Presence Of HCl Research Articles

Microwave-Assisted Synthesis of Bis-(Hydroxybenzylidene)-Cycloalkanones via Acid Catalyzed Claisen-Schmidt Condensation

In the present study, bis-(hydroxybenzylidene)cycloalkanone derivatives were synthesized by Claisen-Schmidt condensation using cycloalkanones and arylaldehydes in the presence of HCl as an acid catalyst. The synthetic reaction was carried out under microwave irradiation. The structure of the synthesized compounds was determined by UV, IR, 1H NMR spectroscopic methods. The obtained reaction yields were not optimal due to the self-polymerization of p-hydroxybenzaldehyde in an acid solution.

Regioselectivity and physical nature of the interactions between (methyl)guanine with HCl and CH3OH

A comprehensive study of the hydrogen bonding interactions between guanine (G) and methyl guanine derivatives (MGs) in the presence of HCl and MeOH is carried out at B3LYP, B3LYP-D3 and M062X/6–311 + + G(d.p) levels using molecular electrostatic potential, natural bond orbital, and symmetry adapted perturbation theory. Making use of these state-of-the-art techniques, this study attempts to elucidate the chemical bonding, regioselectivity, and physical nature of the interactions responsible for the stability of (M)G…L (L = HCl, MeOH) acid–base complexes. Our calculations reveal that 1-G, 3-MG, and 5-MG interact more strongly with MeOH than HCl due to the positive hydrogen bond cooperativity. Furthermore, the carbonyl site on G is found to be the most reactive site, while methyl substitution increases the basicity of the nucleobase, thus yieding more stable complexes. The strongest H-bond interaction in G-complexes is found when HCl and MeOH attack the carbonyl group in anti-position. Finally, energy decomposition analyses through the symmetry-adapted perturbation theory reveal that most complexes are mainly stabilized via electrostatic interactions. The energy difference between complex isomers shows a competition between 3-HCl-G (MG) and 4-HCl-G (MG) at ∆G level where thermal, BSSE and entropy terms are included.

Optimization of synthesis parameters for polyamide 610: Strategic tailoring for superior latent heat performance

The study systematically optimizes the synthesis of polyamide 610 with the aim of improving latent heat and melting temperature to meet the demanding requirements of high-temperature heat storage applications using Response Surface Methodology (RSM). The results clarify the critical impact of reaction times, washing solvents, and molar ratios on these vital thermal characteristics. Samples exhibiting exceptional latent heat capacities at various mole ratios were further analyzed using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD). The TGA assessments were instrumental in determining the thermal degradation behaviors of the materials. At the same time, The DSC analysis was used for the determination of thermal properties of the materials, FTIR provided detailed insights into their molecular structures, and XRD elucidated the crystalline structure of the materials. The findings reveal that a specific mole ratio is essential for achieving superior thermal properties, indicative of the polymer's resilience and structural stability. It was evident that samples with a balanced molar ratio (1:1) and specific reaction time (60 min) showed the best latent heat, surpassing 80 J g-1, and melting temperatures up to 210 °C. A notable aspect of this research is the use of Sebacic Acid instead of the conventional Sebacoyl Chloride for synthesizing polyamide 610. The choice of Sebacic Acid was made due to its lower toxicity and the fact that its byproducts are easier to remove than those from sebacoyl chloride, which produces hydrochloric acid as a byproduct. The presence of HCL can lead to side reactions and negatively impact the reaction process. By using Sebacic Acid, we reduce the risk of such contaminants, thereby enhancing the thermal stability and performance of polyamide 610. This greener approach not only aligns with sustainable practices but also has significant implications for the performance of the polymer. In addition, the integration of RSM with comprehensive characterization techniques has been pivotal in elucidating the critical influence of synthesis parameters on material properties. This enhanced understanding holds the potential for significant contributions to the development of advanced materials for latent heat storage applications, combining sustainability with high performance.

Sandmeyer Chlorosulfonylation of (Hetero)Aromatic Amines Using DABSO as an SO2 Surrogate.

