Hydroxyl Content Research Articles

Investigation of hydroxyl-terminated polydimethylsiloxane-modified epoxy resin

Epoxy resin coatings are characterized by a high concentration of hydroxyl groups, making them inherently hydrophilic and prone to corrosion. Additionally, the brittleness of epoxy resin limits its practical uses. In this study, epoxy resin (EP-51) was modified using hydroxyl-terminated polydimethylsiloxane (HTPDMS), which possesses a low surface energy due to its -Si-O- bonds, to improve the hydrophobicity and toughness of the coating. The effect of varying HTPDMS concentrations on the properties of epoxy resin was evaluated in terms of mechanical, thermodynamic, and electrochemical properties, as well as contact angle measurements. The findings reveal that as the HTPDMS content increases, the tensile strength of the modified EP diminishes, while the elongation and impact strength are enhanced. However, higher HTPDMS levels lead to reduced compatibility with EP, causing phase separation and the formation of an “island structure”. The glass transition temperature of the EP declines with added HTPDMS, resulting in an increased swelling rate and reduced pencil hardness and adhesion grade of the coatings. Notably, the hydrophobicity of the EP improved significantly, with its contact angle rising from 74.8° to 99.0° post-modification. Electrochemical impedance spectroscopy and polarization curve analyses revealed optimal protective performance of the coating at an epoxy resin to HTPDMS mass ratio of 8:2.

Experimental study on the effect of room temperature pre-oxidized time on spontaneous combustion characteristics of coal

The presence of different types of coal at room temperature can lead to self-heating of coal, potentially resulting in spontaneous combustion. To investigate the effect of ambient temperature pre-oxidation (BL) time on the self-combustion characteristics of different coal types, synchronous thermal analysis (STA) and Fourier-transform infrared spectroscopy (FTIR) experiments were conducted. The results of the synchronous thermal analysis experiments indicate that ambient temperature pre-oxidation for 3 months (BL3), BL6, and BL9 coals exhibit faster oxidation reactions compared to the original coal, while BL12 coal shows slower oxidation than the original coal. Among these, BL9 coal demonstrates the most significant changes in oxidation reaction characteristics, with the fastest oxidation reaction time being 35.36 min, which is 1.38 min faster than the original coal. To support this observation, a comparison was made between the relative content of active functional groups in the original coal and BL coal. The study revealed that the BL process affects the relative content of hydroxyl groups, aromatic hydrocarbons, aliphatic hydrocarbons, and oxygen-containing functional groups, thereby influencing the coal-oxygen reaction process. This suggests that pre-oxidized coal, compared to the original coal, has a larger pore structure, which plays a dominant role in promoting coal self-combustion in the first 9 months of the BL process. As BL time continues to increase, the continuous reaction of active functional groups at room temperature leads to excessive consumption, resulting in a more significant role in inhibiting coal self-combustion. The research results provide valuable insights for predicting the spontaneous combustion risk of oxidized coal.

Spectroscopic properties and numerical analysis of novel erbium doped multi-component tellurite glasses

In this paper, Er3+ doped TeO2-ZnF2-BaF2-KF-Ta2O5 tellurite glasses with low hydroxyl content (∼0.03 × 10−19 cm−3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 μm of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 10−21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems.

Bovine hide collagen/tannin extract composite: A revelation of the selective structure-activity relationship between phenolic hydroxyls and Cu(Ⅱ) and study on adsorption properties

In this paper, phenolic compounds are employed to reveal that there is a selective structure-activity relationship between adjacent phenolic hydroxyls in tannin of bovine hide collagen/tannin extract composite (BHC/TE) and Cu(Ⅱ). Firstly, the morphology and structure of BHC/TE are observed via SEM, TEM and BET. Then, the preparation and adsorption mechanisms of BHC/TE are revealed via XPS, FT-IR and DFT. Meanwhile, four common adsorption models are used to jointly explore the adsorption mechanism. In addition, phenol, resorcinol, hydroquinone, catechol and pyrogallol are employed to investigate the effect of content and location of phenolic hydroxyls on the adsorption of Cu(Ⅱ) by employing UV–visible spectra, fluorescence spectra and DFT calculation. Finally, the adsorption properties of BHC/TE are also discussed. Therefore, this paper aims to confirm the selective structure-activity relationship between adjacent phenolic hydroxyls and Cu(Ⅱ), and it also provides a new idea for future research and structure design of related adsorbents.

