental analyses, it was found that increasing temperature facilitated the formation of zinc ferrite. By fixing the Fe/Zn molar ratio of 2.0 and roasting time of 30 min, elevating the temperature from 500 ºC to 700 ºC led to a significant increase of the percentage of acid-insoluble zinc in the form of zinc ferrite from 81.48% to 94.93%. Further increase of the temperature to 900 °C could not evidently promote the formation of zinc ferrite. After removing impurities by dilute HCl solution and nano milling, the zinc ferrite product had a single phase with the purity of 99.9 wt%. It can act as a great adsorbent of heavy metal ions due to its superior adsorption capacities of 87.99 mg/g, 86.51 mg/g, 86.22 mg/g, and 90.32 mg/g for Pb(II), Cr(VI), Cd(II), and Hg(II), respectively, and as a catalyst for removing tetracycline (TC) using peroxymonosulfate (PMS) with the removal efficiency of 78.54% after 40 min under visible light irradiation. This study offers a facile method for co-utilization of EAF dust and CS to produce value-added functional materials.

Benzimidazole-modified chitosan as a controller for the destruction of Al and H2 generation in the acidic environment

Benzimidazole-modified chitosan (CS-BISP) was utilized as an effective mitigator controlling the destruction of Al, and the generation of H2 in dilute HCl solutions. The techniques of gasometry, mass loss, potentiometry, galvanostatic polarization, GP, and electrochemical impedance spectroscopy, EIS, were involved. The rate of the produced H2 is found to depend on the concentration of the CS-BISP and the temperature. EIS data indicated that the existence of CS-BISP in the HCl solution increases the charge transfer resistance, Rct, and reduces the double-layer capacitance, Cdl, confirming the presence of an insulating film on the metal surface via an adsorption mechanism. GP data explained that the CS-BISP behaves as an effective inhibitor of a mixed kind. The protection efficiency was raised with increasing the CS-BISP concentration and is lowered by temperature. The protection efficiency reaches 94.2% at 300 mg L−1, at 25 °C. The free energy of adsorption, ΔGoads, varied between – 26.13 and −26.88 kJ/mol depending on the solution temperature which emphasizes the presence of physical and chemical adsorption mechanisms. The negative sign of ΔGoads proved a spontaneous adsorption process with the stability of the adsorbed film. The reduction in the Kads value with temperature signifies the desorption of a few of the CS-BISP polymeric molecules from the surface of the Al electrode. The CS-BISP molecule was theoretically examined utilizing density functional theory and Monte Carlo simulations. The theoretical parameters coincide with the experimental results.

Waste bamboo‐derived biochar and multiporous carbon as adsorbents for methyl orange removal

AbstractMaterialsMultiporous carbon (MPC) with a high specific surface area (1121 m2g−1) and mesoporous and microporous structures was prepared by using bamboo biochar (308 m2g−1) as raw material.MethodsThe preparation involved a CaCO3 activation process, where CaCO3 served as both the template for mesopores and the activating agent for micropores. The template could be easily removed by dilute HCl(aq) solution, making the preparation process simpler and more environmentally friendly compared to using mesoporous SiO2 as a hard template.ResultsThe performance of the MPC and biochar as adsorbents for methyl orange (MO) dye was investigated by means of thermal dynamic isotherms and kinetic models tests. The Langmuir isothermal analysis results revealed that the MPC exhibited a significantly higher MO adsorption capacity (344.8 mg g−1) compared to the bamboo biochar (12.4 mg g−1). The adsorption kinetics of the MPC followed a pseudo‐second‐order model.ConclusionOverall, the obtained MPC material offers a cost‐effective, environmentally friendly, and efficient solution for removing dyes from aqueous solutions.