Sulfonyl chlorides not only play a crucial role in protecting group chemistry but also are important starting materials in the synthesis of sulfonamides, which are in-demand motifs in drug discovery chemistry. Despite their importance, the number of different synthetic approaches to sulfonyl chlorides is limited, and most of them rely on traditional oxidative chlorination chemistry from thiol precursors. In this report, we disclose a novel Sandmeyer-type sulfonyl chloride synthesis from feedstock anilines and DABSO, used as a stable SO2 surrogate, in the presence of HCl and a Cu catalyst. The method works on a wide range of anilines and allows for the isolation of the sulfonyl chloride after aqueous workup or its direct conversion into the sulfonamide by simple addition of an amine after the completion of the Sandmeyer reaction. The scalability of this method was demonstrated on a 20 g scale, and the corresponding heterocyclic sulfonyl chloride was isolated in 80% yield and excellent purity.

Enhancing photocatalytic degradation of rhodamine B with visible-light-driven HCl-assisted Bi2O3 photocatalysts: Activity, mechanism, and pathways

This study utilized X-diffraction, BET, photoluminescence, UV–vis DRS, FTIR, SEM, XPS, TOC analysis, EPR, electrochemical measurements, and LC-MS to characterize the structural characteristics, morphology, optical properties, photocatalytic activity, surface electronic states, active compounds, and potential photodegradation pathways of rhodamine B (RhB) over as-prepared Bi2O3. The as-prepared Bi2O3 photocatalyst exhibited a narrow bandgap, which enabled efficient absorption of visible light, thereby contributing to its enhanced photocatalytic activity. Additionally, Bi2O3 exhibited a high degradation efficiency for RhB. with up to 96.8 % of RhB removed within 120 min at pH 3.0. The excellent photocatalytic performance of Bi2O3 can be attributed to the formation of the heterogeneous Bi2O3/BiOCl structure on the Bi2O3 surface in the presence of HCl. Moreover, the TOC analysis revealed that over 58.1 % of the carbon in the RhB solution was mineralized into CO2 after 120 min of irradiation. The effect of catalyst content, RhB concentration, initial pH, and inorganic anions on the photocatalytic degradation of RhB over Bi2O3 was examined. Furthermore, the active compounds and potential photocatalytic mechanism of the Bi2O3/BiOCl heterogeneous structure toward RhB were evaluated. The intermediates formed during RhB degradation were identified, and the corresponding degradation pathway was deduced via LC-MS.

Impact of gas composition (CO, H2, and HCl) on chemical looping combustion by SiO2 supported oxygen carriers

A great oxygen carrier for chemical looping combustion (CLC) supports the carbon capture activity. In this study, Fe2O3, NiO, and Mn2O3 are prepared on SiO2 support for test in CLC under various operating conditions. The best utilization value of 100 % was performed by 20%Fe2O3/SiO2 and stability was presented up to 10 redox cycles. 20%Fe2O3/SiO2 was used for the following study with the presence of HCl. Combination of HCl and CO in the inlet gas had insignificant changes. Differently, a drastic improvement achieved by combination with H2. However, the presence of HCl in multiple cycles test led to pore enlargement, surface area reduction, and decline in performance of 20%Fe2O3/SiO2. The presence of H2O and CO2 from the exhausted gas after the reaction indicated the efficient and complete reaction of the 20 % Fe2O3/SiO2. Besides, analysis of the reaction kinetics with Type I deactivation mode performed a well fitted result.