Study of hydroxyl and nitrite radicals concentration in plasma-activated water by photoluminescence spectroscopy

The atmospheric pressure plasma in water has numerous applications, including utilizing reactive species in the dye degradation process for polluted water remediation. In the current study, an air plasma jet generated atmospheric pressure plasma, transporting reactive oxygen and nitrogen species (RONS) onto the solution surface, such as OH and NO2 radicals, which immediately developed in an aqueous solution. The identification and concentration of radicals are determined using photoluminescence spectroscopy (PL) and irradiation over the surface of an aqueous solution. Based on the reaction between hydroxyl ions and terephthalic acid, fluorimetric methods for hydroxyl ions determination are developed. In addition, 2,3-diamino naphthalene was selected for the nitrite reaction. The jet nozzle-to-solution-surface distance, treatment time, and carrier air flow rate substantially impacted determining the radical’s concentration in aqueous solution.

Fractionation of lignin using eco-friendly organic cosolvent and preparation of light-colored lignin micro-nanoparticles for sustainable natural sunscreens

The inherent challenges posed by lignin, such as its high heterogeneity, complex structure and dark color, have impeded its widespread high-value utilization. In the present study, a green cosolvent system comprising ethanol (EtOH) and dimethyl carbonate (DMC) was employed for the fractional separation of alkali lignin. Through careful manipulation of the solvent ratio, interactions between the solvents and lignin were effectively regulated, leading to the reduction of lignin heterogeneity and the isolation of lignin fractions with distinct properties. Notably, a high yield of up to 35.65% of lignin with desirable characteristics, including a light color, low molecular weight, and high hydroxyl groups content, was achieved. Furthermore, this specific lignin fraction exhibited enhanced UV absorption and antioxidative properties, rendering it highly suitable for potential applications in sun protection products. When incorporated as micro-nano particles, it exhibited great compatibility with hand creams and elevated their sun protection factor (SPF). This innovative approach not only presents a green and straightforward lignin fractionation process but also highlights the untapped potential of lignin in the realm of sun protection applications.

Cd-CeO2@C: Synthesis via consumption of Cd2+ and organic pollutants and removal of organic pollutants

In this study, a Cd-CeO2@C photocatalyst was produced via the calcination of a precursor (Cd-Ce(OH)4@AR14) obtained by co-precipitation of Ce(NO3)3·6H2O, Cd(NO3)2·4H2O and acid red 14 (AR14). The structure, composition, morphology, and optical properties of the synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectrum (FT-IR), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS) and Photoluminescence Spectroscopy (PL). The photocatalytic activity of the synthetized materials was evaluated by performing the degradation of AR14. The results showed that the band gap of CeO2 could be effectively reduced by Cd-doping, and that carbon bonds could decrease the recombination rate of photogenerated electrons and holes, resulting in enhancing the photocatalytic efficiency of the synthesized materials compared with that of pure CeO2. Hydroxyl groups play an important role in the photocatalysis because the adsorption of AR14 over Cd-CeO2@C is greatly affected by the content of hydroxyl groups. Moreover, effect of oxygen vacancies on the photocatalytic efficiency was investigated and the results showed that oxygen vacancies could improve the photocatalytic efficiency of the resulted samples.

Elucidating the role of active oxygen species and hydroxyl groups in the furfural base-free oxidation to furoic acid over δ-MnO2