Batch and dynamic acid regeneration evaluation of granular activated carbons used in water cleaning treatment system. A comparative study between advanced analytical methods and a new infra-red thermographic method

A new Infrared Thermography (IRT) technique was used for textural characterization of different granular activated carbons (GAC) samples. Virgin GAC was used in a water cleaning system. Upon GAC exhaustion, an HCl and HNO3 acid regeneration method was explored using different concentration and contact time. Thermographic parameters for evaluation were (1) average temperature of the sample and (2) surface thermal density which were both deduced after applying digital images processing from the obtained IRT thermograms by flooding water over the GAC sample. Linear correlations were found between IRT parameters with SBET and Vmic (obtained from N2 gas adsorption) for exhausted and regenerated samples, being for the temperature, 0.94 and 0.91 respectively and for the surface thermal density, 0.93 and 0.92 respectively. IRT measurement results have been correlated and assessed with TGA, XRF, gas adsorption (N2 at 77 K and CO2 at 273 K), SEM-EDX NMR, FTIR, TD-GC-MS, GC-MS, GAC stability and elemental analysis. Based on all these techniques, it was found that mainly metal ions were adsorbed on the GAC. Chemical regeneration using a 7.4 wt% HCl solution was the most successful approach in removing the adsorbed metal ions (Ca, Mn and Ba) in comparison with more diluted HCl solution and HNO3 solutions. Dynamic regeneration also demonstrated that HCl performs better with a breakthrough time of 249 min, much lower than HNO3 (337 min). The used experimental column and the industrial water filter behave quite similar. Finally, in order to confirm the performance of the regenerated sample, isothermal adsorption studies as a function of the total water hardness were done, which confirmed that the regenerated GAC sample using 7.4 wt% HCl offers the best results (58.3% removal) in comparison with HNO3.

Enhanced Dissolution of Metal Oxides in Hydroxylated Solvents - Towards Application in Lithium-Ion Battery Leaching.

The recovery of critical metals from spent lithium-ion batteries (LIBs) is rapidly growing. Current methods are energy-intensive and hazardous, while alternative solvent-based strategies require more studies on their 'green' character, metal dissolution mechanism and industrial applicability. Herein, we bridged this gap by studying the effect of dilute HCl solutions in hydroxylated solvents to dissolve Co, Ni and Mn oxides. Ethylene glycol emerged consistently as the most effective solvent, dissolving up to four times more Co and Ni oxides than using aqueous acidic media, attributed to improved chloro-complex formation and solvent effects. These effects had a significant contribution compared to acid type and concentration. The highest Co dissolution (0.27 M) was achieved in 0.5 M HCl in 25 % (v/v) glycerol in water, using less acid and a significant amount of water compared to other solvent systems, as well as mild temperatures (40 °C). This solvent was applied to dissolve battery cathode material, achieving 100 % dissolution of Co and Mn and 94 % dissolution of Ni, following what was concluded to be a mixed mechanism. These results offer a simple alternative to current leaching processes, reducing acid consumption, enhancing atomic efficiency, and paving the way for optimized industrial hydrometallurgical processes leaning to 'greener' strategies.

Microwave‐Assisted Fabrication of Superamphiphobic Surfaces on Aluminum Substrates

The field of superamphiphobic surface fabrication has evolved rapidly in the last decade; however, research on important issues such as sustainability and green chemistry procedures is still scarce. Herein, a simple method of microwave irradiation (MW) to minimize energy consumption during the preparation of superamphiphobic aluminum (Al) surfaces is reported. Al substrates are first etched in diluted HCl solutions to generate a microstructure and then irradiated in a commercial microwave unit for several time intervals, temperatures, and pressures. The surfaces are then coated with different compounds, and the wettability is tested with high and very‐low surface tension liquids. Optical profilometry and scanning electron microscopy images show that the density of hierarchical micro‐nanostructures increases with MW time, temperature, and pressure. At 170 °C and 7.9 bar, the surfaces present a high density of structures and re‐entrant topographies. The obtained coatings display excellent repellence to liquids with surface tensions as low as 27.5 mN m−1. X‐ray photoelectron spectroscopy data show the importance of efficient surface functionalization for the production of superamphiphobicity in Al substrates. The results show that MW irradiation of Al substrates can be a green and efficient method for fabricating superamphiphobic surfaces.