Study of mesomorphism behavior and protonation-induced emission of symmetrical benzalazines

Rod-shaped and polycatenar symmetric benzalazines with protonation-induced emission were synthesized, characterized, and studied for their thermal and optical behavior. Benzalazines lacking hydroxy groups at the ortho position did not show luminescence in the solid state or solution. In the presence of HCl (either in solution or vapor form) these compounds became good emitters. The protonation of azine nitrogen that may hinder the NN bond rotation by intermolecular interactions toward aggregates provided an explanation for the emission characteristics observed. The protonation-induced emission was thermally reversible. A benzalazine derived from 4-alkoxysalicylaldehyde with AIE property was prepared. For this compound with ortho-OH groups, the optical properties were not affected by the presence of acidic media. It exhibited a stable SmC phase characterized by POM, DSC, and XRD. The luminescence capability of the molecular arrangement within the smectic phase was investigated. The intense yellow-green emission in the crystals decreased significantly at the phase transition due to the non-radiative decay that occurs with increasing temperature, and loss of intermolecular H-bonding which prevents molecular rotations in the crystal.

Unlocking high-performance HCl adsorption at elevated temperatures: the synthesis and characterization of robust Ca–Mg–Al mixed oxides

The presence of HCl and SO2 gas imposes limitations on syngas utilization obtained from household waste in a wide range of applications. The hydrotalcite-like compounds (HTLs) have been proved that could remove HCl efficiency. However, the research on impact of synthesis conditions of HTLs and SO2 on HCl removal was limited. In this study, a range of Ca–Mg–Al mixed oxide sorbents was synthesized by calcining HTLs, with variations in crystallization temperature, solution pH, and the Ca/Mg molar ratio. These sorbents were examined for their effectiveness in removing HCl at medium–high temperatures under diverse conditions. The adsorption performance of selected sorbents for the removal of HCl, SO2, and HCl-SO2 mixed gas at temperature of 350 °C, 450 °C, and 550 °C, respectively, was evaluated using thermogravimetric analysis (TGA). It was observed that the HTL synthesis parameters significantly influenced the HCl adsorption capacity of Ca–Mg–Al mixed oxides. Notably, HTLs synthesized at 60 °C, a solution pH of 10–11, and a Ca/Mg ratio of 4 exhibited superior crystallinity and optimal adsorption characteristics. For individual HCl and SO2 removal, temperature had a minor effect on HCl adsorption but significantly impacted SO2 adsorption rates. At temperatures above 550 °C, SO2 removal efficiency substantially decreased. When exposed to a mixed gas, the Ca–Mg–Al mixed oxides could efficiently remove both HCl and SO2 at temperatures below 550 °C, with HCl dominating the adsorption process at higher temperatures. This dual-action capability is attributed to several mechanisms through which HTL sorbents interacted with HCl, including pore filling, ion exchange, and cation exchange. Initially, HCl absorbed onto specific sites created by water and CO2 removal due to the surface’s polarity. Subsequently, HCl reacted with CaCO3 and CaO formed during HTL decomposition.Graphical abstract

High-temperature reaction chemistry of chromium and chlorine over Fe2O3 within sludge-incinerated fly ash

Fe2O3 is one of the main compositions of sludge-incinerated fly ash and shows reactivity for chromium removal from flue gas in the incinerator. Experiments and density functional theory (DFT) calculations were performed to investigate the high-temperature reaction chemistry of chromium and chlorine over Fe2O3 within fly ash. Fe2O3 exhibits outstanding chromium removal efficiency of 86.29 % in N2 atmosphere. The presence of HCl obviously inhibits chromium removal, the inhibition effect increases with increasing HCl concentration. Fe-Cr composite oxides are the main products of chromium-Fe2O3 high-temperature reaction. Chromium within the reaction products in N2 or HCl-containing atmosphere mainly exists in the form of Cr3+. O2 addition leads to the formation of a small amount of Cr6+. Fe2O3 exhibits excellent inhibition performance of chromium oxidation. DFT calculations suggest that CrCl3 and CrO2Cl2 are chemically adsorbed on Fe2O3 surface. Both O and Fe atoms of Fe2O3 surface serve as active sites for chromium adsorption. HCl is dissociatively adsorbed on the Fe2O3 surface, and reacted with chromium to form CrCl3. CrCl3 formation on the Fe2O3 surface is dominated by a four-step reaction pathway: Cr(ads) → CrCl(ads) → CrCl2(ads) → CrCl3(ads) → CrCl3. CrCl formation is the rate-determining step with the energy barrier of 39.51 kJ/mol.