δ-MnO2 shows potential application in furfural base-free oxidation to furoic acid. While, its catalytic mechanism was unclear, which limited the further improvement of the catalytic activity. Therefore, three δ crystal MnO2 with different hydroxyl and active oxygen species concentrations were prepared and applied in the furfural oxidation reaction. IR, Furfural-IR, O2-TPD, H2O-18O2-TPD, and XPS techniques characterized the hydroxyl and active oxygen species. The results show that the hydroxyl group on δ-MnO2 is important in absorbing and attacking furfural to form geminal diol intermediate. Moreover, two types of oxygen species O-OH and Oads originating from the surface hydroxyl and the strongly adsorbed gas-phase O2, respectively, play an essential role in defhydrogenating geminal diol to furoic acid. Most importantly, the hydroxyl, O-OH, and Oads consumed on δ-MnO2 can be reconstructed under reaction conditions. Among the three δ crystal MnO2, δ-MnO2, with the most abundant hydroxyl and active oxygen species, exhibited the best catalytic performance with 99.53% furfural conversion and nearly 100% furoic acid selectivity. This work identifies the function of hydroxyl and active oxygen species on δ-MnO2 in furfural oxidation reaction, guiding the design of a non-noble metal catalyst for furoic acid synthesis under base-free conditions.

Polydopamine coated polyvinyl alcohol sponges as floatable co-catalysts for boosting the CaO2/Fe3+ system in dye degradation

Polydopamine (PDA) has shown charming co-catalytic activity in the classical Fenton and Fenton-like reactions. However, the improvement is merely attributed to the Fe2+ regeneration ability of PDA. The co-catalytic role and cycling stability of PDA in the CaO2 based Fenton-like reaction have been rarely explored despite CaO2 is considered safer than the liquid H2O2. In this study, floatable co-catalysts were fabricated by coating PDA on polyvinyl alcohol (PVA) sponges. It is proven that in the composite can accelerate not only the Fe3+ reduction but also the reaction between Fe2+ and H2O2 released by CaO2. Therefore, lower concentrations of Fe2+ and H2O2 in the CaO2/Fe3+ Fenton-like system were detected respectively, along with higher efficiency in Rhodamine B (RhB) removal. In addition, in the reusing test, the RhB degradation still maintained at 81.2% after the fifth cycle. The reasons for the decreased activity were carefully investigated. First, the RhB adsorption is largely disturbed by the Ca2+ and Fe3+/Fe2+ ions adsorbed during the reaction. Secondly, both declined Fe2+ regeneration and H2O2 consumption were observed, due to the reduced content of phenolic hydroxyl groups on the PDA surface.

Polymerized PEI-modified lignin polyphenolic materials by acid hydrolysis-phase separation for removal of Cr (VI) from industrial wastewater

Cr (VI) accumulates in an aqueous environment and exhibits huge harm to human health and the ecological system. Developed lignin biomass materials are complicated to prepare and have limited properties, and advances in lignin phenolic modification are lacking. Herein, an aminated poplar lignin-pyrogallol (PLP-PEI) with a simple design and adjustable phenolic hydroxyl content was developed using the acid hydrolysis-phase separation (AH-PS) method, and modified by the atom transfer radical polymerization (ATRP) strategy. Through diverse characterization analysis, the structural changes of PLP-PEI in the step-by-step synthesis process were monitored. An effective biomass capture system (Bio-Cap) was shown via systematically investigating the adsorption behaviors of Cr (VI) on PLP-PEI under various environmental conditions. Benefiting from introducing phenolic hydroxyl and amino groups, PLP-PEI demonstrated efficient adsorption capacity (598.80 mg/g for Cr (VI)). Additionally, the material also exhibited advantages, including monomeric chemisorption properties, strong reduction capability, and stable regeneration properties. Multiple driving forces were involved in the capture and removal process of Cr (VI), including complexation and electrostatic interaction. The low-cost natural biomass resources supported the industrial-scale synthesis and practical application of advanced aminated lignin polyphenol material, which showed outstanding advantages and enormous potential in the field of water environmental restoration.

Evolution and oxidation properties of the functional groups of coals after water immersion and air drying