Ballistic transport and surface scattering in (In,Ga)As-InP heterostructure narrow channels

Narrow conduction channels are fabricated from an In0.75Ga0.25As-InP heterostructure using electron-beam lithography and dry etching. The etched surface is realized to be smooth by employing a reactive ion etching. The etching-induced surface conduction is eliminated by removing the damaged surface layer using a diluted HCl solution. The negligible surface depletion for the In-rich quantum well enables to create conducting channels in arbitrary geometries such as in a circular shape. We evidence the presence of a ballistic contribution in the electron transport by demonstrating a rectification of rf excitations that is achieved by the magnetic-field-tuned transmission asymmetry in the circularly-shaped channels. The absence of the surface depletion is shown to cause, on the other hand, a surface scattering for the electrons confined in the channels. An increase of the resistance, including its anomalous enhancement at low temperatures, is induced by the gas molecules attached to the sidewalls of the channels. We also report a large persistent photoconduction, which occurs as a parallel conduction in the undoped InP barrier layer.

Solvent extraction of Terbium(III) from chloride solution using organophosphorus extractant, its mixture and ionic liquid in the presence of organic acids

Addition of organic acids to dilute hydrochloric acid solution can improve the extraction of rare earth elements by single cationic extractants. However, the correlation between the chemical structure of organic acids and the extraction of REEs as well as the variation in equilibrium pH has not been elucidated. In this study, we investigated the extraction of Tb(III) from dilute HCl solutions containing an organic acid like formic, lactic, fumaric, or maleic acid. As extractants, single Cyanex 272, a mixture of Cyanex 272 and Alamine 336 (Ala336-Cy272), and an ionic liquid (ALi-Cy272) synthesized by Cyanex 272 and Aliquat 336 were used. The speciation of Tb(III) in dilute HCl solutions containing organic acids was analyzed. In extraction of Tb(III), organic acids showed two roles as complexing and buffering agent, which depended on the chemical structure of the acids. There was some difference in the extraction of Tb(III) between single Cyanex 272 and ionic liquid, ALi-Cy272. During extraction with ALi-Cy272, formic and lactic acid negatively affected the extraction of Tb(III). The fact that the chemical structure of organic acids affected the extraction of Tb(III) from dilute HCl solution by the studied extractants can provide important information on the selection of suitable extraction systems.

Low-cost superhydrophobic coating on aluminum alloy with self-cleaning and repellency to water-based mixed liquids for anti-corrosive applications

This work seeks to develop a low-cost superhydrophobic coating on 5052 aluminum alloy using a combination of methods. First, top-down with acid etching with dilute HCl solution for a few minutes. Second, bottom-up by simple deposition of layered double hydroxide (LDH) film; Third, chemical modification of the surface with stearic acid. Through the applied methodology, it is possible to obtain superhydrophobic coatings with a contact angle of 164° and sliding angles of 1°. The obtained coating also shows high repellency and low sliding angle value for different commercial liquid foods such as orange juice, grape juice, chocolate milk, iced tea, isotonic, and cola-based soda. The Tafel method reveals that corrosion inhibition efficiency is 97.7 % and 97.4 % after 24 h of exposure in 0.6 mol/L NaCl solution and cola-based soda medium (pH = 2,5), respectively. The immersion test for 21 days (3 weeks) in distilled water and NaCl solution (0.6 mol/L) shows a change of the wettability characteristic on the coated specimens to hydrophobic and hydrophilic at the end of the experiment, respectively. Future work intends to incorporate harder particles that can further improve the mechanical durability of the LDH-based superhydrophobic coating, aiming at the application as food contact materials.