Insight into the catalytic behavior of ionic liquids and deactivation suppression technique in naphthalene alkylation

Lewis acidic ionic liquids as catalysts for alkylation reactions exhibited the potential for industrial application. Herein, the catalytic behavior of AlCl3-based ionic liquids with four organic ammonium salts was studied in the alkylation of naphthalene with n-octene for production of lubricating base oil, with special focus on the deactivation and recovery of ionic liquid. The Et3NHCl-AlCl3 ionic liquid exhibited better catalytic performance than others due to its stronger interaction with naphthalene, as evidenced by the adsorption test of naphthalene over ionic liquids. To understand the deactivation mechanism, the deactivated catalysts were extensively characterized by FT-IR and UV–vis. The protonation effect of ionic liquids on polyalkylation products in the presence of HCl was found to aggravate the deactivation of ionic liquid. The negative effect is easily reversed by the decompression treatment on the reaction system before catalyst recovery, this method markedly enhanced the cycling durability of ionic liquids for industrial application.

Migration and transformation mechanisms of Pb/Cd with HCl in organic solid waste incineration flue gas on the composite-modified kaolinite surface

Cadmium/lead (Cd/Pb) pollutants from organic solid wastes (OSW) incineration are of global concern due to high volatility and biotoxicity. The strong interaction between modified kaolinite and Cd/Pb species inspires its utilization for the elimination of heavy metals. However, the specific mechanism of the migration and transformation of Cd/Pb species is yet unclear. Consequently, the migration and transformation mechanisms of Cd/Pb species on the modified kaolinite (001) surface are examined by density functional theory (DFT), considering the effect of HCl. The outcomes show that the HCl significantly alters the characteristics of the kaolinite, which enhances the surface activity of kaolinite and promotes the adsorption and transformation of Cd/Pb species. Furthermore, the chlorination routes of Cd0/Pb0 are fully elucidated in both 2-step and 1-step routes. The first step of the 2-step route obeys the Langmuir-Hinshelwood mechanism and the second step obeys the Eley-Rideal mechanism, while the 1-step chlorination route obeys the Eley-Rideal mechanism. In addition, the oxidation route of Cd0/Pb0 follows the Mars-van Krevelen mechanism. The comparison of the energy barriers shows that the 1-step Cd0/Pb0 chlorination route has the lowest energy barrier. The kaolinite surface is found to have elevated activity for the adsorptive trapping of Cd/Pb species in the presence of HCl, which offers a preliminary theoretical framework for pollutant control on the modified kaolinite surface.

Multifunctional Polypyrrole-Based Textile Sensors for Integration into Personal Protection Equipment.

Integrated safety sensors for personal protection equipment increasingly attract research activities as there is a high need for workers in delicate situations to be physically monitored in order to avoid accidents. In this work, we present a simple approach to generate thin, homogeneous polypyrrole (PPy) layers on flexible textile polyamide fabrics. PPy layers of 0.5-1 µm were deposited on the fabric, which thus kept its flexibility. The conductive layers are multifunctional and can act as temperature and gas sensors for the detection of corrosive gases such as HCl and NH3. Using three examples of life-threatening environments, we were able to monitor temperature, atmospheric NH3 and HCl within critical ranges, i.e., 100 to 400 ppm for ammonia and 20 to 100 ppm for HCl. In the presence of HCl, a decrease in resistance was observed, while gaseous NH3 led to an increase in resistance. The sensor signal thus allows for distinguishing between these two gases and indicating critical concentrations. The simple and cheap manufacturing of such PPy sensors is of substantial interest for the future design of multifunction functional sensors in protective clothing.

