HCl Aqueous Solution Research Articles

Revealing the Mechanisms of Metal Adsorption by Bauxite Residue

Acid treatment of bauxite residue (BR) has been one of the main approaches to enhance its metal adsorption performance. However, the acid treatment mechanisms remain poorly understood and is complicated by the variable and complex mineralogy of bauxite residue and different test conditions in previous studies. In this study, bauxite residue samples were treated with aqueous HCl solutions, with concentrations ranging from 0 to 0.25 M. The dissolution kinetics of the major elements (Na, Al, Ca, Fe, and Si) and target metals (Pb2+ and Cu2+) for ion exchange and adsorption performance were measured. The solid samples were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) cross-sectional elemental mapping to determine the reaction mechanisms. The results revealed that the adsorption performance decreased with increasing acid concentrations, which is related to the structural changes of the sodalite phase. Other mineral phases, such as hematite, boehmite, and quartz, play a minor role in the adsorption. Additionally, different adsorption mechanisms between Pb2+ and Cu2+ were revealed, which were related to surface disruption.

Electrodialysis with Bipolar Membranes for the Sustainable Production of Chemicals from Seawater Brines at Pilot Plant Scale.

Environmental concerns regarding the disposal of seawater reverse osmosis brines require the development of new valorization strategies. Electrodialysis with bipolar membrane (EDBM) technology enables the production of acid and base from a salty waste stream. In this study, an EDBM pilot plant with a membrane area of 19.2 m2 was tested. This total membrane area results much larger (i.e., more than 16 times larger) than those reported in the literature so far for the production of HCl and NaOH aqueous solutions, starting from NaCl brines. The pilot unit was tested both in continuous and discontinuous operation modes, at different current densities (200-500 A m-2). Particularly, three different process configurations were evaluated, namely, closed-loop, feed and bleed, and fed-batch. At lower applied current density (200 A m-2), the closed-loop had a lower specific energy consumption (SEC) (1.4 kWh kg-1) and a higher current efficiency (CE) (80%). When the current density was increased (300-500 A m-2), the feed and bleed mode was more appropriate due to its low values of SEC (1.9-2.6 kWh kg-1) as well as high values of specific production (SP) (0.82-1.3 ton year-1 m-2) and current efficiency (63-67%). These results showed the effect of various process configurations on the performance of the EDBM, thereby guiding the selection of the most suitable process configuration when varying the operating conditions and representing a first important step toward the implementation of this technology at industrial scale.

Hydrolysis, Biodegradation and Ion Sorption in Binary Biocomposites of Chitosan with Polyesters: Polylactide and Poly(3-Hydroxybutyrate).

The film binary composites polylactide (PLA)-chitosan and poly(3-hydroxybutyrate) (PHB)-chitosan have been fabricated and their functional characteristics, such as hydrolysis resistance, biodegradation in soil, and ion sorption behavior have been explored. It was established that hydrolysis temperature and acidity of solutions are differently affected by the weight loss of these two systems. Thus, in the HCl aqueous solutions, the stability of the PHB-chitosan composites is higher than the stability of the PLA-chitosan one, while the opposite situation was observed for biodegradation in soil. The sorption capacity of both composites to Fe3+ ions was investigated and it was shown that, for PHB-chitosan composites, the sorption is higher than for PLA-chitosan. It was established that kinetics of sorption obeys the pseudo-first-order equation and limiting values of sorption correspond to Henry's Law formalism. By scanning electron microscopy (SEM), the comparative investigation of initial films and films containing sorbed ions was made and the change of films surface after Fe3+ sorption is demonstrated. The findings presented could open a new horizon in the implementation of novel functional biodegradable composites.