Accelerated Photodegradation of Organic Pollutants over BiOBr/Protonated g-C3N4

Interfacial engineering has emerged as an effective strategy to optimize the photocatalytic activity of heterojunctions. Herein, the interface between graphitic carbon nitride (g-C3N4) and BiOBr was readily regulated by a protonation treatment. The synthesized BiOBr/g-C3N4 heterojunctions were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results show that pretreating g-C3N4 in diluted HCl solution led to a partial protonation of g-C3N4, which ensured intimate contact and high dispersion of supported BiOBr without changing the surface area, bulk g-C3N4 structure, or visible light absorption. The abundant BiOBr/g-C3N4 interfaces remarkably improved the separation and transfer of photogenerated carriers, which produced more h+ and O2●− to accelerate the photocatalytic degradation of organic pollutants. The photocatalytic activities of the BiOBr/g-C3N4 heterojunctions were evaluated by the degradation of RhB under visible-light irradiation (λ ≥ 420 nm). The apparent reaction (pseudo-first-order) rate constant of BiOBr supported on partially protonated g-C3N4 (Bpg-C3N4-0.75) is ca. 3-fold higher than that of BiOBr supported on pristine g-C3N4 (Bg-C3N4), verifying interfacial engineering as an effective strategy to optimize the catalytic activity of heterojunctions.

Removal of direct blue 71 and methylene blue from water by graphene oxide: effects of charge interaction and experimental parameters

Graphene oxide (GO) was synthesized by modified the Hummers method and used as an effective adsorbent for removing direct blue 71 (DB 71) and methylene blue (MB) from water. Surface characteristics of the produced GO materials and related physiochemical properties of the organic dyes were systematically examined to reveal removal mechanisms. Thermodynamics, kinetics, and regeneration of GO adsorbent were also studied to disclose the nature of the adsorption and the reusability of adsorbent. GO adsorbed the cationic MB better than the anionic DB 71 mainly due to the electrostatic attraction between negatively charged GO’s surface and the positively charged MB molecules. Langmuir isotherm better described MB and DB 71 adsorption than the Freundlich model. The adsorption capacities of GO of 476.19 mg/g (for MB) and 175.41 mg/g (for DB 71) were considerably higher than those of other adsorbents such as activated carbon, chitosan, and biochar. MB and DB 71 adsorption process was spontaneous, endothermic, and governed by both physisorption and chemisorption. GO could be regenerated by methanol and dilute HCl solutions, and reused as an efficient adsorbent. This study provides a comprehensive data on the MB and DB71 adsorption processes, and an efficient approach on the regeneration of GO adsorbent.

Determination of Ionic Diffusion Coefficients in Ion‐Exchange Membranes: Strong Electrolytes and Sulfates with Dissociation Equilibria

AbstractIonic diffusion coefficients in the membrane are needed for the modelling of ion transport in ion‐exchange membranes (IEMs) with the Nernst‐Planck equation. We have determined the ionic diffusion coefficients of Na+, OH−, H+, Cl−, SO42−, NaSO4−, and HSO4− from the diffusion experiments of dilute NaCl, NaOH, HCl, Na2SO4, and H2SO4 solutions through IEMs and the membrane conductivity measured in these solutions, using electrochemical impedance spectroscopy. The order of diffusion fluxes across the anion‐exchange membrane is found to be as H2SO4>HCl>NaCl>Na2SO4>NaOH, whereas for the cation‐exchange membrane it was NaOH>NaCl>Na2SO4≥H2SO4. Special attention is given to sulfates because of the partial dissociation of bisulfate and NaSO4−, which makes the use of the Nernst‐Hartley equation, that is, splitting the electrolyte diffusion coefficient into its ionic contributions, impossible. The expression of the diffusion coefficient of sulfates taking into account the dissociation equilibrium has been derived and the corresponding Fick equation has been integrated. In addition, for sulfates, finite element simulations with COMSOL Multiphysics, applying a homogeneous membrane model, were done to give estimates of their ionic diffusion coefficients. This work offers a convenient approach to finding diffusion coefficients of various ions inside IEMs.