The evolution of functional groups, the gas generation laws in oxidation and temperature increase, and the oxidation kinetics parameters of the coal samples immersed in water for 30 days, 90 days, and 150 days (hereinafter referred to as 30 d coal, 90 d coal, and 150 d coal, respectively) were analyzed through Fourier transform infrared spectrometer, programmed temperature increase test system, and thermal gravimetric analyzer to disclose spontaneous combustion and the influencing mechanism of long-flame coals immersed in water for a long period. Results show that the aliphatic hydrocarbon and the hydroxyl contents of the coal samples increase after water immersion and air drying. In particular, the aliphatic hydrocarbon contents in 30 d coal, 90 d coal, and 150 d coal increase from 12.61 % for raw coal to 15.84 %, 14.08 %, and 13.90 %, respectively, whereas the hydroxyl content increases from 48.75 % for raw coal to 50.77 %, 50.13 %, and 49.23 %, respectively. In the low-temperature oxidation process, the CO output increases, and the apparent activation energy declines. When the temperature is 200 °C, the CO outputs of 30 d coal, 90 d coal, and 150 d coal are 28088, 25421, and 22112 ppm, which are 37.4 %, 24.4 %, and 8.2 % higher than the CO output of raw coal (20437 ppm), respectively. The apparent activation energy decreases from 65.7 kJ mol−1 for raw coal to 61.12 kJ mol−1, 63.08 kJ mol−1, and 64.5 kJ mol−1. According to the comparison of characteristic temperature points, the temperature of the mass extreme (T3) and the temperature of ignition point (T4) of the immersed coal samples both decrease. The T3 values of 30 d coal, 90 d coal, and 150 d coal decrease from 282.71 °C for raw coal to 274.87, 278.33, and 280.50 °C, whereas their T4 values decrease from 424.24 °C for raw coal to 419.23, 420.14, and 423.42 °C, respectively. This study proves that water immersion increases the oxidative activity of coals, thereby simplifying spontaneous combustion.

Multi-scale utilization of lignin: A catalytic hydrogenation strategy based on catechyl lignin nanoparticles

With an abundance of oxygen-containing groups on the hydrophilic shell of lignin nanoparticles (LNPs), this biomaterial can serve as a catalytic support to adsorb and load metals. Herein, catechyl lignin oligomers from castor seed coats (Cas) were extracted via solvothermal pretreatment and prepared as LNPs using the solvent shifting method. Pd2+ ions were then stabilized and reduced in situ on the surface of LNPs, which were further utilized for the catalyzed hydrogenation of lignin-derived aldehydes. Due to the homogeneous building units and linear linkages, the lignin oligomers from Cas exhibited superior self-assembly capacity with a lower π-π interaction energy than those from conventional lignocelluloses, resulting in a high yield of LNPs with a smooth surface. The high content of phenolic hydroxyl groups in catechyl-dominant LNPs resulted in efficient Pd2+ ions adsorption via chemisorption of monomolecular layer and a partial reduction of the Pd2+ ions into metallic states. In addition, the Cas-derived Pd/LNPs exhibited exceptional catalytic activity for the hydrogenation of lignin-derived aldehydes with high selectivity to alcohols under mild conditions. This could be attributed to the interaction preference of the reaction substrate according to the construction of LNPs: strong hydrogen bond between the aldehyde group of the substrate and the hydrophilic shell of LNPs, as well as the hindered π-π interactions between the benzene ring of the substrate and the hidden hydrophobic core of LNPs. This study, therefore, successfully employed lignin with a broad range of molecular weights from oligomers to monomers, paving the way for a comprehensive lignin biorefining industry.

Remediation of diesel-oil contaminated soils using an innovative nanobubble and electrolyzed catalytic system