Importance of Electron Mediator Transparency: Photocatalytic Hydrogen Production from Polyoxometalate using Dye‐double‐layered Photocatalysts

AbstractOne‐directional electron transfer is crucial for two‐step photoexcitation (Z‐scheme) water‐splitting photocatalysis. We investigated the hydrogen evolution activity of PS‐double‐layered photocatalysts (X‐DSP, X‐RuCP6‐Zr‐RuP6@Pt/KxH4‐xNb6O17; X=Zr4+, H+) in the presence of highly charged polyoxometalates‐K6[SiVIVW11O40] ⋅ nH2O (VIV‐POM) and K6[SiW11O39MnII(H2O)] ⋅ nH2O (MnII‐POM)‐as redox‐reversible electron donors, to induce effective photocatalyst‐donor electrostatic attraction. Surface‐phosphonate‐comprising H+‐DSP completely one‐electron oxidized VIV‐POM with 0.39 % apparent quantum yield in the initial hour (iAQY) in both HCl and phosphate buffer aqueous solutions. Conversely, the Zr4+‐DSP iAQY decreased to 0.05 % in HCl aq. Considering that the 0.39 % iAQY was retained when replacing VIV‐POM with MnII‐POM in HCl aq, we supposed that energy transfer deactivation from photoexcited PS* to surface‐immobilized VIV‐POM is the plausible origin of the lower iAQY, owing to the stronger visible‐light absorptivity of VIV‐POM. This suggests that accumulation of visible‐light‐transparent electron mediator on the photocatalyst surface is an effective approach for one‐directional electron transfer in Z‐scheme water‐splitting photocatalysis.

Synthesis of zeolite A from fly ash and its application in the slow release of urea

The study focused on the transformation of coal fly ash to zeolite A (ZA) as a potential carrier for the slow release of urea. After being treated with HCl aqueous solution and NaOH successively, SiO2 and Al2O3 were converted into sodium silicoaluminate. The obtained silicoaluminate was then heated with NaAlO2 in an aqueous NaOH solution at 70–110 °C for 3–18 h and zeolite A was successfully prepared according to the X-ray diffraction measurements. By changing the hydrothermal temperature and time, ZA could reach 237.3 mmol/100 g in maximum cation exchange capacity. ZA impregnated with urea (ZA-U) at a mass ratio of more than 5:1 exhibited slow release of urea and the kinetics release mechanism of ZA-U was proposed. The plant growth test proved that the slow release of urea from ZA-U can promote the growth of maize seedling.

Effects of Different Surface Treatments of Woven Glass Fibers on Mechanical Properties of an Acrylic Denture Base Material

Silanized glass fibers are popular reinforcements of acrylic denture base materials. To increase the number of surface hydroxyl groups and to improve interfacial adhesion between the matrix and reinforcements, acid or base treatments of glass fibers are commonly performed before the silanization. However, limited data are available on the effect of these treatments on the mechanical properties of acrylic matrix composite materials used for denture base applications. In this work, before the silanization of a woven glass fiber fabric (GF) with 3-(trimethoxysilyl) propyl methacrylate, activation pretreatments using HCl and NH4OH aqueous solutions have been performed. To characterize the glass surface, FTIR spectroscopy was used. Specimens of cured acrylic denture base resin and composites were divided into five groups: (1) cured acrylic denture base resin-control group; (2) composite with non-silanized GF; (3) composite with silanized GF; (4) composite with NH4OH activated and silanized GF; (5) composite with HCl activated and silanized GF. The flexural and impact properties of specimens were evaluated by means of three-point-bending tests and Charpy impact testing, respectively. The residual reactivity of the samples was analyzed using differential scanning calorimetry. The results of mechanical testing showed that acid and base pretreatments of the glass fabric had a positive effect on the flexural modulus of prepared composites but a negative effect on their impact strength. Possible interfacial adhesion mechanisms and the diffusion control of isothermal cure reactions due to vitrification have been discussed.

Extraction of Se(iv) and Se(vi) from aqueous HCl solution by using a diamide-containing tertiary amine.