Synthesis and characterization of MgCo2O4 nanoparticles: Application to removal of Ni2+ in aqueous solution by adsorption

The present study is based on the adsorption of Ni2+ in aqueous solution on the spinel MgCo2O4 synthesized by nitrate route, followed by calcination at 500 °C. The powder was characterized by X-ray diffraction (XRD), FTIR spectroscopy, SEM/EDX analysis and specific surface area. It crystallizes in a cubic symmetry (Space Group: Fd-3m) and the SEM image shows hexagonal-shaped grains with visible porosity. The effects of the initial Ni2+ concentration, catalyst dose, temperature and pH were investigated. The optimization was found for 0.5 g/ L, 25 mg/ L, pH ∼ 6 and 50 °C respectively with a maximum efficiency of 99%. The experimental data were analysed by different isotherms. The Langmuir model indicates a better representation with a high adsorption capacity of 140 mg/g and a correlation coefficient (R²) of 0.99, thus showing that MgCo2O4 is an efficient adsorbent for the Ni2+ recovery. The kinetic data are well fitted by the pseudo second-order model. The positive zeta potential leads to a high adsorption capacity. The thermodynamic parameters revealed that the Ni2+ adsorption on the spinel is endothermic (ΔH° = 27.236 kJ/ mol) and spontaneous (ΔG° = −2.045 kJ/ mol). The spinel is regenerated with diluted HCl solution without noticeable loss of adsorption quality after continuous cycles (adsorption / desorption).

Regulating surface-pore structure of PES UF membrane by addition of “active” nano-CaCO3

A small surface-pore ultrafiltration membrane with a high surface porosity was fabricated from a polyether sulfone (PES) dope solution containing a small quantity of CaCO3 nanoparticles (nano-CaCO3), which coagulated in dilute HCl solution. During membrane formation, CO2 nanobubbles were in-situ generated to delay phase inversion, which ameliorated the membrane structure and performance because CO2 nanobubbles are amphiphobic to water and solvent. With increasing nano-CaCO3 content (from 0 to 0.15%) in the dope solution, the surface porosity and the surface-pore density of the obtained PES UF membrane were markedly increased from 1.76 to 6.50% and from 8.31 × 1014 to 5.08 × 1015 m−2, respectively. Nonetheless, the surface-pore size decreased from 13.35 to 8.29 nm, and so as the distribution. The optimal membrane exhibited a high pure water flux (698.2 L·m−2·h−1) and a high rejection to bovine serum album (>99%) with a moderate anti-fouling ability. This work would be of great significance for precision separation in biopharmaceutical, food processing, and other related applications.

Assessing the influence of isotopic composition of water on that of clay minerals during chemical treatments

The isotopic composition of hydrogen in authigenic minerals is a useful tool to reconstruct past paleo-environments. Clay minerals are an important component of authigenic minerals in soils and sediments but they usually occur with other compounds that must be eliminated before the analysis, such as organic matter and carbonates. Thus, various “pre-treatments” are used, generally involving dilute HCl and H2O2 solutions in water. In this work, the influence of the isotopic composition of the water used in these pre-treatment solutions is assessed, using ten different samples of clay minerals. The isotopic composition of hydrogen was measured in each sample after HCl pre-treatment alone, H2O2 pre-treatment alone and both HCl and H2O2 pre-treatments in sequence, using two types of water in the pre-treatment solutions: one 2H-enriched and one 2H-depleted. The results indicate some influence of the isotopic composition of the water on the clay minerals after pre-treatment. In general, the samples showed significant alteration by HCl pre-treatment and negligible alteration by H2O2 pre-treatment. A pure kaolinite reference material did not show any change by chemical pre-treatment while a smectite reference material did show significant effects. Other samples (Ethiopian lacustrine sediment samples and Spanish cave sediments) showed important differences, which also depend on clay mineralogy. Thus, mineralogy seems to be the main cause of the variability in the alteration, especially the quantity of smectite. In addition, this result challenges the utility of clay minerals for isotope studies in acid conditions, such as in acidic soils, to reconstruct past environments and, therefore, climate changes.