Green industry work: production of FeCl3 from iron and steel industry waste (mill scale) and its use in wastewater treatment

Mill scale (MS) is considered to be a significant metallurgical waste, but there is no economical method yet to utilize its metal content. In this study, which covers various processes in several stages, the solution of iron in MS, which is the Iron and Steel Industry (I&SI) waste, as FeCl3 (MS-FeCl3) in the thermoreactor in the presence of HCl, was investigated. In the next step, the conditions for using this solution as a coagulant in the treatment of I&SI wastewater were investigated using the jar test. The results of the treated water sample were compared by chemical oxygen demand (COD), total suspended solids (TSS), color, and turbidity analyses using commercial aluminum sulfate (Al2(SO4)3) and FeCl3 (C-FeCl3). Additionally, heavy metal analyses were conducted, and the treatment performance of three coagulants was presented. Accordingly, while 2.0 mg/L anionic polyelectrolyte was consumed at a dosage of 4.05 mg/L Al2(SO4)3 at pH 7.0, 0.25 mg/L anionic polyelectrolyte was consumed at a dosage of 1.29 mg/L at pH 5.0 in the C-FeCl3 and MS-FeCl3 studies. Also, Fe, Cr, Mn, Ni, Zn, Cd, Hg, and Pb removal efficiencies were over 93.56% for all three coagulant usage cases. The results showed that the wastewater treatment performance of MS-FeCl3 by the recycling of MS, which is an I&SI waste, was at the same level as C-FeCl3. Thus, thanks to recycling, waste scale can be used as an alternative to commercial products for green production.Graphical abstract

Revelation of HCl poisoning and enhancement mechanism on N-modified Al2O3 catalysts for COS and CS2 hydrolysis

The presence of HCl in blast furnace gas significantly inhibits hydrolytic activity and catalyst stability. The anti-chlorine capacity and poisoning mechanism of Al2O3 catalysts before and after nitrogen modification was investigated by activity evaluation, characterization analysis and theoretical calculations. In the presence of 0.01 vol% HCl, the COS and CS2 conversions of K0.1Al2O3 catalysts decreased rapidly after 4 h of reaction, which was amended by N doping. The N0.1K0.1Al2O3 catalyst maintained 48.23 % COS conversion and 45.41 % CS2 conversion, respectively, after 16 h reaction. The deteriorated reactivity was mainly associated with the decreased specific surface area, reduced chemisorbed oxygen, disrupted basicity and COS and CS2 adsorption ability. Sulfate and HCl on the surface of the unmodified catalyst mainly destroyed the Al sites and led to catalyst deactivation. N doping reinforced the tendency of toxic molecules to adsorb at the K site (K2SO4 and KCl) and thus protected the Al active site. DFT calculation results demonstrated the inhibition of HCl adsorption at the Al site by N modification, while the trapping of HCl by both K and N sites efficiently protected the Al site from acidification. The reaction pathway calculations certified that N doping increased the energy barrier of the HCl dissociation reaction, which inhibited the acidification and deactivation of Al2O3 to some extent.

Ultraviolet-Visible Absorption Spectroscopy of MoCl5, MoOCl4, and MoO2Cl2 Vapors.

This article reports quantitative absorption spectra for MoCl5, MoOCl4, and MoO2Cl2 in the vapor phase from 45,500 to 15,500 cm-1 (645 to 220 nm). Spectra are obtained in an ultrahigh purity stainless steel vacuum system by rapidly sampling a range of analyte partial pressures. The short measurement times and the differential absorbance method employed here minimize effects from uncontrolled transients such as window deposits. A detailed analysis of replicate measurements and time-resolved spectra shows generally reproducible spectral response from MoCl5 vapors at 120 °C. The presence of HCl and MoOCl4 impurities in the MoCl5 vapor samples is determined to be unlikely based on the analysis of absorbance-pressure curves and spectral peak fitting. Comparison with MoOCl4 and MoO2Cl2 spectra shows a unique spectral fingerprint for MoCl5 at 28,500 cm-1 providing a convenient means of discriminating between MoCl5 and its oxychlorides in the visible wavelengths. Adsorption behavior of MoCl5 on surfaces is also discussed with particular emphasis on the use of MoCl5 as a reactant in vapor phase thin film deposition processes.