Here, we investigated the mechanism underlying the extraction of Se(iv) and Se(vi) from aqueous HCl solutions by N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide)amine (EHBAA). In addition to examining extraction behavior, we also elucidated structural properties of the dominant Se species in solution. Two types of aqueous HCl solutions were prepared by dissolving a SeIV oxide or a SeVI salt. X-ray absorption near edge structure analyses revealed that Se(vi) was reduced to Se(iv) in 8 M HCl. Using 0.5 M EHBAA, ∼50% of Se(vi) was extracted from 0.5 M HCl. In contrast, Se(iv) was hardly extracted from 0.5 to 5 M HCl; however, at molar concentrations above 5 M, the extraction efficiency of Se(iv) increased drastically, reaching ∼85%. Slope analyses for the distribution ratios of Se(iv) in 8 M HCl and Se(vi) in 0.5 M HCl showed that apparent stoichiometries of Se(iv) or Se(vi) to EHBAA were 1 : 1 and 1 : 2, respectively. Extended X-ray absorption fine structure measurements revealed that the inner-sphere of the Se(iv) and Se(vi) complexes extracted with EHBAA was [SeOCl2] and [SeO4]2-, respectively. Together, these results indicate that Se(iv) is extracted from 8 M HCl with EHBAA via a solvation-type reaction, whereas Se(vi) is extracted from 0.5 M HCl via an anion-exchange-type reaction.

Стресс-тесты антраценпроизводных растительного происхождения

Objective: to study the stability of solutions of standard samples of sennoside B and glucofrangulin A by stress tests using high performance liquid chromatography (HPLC). Materials and methods. The objects of the study were solutions of standard samples of sennoside B, as well as glucofrangulin A. Stress agents were 0.5M aqueous solution of copper (II) chloride (CuCl2), 0.5M aqueous solution of iron (III) chloride (FeCl3), 0.1M aqueous solution of hydrochloric acid (HCl), as well as 0.1M aqueous solution of sodium hydroxide (NaOH) and a solution of hydrogen peroxide (H2O2) 3%. The study was carried out using an Agilent 1100 liquid chromatograph. For this purpose, a Zorbax SB-C18 reverse-phase column (4.6×250 mm, 5 µm) was used. Elution of the mobile phase (acetonitrile and highly purified water, which was adjusted to pH 2 with phosphoric acid) was carried out in a gradient mode. Detection was carried out at wavelengths of 360 nm and 435 nm. Results. It was found that a solution of a standard sample of glucofrangulin A is stable for 14 days under the influence of 0.1M aqueous solution of HCl and 0.1M aqueous solution of NaOH, as well as 0.5M aqueous solution of FeCl3 and 3% H2O2 solution. When a solution of a standard sample of glucofrangulin A interacts with a 0.5M aqueous solution of CuCl2, its destruction is observed. When a standard sample of sennoside B reacts with a 3% H2O2 solution and a 0.5M aqueous CuCl2 solution, it remains stable. When interacting with other stress agents, its destruction occurs. Conclusion. The results obtained on the stability of solutions of standard samples of anthracene derivatives determine the main physico-chemical factors that cause their destruction, which can be taken into account when validating analytical methods, justifying the conditions of storage, packaging and processing of medicinal plant materials that contain anthracene derivatives.

The Adsorption Equilibrium and Kinetic Studies for The Removal of Crystal Violet Dye (Methyl Violet 6b) from Aqueous Solution Using Avocado Pear Seed Activated Carbon