Soil contamination resulting from petroleum hydrocarbons poses a significant environmental challenge. In this research, an innovative electrolyzed catalytic system was devised to produce nanobubble-enriched catalytic water, which was employed for remediating soils contaminated with diesel oil. This novel system harnessed high voltage (220 V) via direct current, utilizing titanium electrodes coated with iridium dioxide. The inclusion of iron-copper hybrid oxide catalysts between the electrodes was instrumental in enhancing the efficiency of radical generation. The study employed the electron paramagnetic resonance (EPR) technique and the Rhodamine B (RhB) method to analyze the species and concentration of the generated radicals. EPR is a versatile tool for investigating materials with unpaired electrons and is capable of quantifying reaction kinetics for transition metals. RhB can be used as a probe for hydroxyl radical concentration determination. The addition of an electrolyte (NaCl or K2SO4) could enhance the electrolytic reaction and improve radical production rate. By incorporating 20 mM of K2SO4 and utilizing 75 g of catalyst per 500 mL batch of nanobubble-contained electrolyzed catalytic water (NECW) production, with a current density of 20 mA/cm2, a highly oxidized nanobubble-infused electrolyzed catalytic water was successfully generated. This water exhibited an oxidation-reduction potential of 887 mV and contained a radical concentration of 7.6 × 10−13 M, encompassing hydroxyl, superoxide, and sulfate radicals. Furthermore, it displayed a negative zeta potential of −39.8 mV, along with nanobubbles averaging 28 nm in diameter and a nanobubble density of 3.7 × 109 particles per milliliter. The presence of nanobubbles in electrolyzed catalytic water, owing to their negative zeta potential and nano-scale attributes, imparts a repulsive force that hinders bubble aggregation and prolongs their existence. When these nanobubbles burst, the resulting radicals contribute to an augmented radical concentration, which, in turn, facilitates the oxidation of petroleum hydrocarbons. Approximately 72.4% of the total petroleum hydrocarbon in soils could be removed (dropped from 3230 mg/kg to 892 mg/kg) after five batches of NECW washing (10 min of each washing time) via the desorption and extended chemical oxidation mechanisms. The total petroleum hydrocarbons in the water phase could be removed entirely after pumping the polluted water into the electrolyzed catalytic system for immediate treatment, indicating that the electrolyzed catalytic system could oxidize the desorbed total petroleum hydrocarbon effectively. The findings demonstrate that the nanobubble-infused catalytic water generated by the innovative electrolyzed system effectively and efficiently remediates petroleum-hydrocarbon-contaminated soils and water, all while minimizing the risk of secondary pollution.

Exploring the factors influencing the low temperature CO gas production characteristics of low-metamorphic coal

CO as an important indicator gas for predicting early spontaneous combustion of coal mainly comes from the oxidation of residual coal in goaf. Low-metamorphic coal has a stronger tendency for spontaneous combustion and is more prone to oxidation to produce CO gas at low temperatures. For example, there are no signs of natural combustion in certain goaf areas of mines, but the CO concentration in the working face continues to exceed the limit, which misleads early natural combustion prediction and warning work. Therefore, taking low metamorphic coal as the main research object, the CO gas production characteristics of different coal samples at low temperatures were determined through temperature-programmed experiments. It was found that the CO gas production rate and concentration of CYM at low temperatures were much higher than those of the other two metamorphic coal samples (approximately 2 times RNM and 3–10 times QM); Determination of content and proportion changes of hydroxyl, aliphatic, Aromatic hydrocarbon and oxygen-containing functional groups in different coal samples before and after heating by Fourier transform infrared spectroscopy. Based on the analysis of CO gas production characteristics of different coal samples, it was found that the intermolecular hydrogen bonds in the hydroxyl groups of CYM and the C-O bonds in the oxygen-containing functional groups decreased significantly. The strongest correlation between intermolecular hydrogen bonds in hydroxyl groups and C-O bonds in oxygen-containing functional groups and the low-temperature CO gas production characteristics of coal is demonstrated; Finally, scanning electron microscopy was used to study the differences in apparent characteristics of different coal samples before and after heating, to determine more complex apparent structures that increase oxygen adsorption sites and promote low-temperature oxidation and CO production of coal during the low-temperature stage. Further guidance will be given to the research on the suppression of intermolecular hydrogen bonds and C-O bonds, as well as the sealing of coal micro pores and crack structures, to improve the targeted application and fire prevention efficiency of fire prevention materials.

Novel synergistically effects of palladium-iron bimetal and manganese carbonate carrier for catalytic oxidation of formaldehyde at room temperature