Removal of Base Metals from Mine Tailings in Chloride- and Seawater-Based Media Followed by Solvent Extraction

The high volume of mine tailings generated during mining activities poses significant worldwide storage risks. However, these tailings often contain valuable metals that can be recovered. Therefore, reprocessing mine tailings has emerged as a crucial strategy to assess secondary metals resources and mitigate storage risks. Furthermore, the mining industry’s extensive use of freshwater necessitates exploring alternative water sources. In this study, the leaching of base metals from mine tailings in chloride-based media was investigated. Approximately 52% Cu, 73% Zn, and 100% Pb were leached from the sample in the presence of HCl and NaCl. The substitution of freshwater with seawater yielded comparable results, demonstrating the potential of seawater as an alternative freshwater source that does not compromise leaching effectiveness. Additionally, 77% of Pb precipitated as PbSO4 from the pregnant leach solution. Through solvent extraction, approximately 100% Cu was recovered using LIX 984 as an extractant, and 71% Zn with D2EHPA. The use of Fe0 significantly reduced the co-extraction of Fe in the Zn recovery step. Overall, this study provides a potential route for reprocessing mine tailings, ensuring maximum leaching and efficient recovery of metals from sulfide mine tailings.

From Formyl-Corroles to Non-Aromatic Porphyrinoids

In 1998, it would have been impossible to imagine that only 20 years later the chemistry of one of corroles would expand to create an independent field of study. The synthesis of corroles has undergone incredible changes. From multistep strategies that attracted only practitioners in the field, the procedure has been transformed into a one-pot process from commercially available reagents. The synthesis of meso-substituted corroles evolved quickly during the first seven years after Paolesse’s and Gross’s discovery [1,2]. The methodology which led to trans-A2B-corroles (i.e., corroles bearing substituents A at positions 5 and 15 and substituent B at position 10) from dipyrranes and aldehydes was discovered in 2000 and optimized several times prior to 2006, when we discovered that as long as aldehydes and dipyrranes were relatively small and/or hydrophilic, performing this reaction in a mixture of water and methanol in the presence of HCl allowed the yields to increase from 6-30% to ~55% [3,4]. The synthetic revolution made it possible to try risky ideas in diverse areas of materials chemistry and in various biology- and medicine-oriented applications. Multiple challenges still remain in the preparation of corroles.One of those challenges is the preparation of corroles possessing CHO groups. Free formyl groups can be reacted with multiple nucleophiles forming more complex and more advanced structures. At the same time CHO is the reacting group pivotal in the corrole synthesis. Attempting to solve this conundrum we recently developed the synthesis of tris(4-formylphenyl)corrole in straightforward fashion. During the realization of this project we discovered that 10-(2-formylphenyl)corrole undergoes intramolecular Friedel-Crafts reaction leading to non-aromatic, π-expanded corrole. This divalent macrocycle possess intriguing photophysical properties and has an ability to form complexes with various metals.References Gross, Z.; Galili, N.; Saltsman, I. Angew. Chem. Int. Ed. 1999, 38, 1427−1429.Paolesse, R.; Jaquinod, L.; Nurco, D. J.; Mini, S.; Sagone, F.; Boschi, T.; Smith, K. M. Chem. Commun. 1999, 1307−1308.Koszarna, B.; Gryko, D. T. J. Org. Chem. 2006, 71, 3707−3717.Orłowski, R.; Gryko, D.; Gryko, D. T. Chem. Rev. 2017, 117, 3102-3137. Figure 1

Study on the competitive absorption between complex components in flue gas and SO3 by alkaline absorbent