In this study, adsorption equilibrium and kinetic studies for the removal of crystal violet (CV) from an aqueous solution were investigated using a batch adsorption process. The activated carbon was prepared by carbonizing the avocado pear seed at a carbonization temperature of 500OC for 1hr and was impregnated with a 30% concentration of aqueous HCl solution which was further activated in a muffle furnace at a temperature of 500OC for 1hr. The avocado pear seed activated Carbon obtained was characterized using proximate analysis, Fourier Transform Infra-Red Spectrophotometer (FT-IR) analysis and Scanning Electron Microscope (SEM) analysis. The effect of various adsorption parameters such as contact time (15-150 min), initial dye concentration (25-150 mg/L), adsorbent dosage (1-9 g), particle size and pH of dye solution were investigated. The adsorption equilibrium data were fitted into different isotherm models and the Langmuir model exhibited the best fit which implied that the adsorption of CV dyes onto avocado pear seed activated carbon was monolayer and the adsorbent surface was homogeneous and also; adsorption energy was uniform for all sites and there was no transmigration of adsorbate in the plane of the surface. The kinetic studies revealed that the adsorption data fitted well to the pseudo-second-order model with a high correlation coefficient of 0.977 when compared to other models, thus; signifying that the adsorption’s mechanism was chemisorption. APSAC shows a much better adsorption capacity for CV dye removal having a maximum adsorption capacity of 3.3254 mg/g and percentage removal of 99.995 %. Hence, APSAC can be used as an effective and low-cost adsorbent for the removal of CV dye from an aqueous solution.

Study on Manufacturing and Applicability of Natural Adhesive for Paper Craft Using Corn Starch

A natural adhesive of starch (corn) that can be used to make and repair paper crafts was manufactured. The purpose of this study was to explore a composition of an adhesive having maximum adhesive strength while controlling a catalyst, a reaction initiator, and an oxidizing agent added to an aqueous starch solution at room temperature. The best composition was when a 35% starch aqueous solution was used. The 2.0% NaOH aqueous solution was added to the 35% starch aqueous solution to adjust pH from 10.0 to 11.0, and 0.20 g NiSO4, 20.0 g NaOCl, 30.0 g of 30.0% NaOH solution, and 3.0 g of 1.0% sodium thiosulfate were sequentially added. In the last step, the 3.0% HCl aqueous solution was added to adjust the pH of the adhesive to 7.5, and the adhesive strength of the prepared adhesive was 213 kgf/㎠. It was stable at room temperature for more than 60 days without physical changes such as viscosity, phase separation, precipitation, etc. In addition, TVOC, HCHO, and heavy metals were not detected, and the excellent result was found in antibacterial and reversible tests. This adhesive is an excellent natural adhesive that can be easily used by the user and does not contain harmful substances. It was an adhesive that could maintain the reputation of traditional materials in addition to their production and preservation.

One-step synthesis of heteropolyacid ionic liquid as co-extraction agent for recovery of lithium from aqueous solution with high magnesium/lithium ratio

The novel heteropolyacid ionic liquid 1-methylimidazolium silicotungstate ([Mmim]4SiW12O40) was synthesized using a one-step method and subsequently characterized. This compound was then employed as a co-extractant for the removal of lithium from salt lake brine having a high Mg/Li molar ratio, in conjunction with tributyl phosphate (TBP) and γ-heptanolide as the extractant and diluent, respectively. The optimal extraction conditions gave a single-stage lithium ion extraction efficiency of approximately 60 %. More environmentally friendly and efficient processes were also developed. In one approach, a portion of the aqueous phase containing only HCl and LiCl after stripping was used for washing along with an aqueous HCl solution as the stripping agent and Mg(OH)2 for regeneration. In the alternative method, NaCl and LiCl were used as washing agents while Na2CO3 was employed for stripping and regeneration, reducing the time required without the need for strong acids or bases. This system showed good extraction efficiency stability over 10 consecutive cycles. The mechanism of this process was explored using Fourier transform infrared spectroscopy and 31P nuclear magnetic resonance spectroscopy and the binding capacity of TBP for the metals was found to decrease in the order of Li+ > Na+ > Mg2+ > K+.