The elimination of formaldehyde at room temperature holds immense potential for various applications, and the incorporation of a catalyst rich in surface hydroxyl groups and oxygen significantly enhances its catalytic activity towards formaldehyde oxidation. By employing a coprecipitation method, we successfully achieved a palladium domain confined within the manganese carbonate lattice and doped with iron. This synergistic effect between highly dispersed palladium and iron greatly amplifies the concentration of surface hydroxyl groups and oxygen on the catalyst, thereby enabling complete oxidation of formaldehyde at ambient conditions. The proposed method facilitates the formation of domain-limited palladium within the MnCO3 lattice, thereby enhancing the dispersion of palladium and facilitating its partial incorporation into the MnCO3 lattice. Consequently, this approach promotes increased exposure of active sites and enhances the catalyst's capacity for oxygen activation. The co-doping of iron effectively splits the doping sites of palladium to further enhance its dispersion, while simultaneously modifying the electronic modification of the catalyst to alter formaldehyde's adsorption strength on it. Manganese carbonate exhibits superior adsorption capability for activated surface hydroxyl groups due to the presence of carbonate. In situ infrared testing revealed that dioxymethylene and formate are primary products resulting from catalytic oxidation of formaldehyde, with catalyst surface oxygen and hydroxyl groups playing a crucial role in intermediate product decomposition and oxidation. This study provides novel insights for designing palladium-based catalysts.

Depolymerisation of Kraft Lignin by Tailor-Made Alkaliphilic Fungal Laccases.

Lignins released in the black liquors of kraft pulp mills are an underutilised source of aromatics. Due to their phenol oxidase activity, laccases from ligninolytic fungi are suitable biocatalysts to depolymerise kraft lignins, which are characterised by their elevated phenolic content. However, the alkaline conditions necessary to solubilise kraft lignins make it difficult to use fungal laccases whose activity is inherently acidic. We recently developed through enzyme-directed evolution high-redox potential laccases active and stable at pH 10. Here, the ability of these tailor-made alkaliphilic fungal laccases to oxidise, demethylate, and depolymerise eucalyptus kraft lignin at pH 10 is evidenced by the increment in the content of phenolic hydroxyl and carbonyl groups, the methanol released, and the appearance of lower molecular weight moieties after laccase treatment. Nonetheless, in a second assay carried out with higher enzyme and lignin concentrations, these changes were accompanied by a strong increase in the molecular weight and content of β-O-4 and β-5 linkages of the main lignin fraction, indicating that repolymerisation of the oxidised products prevails in one-pot reactions. To prevent it, we finally conducted the enzymatic reaction in a bench-scale reactor coupled to a membrane separation system and were able to prove the depolymerisation of kraft lignin by high-redox alkaliphilic laccase.

From hydroxyl group to carbonyl group: Tuning the supercapacitive performance of holey graphene

Both hydroxyl group and carbonyl group are the inborn active sites on graphene for energy storage. However, it is difficult to distinguish the definite influence of these functional groups on the supercapacitive performance of graphene due to the considerable changes of total oxygen content (TOC) when adjusting the content of hydroxyl group and carbonyl group on graphene. In this paper, holey graphene was prepared by reoxidation method with ammonium persulfate as oxidant. During the reducing process, four kinds of reductant (formaldehyde, sodium borohydride, vitamin C and glucose) were used to optimize the TOC of graphene. Then, the directional tuning of the content of hydroxyl group and carbonyl group on graphene under a stable TOC was achieved by controlling the addition amount of specific reductant. Results from morphological and electrochemical analysis suggest that high carbonyl content leads to a fluffier graphene structure, bigger specific surface area, higher specific capacitance and lower ion diffusion resistance while high hydroxyl group content results in wider operating potential window and better electrical conductivity. After balancing the content of hydroxyl and carbonyl group in the holey graphene, the assembled supercapacitor owns the high energy density of 22 Wh·Kg−1 and excellent cycling performance (no capacity loss after 10 000 charge-discharge cycles).

Toward well-defined colloidal particles: Efficient fractionation of lignin by a multi-solvent strategy

Colloidal lignin particles (CLPs) have sparked various intriguing insights toward bio-polymeric materials and triggered many lignin-featured innovative applications. Here, we report a multi-solvent sequential fractionation methodology integrating green solvents of acetone, 1-butanol, and ethanol to fractionate industrial lignin for CLPs fabrication. Through a rationally designed fractionation strategy, multigrade lignin fractions with variable hydroxyl group contents, molecular weights, and high purity were obtained without altering their original chemical structures. CLPs with well-defined morphology, narrow size distribution, excellent thermal stability, and long-term colloidal stability can be obtained by rational selection of lignin fractions. We further elucidated that trace elements (S, N) were reorganized onto the near-surface area of CLPs from lignin fractions during the formation process in the form of -SO42− and -NH2. This work provides a sustainable and efficient strategy for refining industrial lignin into high-quality fractions and an in-depth insight into the CLPs formation process, holding great promise for enriching the existing libraries of colloidal materials.