SO3 in coal-fired flue gas will cause equipment corrosion and the emission of sulfuric acid mist. The complex component in the flue gas will affect the performance of alkaline absorbent. In this study, a fixed bed reactor was used to evaluate the absorption performance of SO3 by a variety of absorbents. Then, on this basis, the competition between SO3 and SO2, SO3 and HCl were studied by the fixed bed reactor. The effect of oxygen on the competitive absorption of SO3 and SO2 by absorbents was also investigated. Further, when SO2, HCl and SO3 existed simultaneously, the competitive reactions between multiple gases were investigated. The influence of SO2 and HCl on SO3 absorption was evaluated. Carbonate absorbents had stronger absorption capacity than other absorbents. In the adsorption process of SO3 by Na2CO3, the presence of SO2 inhibited the absorption of SO3 by Na2CO3, and oxygen oxidized Na2SO3 to produce Na2SO4, which affected the reaction between SO3 and Na2CO3.There was strong competition between SO3 and SO2. In the process of SO3 adsorption by Na2CO3, the presence of HCl had an inhibitory effect on the absorption of SO3, SO3 could significantly inhibit the absorption of HCl. When SO2, HCl and SO3 existed simultaneously, SO2 had a stronger influence on the adsorption of SO3 by Na2CO3 and the presence of HCl had little inhibition on the absorption of SO3 by Na2CO3. The inhibition effect of SO2 on SO3 and the inhibition of HCl on SO3 did not accumulate.

Structural and gelling properties of whey proteins influenced by various acids: Experimental and computational approaches

Five different acids, i.e., hydrochloric acid (HCl), acetic acid, lactic acid, γ-aminobutyric acid (GABA) and taurine were applied to investigated their effects on heat-induced gelation properties of whey protein isolate (WPI) at pH = 5.5. All WPI gels were found to have self-similar structures with the fractal dimension, df = 2.40. Those denatured WPI formed strong physical gels that were susceptible to shear and strain. Of all the acids, HCl, GABA and taurine significantly strengthened WPI gels. Moreover, denser packing of protein aggregates was observed from the gels with GABA and taurine. Besides experimental approaches, molecular dynamics (MD) simulations were also applied to investigate the effects of various acids on denaturation of β-lactoglobulin (β-LG). GABA and taurine were found to protect β-LG from denaturation and delayed the molecular heat-induced unfolding. Moreover, presence of HCl, GABA and taurine conserved the rigidity of unfolded β-LG and localized the residue –SH121, which was believed to result in promoted reaction-limited clustering aggregations (RLCA) of β-LG molecules and strengthened WPI gels. Further studies suggested that there was no strong binding or aggregation between cations (Na+) or anions/zwitterions and β-LG molecule. Therefore, the effects from various acids (anions/zwitterions) on β-LG and WPI were supposed to result from long-distanced electrostatic interactions and/or their effects on the protein hydration shells.

DFT study of mercury adsorption on Al2O3 with presence of HCl

mercury emission control from flue gas is a crucial issue for environment protection. Alumina is an important alkali metal oxide for mercury adsorption in particulate, meanwhile is the potential adsorbent for mercury removal. The cognition on mercury heterogeneous reaction mechanism with alumina in presence of hydrogen chloride is inadequate. In this work, the DFT calculation was applied to detect mercury's chlorides adsorption on α-Al2O3 (001) surface, the Bader charge analysis was used to estimate electron transfer and the transition state theory was used to clarify reaction pathway and energy barrier, besides, the kinetic analysis based on Gibbs free energy was conducted to study the impact of temperature on chemical reaction. The results show that Hg can be captured by weak chemisorption on α-Al2O3 (001) surface with the adsorption energy of −56.37 kJ/mol, HgCl, HgCl2 are intensively bonded on surface with adsorption energies of −276.90 kJ/mol and −231.87 kJ/mol, the surface unsaturated Al and O atoms are the active sites. Charge transfer and PDOS analysis prove that the forming of covalent bonding is responsible for Hg species adsorption. Two possible reaction pathways of Hg oxidization to HgCl2 are discussed, in which a smaller energy barrier of 0.1 eV implies the dominant pathway 1 via Eley-Rideal mechanism: two adsorbed HCl molecules dissociate on surface and then react with one Hg atom. High temperature can promote the reaction rate constants of pathway 1 and 2, but is only favorable for reducing energy barrier of pathway 2.