EVALUATION OF DESULPHURIZATION POTENTIALS OF BARIUM CHLORIDE, CALCIUM HYDROXIDE, SODIUM HYDROXIDE AND HYDROCHLORIC ACID ON DIESEL, KEROSENE AND GASOLINE

The sulphur content in refined petroleum products namely diesel (AGO), kerosene (DPK) and gasoline (PMS) obtained from a commercial Filling Station in Abakaliki, Ebonyi State were determined before and after desulphurization with aqueous ionic solutions of NaOH, BaCl2, Ca(OH)2 and HCl using a single beam UV-Vis spectrophotometer (Genesys 1OS, Thermo-Scientific). Results obtained showed that the amount of sulphur contained in the samples before desulphurization were 1.457, 0.992 and 1.294 mg/L in diesel, kerosene and gasoline respectively. The highest sulphur recovery of 0.676 mg/L (46.4 %), 0.315 mg/L (31.8 %), and 0.555 mg/L (42.9%) in diesel, gasoline and kerosene respectively were obtained with a 10 % w/v solution of NaOH after desulphurization. This was followed by a 10 % w/v solution of BaCl2 which gave 35.0 % and 23.0 % desulphurization in Diesel and gasoline respectively. The performance of Aqueous solutions of Ca(OH)2 and HCl in desulphurizing kerosene and gasoline were relatively low (3.2 %,11.4 % and 15 %, 4.6 % respectively) compared with aqueous NaOH. The results showed appreciable reduction in sulphur content of the samples with NaOH exhibiting the highest desulphurization potential in all the samples assayed. Thus these ionic solutions possess the potential to extract sulphur compounds in petroleum products.

Rheological behavior of the galactomannan fraction from Gleditsia triacanthos seed in aqueous dispersion

The purpose of the current study was to explore the influence of hydrochloric acid and sodium hydroxide, and sodium chloride on the rheological behavior of the galactomannan fraction from Gleditsia triacanthos seeds in aqueous solution. The flow (shear and extensional) and viscoelastic behavior as well as the dielectric properties were analyzed. The results indicated the existence of an interconnected microstructure, mainly in the macromolecular systems dispersed in HCl aqueous-solution, whose macromolecular arrangement leads to higher shear and extensional viscosity profiles, and contributes to improve the resistance to high shear deformation of this systems. The electrical conductivity profile of the Gledi -galactomannan in NaOH, HCl and NaCl aqueous-solution would indicate an increase or improvement in the continuity of the macromolecular arrangements compared to the polysaccharide in water. The conjugation of the galactomannan with Cl − ions would contribute to stabilize the microstructure. These results contribute to understand how the galactomannan fraction from Gleditsia triacanthos seeds could influence the microstructure and texture of ended-products, helping to consider its future applications. • Gledi -galactomannan in HCl-solution showed the highest shear and extensional viscosity. • Gledi -galactomannan developed a more interconected microstructure in HCl-solution. • HCl-solution improved the resistance of the Gledi -galactomannan arrangement. • Gledi -galactomannan and Cl − ions conjugation could contribute to stabilize the microstructure.

Effect of the solution acidic-basic property on the structure and photocatalytic performance of hydrothermally-synthesized TiO2

• Phase, shape and size-tunable hydrothermal synthesis of TiO 2 in different solutions. • The photocatalytic activities are H 2 O-TiO 2 > HAc-TiO 2 > HCl-TiO 2 > NaOH-TiO 2 . • The underlying reasons for the photocatalytic activity disparity were proposed. • Helpful for future synthesis of TiO 2 -based photocatalysts by hydrothermal method. The effect of the solution acidic-basic property on the structure and photocatalytic performance of hydrothermally-synthesized TiO 2 was investigated. It was found that the solution acidic-basic property influenced the phase, morphology and size of the obtained products. Anatase TiO 2 nanoparticles, anatase TiO 2 nanoparticles, and rutile TiO 2 nanorods were synthesized in deionized water, 1.818 mol/L HAC, and 1.818 mol/L HCl aqueous solution, respectively, but phase-pure TiO 2 cannot be synthesized in 1.818 mol/L NaOH aqueous solution. For photocatalytic reduction of aqueous Cr(VI) under Xe lamp irradiation, the TiO 2 synthesized in deionized water (H 2 O-TiO 2 ) demonstrated the best photocatalytic activity. The smallest grain size, biggest specific surface area, most surface hydroxyl groups and highest photogenerated charge separation efficiency may be responsible for the greatest photocatalytic activity of H 2 O-TiO 2 . Considering that hydrothermal method is most frequently used in synthesizing TiO 2 -based photocatalysts, our finding of pure water as the best solvent for hydrothermal synthesis of TiO 2 would have great significance and provide helpful guidance.