Core-shell deAlY@SiO2 composite: A superior adsorbent for toluene capture under humidity condition

Y zeolite has been regarded as an effective adsorbent in removal of volatile organic compounds (VOCs). However, the low Si/Al ratio causes Y zeolite to preferentially adsorb water when dealing with wet VOCs, which limits its practical application. In present work, Y zeolite was first dealuminated treated by steaming and acid etching, and then the obtained deAlY was used as cores to prepare deAlY@nSiO2 core–shell composites. The shell layer thickness in the as-prepared core–shell composites was adjusted by controlling the hydrolysis of tetraethoxysilane (TEOS). The Si-species yielded from the hydrolysis of TEOS not only fabricated the mesopore shell directed by CTA+, but also entered the zeolite framework by polycondensation with the adjacent hydroxyl (silicon hydroxyl of (SiO)3Si(OH) species or aluminum hydroxyl of penta-coordinated aluminum caused by steaming and acid etching) in the defect sites of the core deAlY. During the adsorption of dry toluene, the as-synthesized composite displayed an adsorption capacity superior to mesopore SiO2 while inferior to deAlY. When toluene and water molecules competed for the adsorption sites, the core–shell composite preferred to adsorb the former because of the greatly reduced sensitivity to the presence of water vapor. Under 55 % and 83 % relative humidity, the core–shell deAlY@nSiO2 (n < 1.5) respectively had 4.2 and 9.0 times higher toluene adsorption than the deAlY. The mesopores in the SiO2 shell was conducive to a fast mass transfer, the high hydrophobic surfaces (internal and external) resulted from reduced hydroxyl content, elevated framework Si/Al ratio and constructed SiO2 shell, contributed to shielding water, which promoted toluene in the wet VOCs to be adsorbed efficiently by the deAlY zeolite core.

Comparative Sb(V) removal efficacy of different iron oxides from textile wastewater: effects of co-existing anions and dye compounds.

Elevated Sb(V) concentration in textile wastewater is a growing environmental concern worldwide and has received wider attention in recent years. Iron oxides possess appealing characteristics as efficient and cost-effective adsorbents in large-scale applications. In the present study, Sb(V) adsorption capacity of α-Fe2O3, γ-Fe2O3, and Fe3O4 was compared under experimental conditions close to the practical textile wastewater treatment. Results demonstrated that α-Fe2O3 performed better under different pH values, reaction times, dye compounds, and co-existing ions as compared to γ-Fe2O3 and Fe3O4, and the adsorption equilibrium was achieved within 8h. Sb(V) adsorption is found to be highly pH dependent, and higher removal was achieved in lower pH, indicating the involvement of electrostatic interactions. The pHpzc value of α-Fe2O3 was 7.15, which favored Sb(V) adsorption in practical wastewater having neutral pH value (pH ~ 7). Pseudo-first- and pseudo-second-order described the data and the simulated values of qe fitted well with the experimental values, indicating that pseudo-second-order model described the adsorption kinetics better with R2 (> 0.95) higher than of pseudo-first-order plots. The Langmuir and Freundlich models both described well the sorption data of all the adsorbents, where the R2 values were > 0.90 with a better fit in the Freundlich model for α-Fe2O3, suggesting that the adsorbent has heterogeneous surface characteristics. Similarly, characterizations revealed that the specific surface area, pore volume, and hydroxyl group content in α-Fe2O3 were higher than others, making it easier for contaminants to bind on to the active sites. Furthermore, the effect of dyes and co-existing anions on Sb(V) adsorption was negligible, except for SO42-, CO32-, and PO43- by the formation of inner-sphere complexes with iron oxides through competitive adsorption with [Sb(OH)6]-. Findings from the present study suggested that α-Fe2O3 effectively reduced Sb(V) in textile wastewater and could be a promising alternative for practical textile wastewater treatment.