Construction and performance of CdS/MoO2@Mo2C-MXene photocatalyst for H2 production

Nowadays, photocatalytic technologies are regarded as promising strategies to solve energy problems, and various photocatalysts have been synthesized and explored. In this paper, a novel CdS/MoO2@Mo2C-MXene photocatalyst for H2 production was constructed by a two-step hydrothermal method, where MoO2@Mo2C-MXene acted as a binary co-catalyst. In the first hydrothermal step, MoO2 crystals with an egged shape grew on the surface of two-dimensional (2D) Mo2C MXene via an oxidation process in HCl aqueous solution. In the second hydrothermal step, CdS nanorods were uniformly assembled on the surface of MoO2@Mo2C-MXene in ethylenediamine with an inorganic cadmium source and organic sulfur source. The CdS/MoO2@Mo2C-MXene composite with MoO2@Mo2C-MXene of 5 wt% exhibits an ultrahigh visible-light photocatalytic H2 production activity of 22,672 µmol/(g·h), which is ∼21% higher than that of CdS/Mo2C-MXene. In the CdS/MoO2@Mo2C-MXene composite, the MoO2 with metallic nature separates CdS and Mo2C MXene, which acts as an electron-transport bridge between CdS and Mo2C MXene to accelerate the photoinduced electron transferring. Moreover, the energy band structure of CdS was changed by MoO2@Mo2C-MXene to suppress the recombination of photogenerated carriers. This novel compound delivers upgraded photocatalytic H2 evolution performance and a new pathway of preparing the low-cost photocatalyst to solve energy problems in the future.

Anti‐corrosion property of superhydrophobic copper mesh with one‐step self‐assembled perfluorothiolate monolayers

Copper mesh (CM) is one of the most commonly used engineering materials due to its remarkable mechanical and electromagnetic properties. However, CMs are generally susceptible to chemical corrosion in harsh environments, which greatly limits their long‐term usage. In this paper, we come up with a one‐step perfluorodecanethiol self‐assembly means to manufacture superhydrophobic CM with significantly improved anti‐corrosion property. The self‐assembly reaction between copper and 1H,1H,2H,2H‐perfluorodecanethiol created nanoscale rough structures and lowered the surface energy of the CM surface, which was account for the excellent repellence towards various aqueous solutions. The electrochemical tests demonstrated that, compared with original CM, the icorr value of the self‐assembled monolayers (SAMs) functionalized CM decreases about one order of magnitude, whereas the corrosion protection efficiency of the treated CM in NaCl, NaOH, and HCl aqueous solutions were all obviously increased. Therefore, the proposed simple method could be an alternative candidate for the creation of functional CM with anti‐corrosion properties that could be used under complex conditions.

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans / Cis Isomers

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing <i>Trans</i> / <i>Cis</i> Isomers

Single‐Step Synthesis of Exfoliated Ti3C2Tx MXene through NaBF4/HCl Etching as Electrode Material for Asymmetric Supercapacitor

AbstractTwo‐dimensional Ti3C2Tx MXene, derived from the parent Ti3AlC2 phase, is considered a promising electrode material for electrochemical energy storage applications. Ti3C2Tx MXene synthesis methods often employ concentrated hydrofluoric acid (HF), which is harsh, corrosive, and hazardous to the environment. Herein, we report the preparation of Ti3C2Tx MXene following a new synthetic route under a mild reaction condition comprising an aqueous solution of NaBF4 and HCl. This etching environment at a moderate temperature of 130 °C effectively removes the Al layer of the Ti3AlC2 precursor, assisted by the in situ formed HF in the reaction medium. Electron microscopy images of the as‐prepared Ti3C2Tx (MX‐130) reveal a partially exfoliated nanosheet‐like morphology. The material displays a specific capacitance of 262 F g−1 (three‐electrode assembly, 1 A g−1, −0.85 to −0.25 V vs. Hg/Hg2SO4) in 1 M H2SO4 electrolyte. The achieved specific capacitance is superior to that of Ti3C2Tx prepared via the common HF‐treatment (25 F g−1). Additionally, the potential application of the optimized MXene as a negative electrode material is demonstrated in a quasi‐solid‐state RuO2|MX‐130 asymmetric supercapacitor device.

Use of Time Domain Nuclear Magnetic Resonance Relaxometry to Monitor the Effect of Magnetic Field on the Copper Corrosion Rate in Real Time

The corrosion of metals is a major problem of modern societies, demanding new technologies and studies to understand and minimize it. Here we evaluated the effect of a magnetic field (B) on the corrosion of copper in aqueous HCl solution under open circuit potential. The corrosion product, Cu2+, is a paramagnetic ion and its concentration in the solution was determined in real time in the corrosion cell by time-domain NMR relaxometry. The results show that the magnetic field (B = 0.23 T) of the time-domain NMR instrument reduces the corrosion rate by almost 50%, in comparison to when the corrosion reaction is performed in the absence of B. Atomic force microscopy and X-ray diffraction results of the analysis of the corroded surfaces reveal a detectable CuCl phase and an altered morphology when B is present. The protective effect of B was explained by magnetic forces that maintain the Cu2+ in the solution/metal interface for a longer time, hindering the arrival of the new corrosive agents, and leading to the formation of a CuCl phase, which may contribute to the rougher surface. The time-domain NMR method proved to be useful to study the effect of B in the corrosion of other metals or other corrosive liquid media when the reactions produce or consume paramagnetic ions.

Aminopolycarboxylic Acids-Functionalized Chitosan-Based Composite Cryogels as Valuable Heavy Metal Ions Sorbents: Fixed-Bed Column Studies and Theoretical Analysis.

Over the years, a large number of sorption experiments using the aminopolycarboxylic acid (APCA)-functionalized adsorbents were carried out in batch conditions, but prospective research should also be directed towards column studies to check their industrial/commercial feasibility. In this context, sorption studies of five-component heavy metal ion (HMI) solutions containing Zn2+, Pb2+, Cd2+, Ni2+, and Co2+ in equimolar concentrations were assessed in fixed-bed columns using some APCA-functionalized chitosan-clinoptilolite (CS-CPL) cryogel sorbents in comparison to unmodified composite materials. The overall sorption tendency of the APCA-functionalized composite sorbents followed the sequence Co2+ < Zn2+ < Cd2+ ≤ Pb2+ < Ni2+, meaning that Co2+ ions had the lowest affinity for the sorbent’s functional groups, whereas the Ni2+ ions were strongly and preferentially adsorbed. To get more insights into the application of the composite microbeads into continuous flow set-up, the kinetic data were described by Thomas and Yoon–Nelson models. A maximum theoretical HMI sorption capacity of 145.55 mg/g and a 50% breakthrough time of 121.5 min were estimated for the column containing CSEDTA-CPL cryogel sorbents; both values were much higher than those obtained for the column filled with pristine CS-CPL sorbents. In addition, desorption of HMIs from the composite microbeads in dynamic conditions was successfully achieved using 0.1 M HCl aqueous solution. Moreover, a theoretical analysis of APCA structures attached to composite adsorbents and their spatial structures within the complex combinations with transition metals was systematically performed. Starting from the most stable conformer of EDTA, coordinative combinations with HMIs can be obtained with an energy consumption of only 1 kcal/mole, which is enough to shift the spatial structure into a favorable conformation for HMI chelation.