Mean Pore Diameter Research Articles

A novel trimesoyl chloride/hyper branched polyethyleneimine/MOF (MIL-303)/P84 co-polyimide nanocomposite mixed matrix membranes with an ultra-thin surface cross linking layer for removing toxic heavy metal ions from wastewater

In this study, a positively charged nanofiltration (NF) nanocomposite mixed matrix membrane (MMM) was developed by incorporating metal-organic frameworks (MOFs) (MIL-303) into P84 co-polyimide and cross-linking with hyperbranched polyethyleneimine (HPEI). A very thin selective layer was subsequently formed on the cross-linked membrane surface using trimesoyl chloride (TMC). The incorporation of MIL-303 introduced specific water channels, enhancing the permeance of the nanocomposite MMMs. Additionally, it improved hydrophilicity and influenced the diffusion of the TMC monomer through the channels. The cross-linker HPEI resulted in NF membranes with increased electro-positivity and a reduced mean pore diameter. The very thin crosslinked TMC layer further improved permeance and heavy metal ions rejection of the membrane. This optimized membrane exhibited excellent rejection for both bivalent and monovalent ions, as well as heavy metal ions, effectively overcoming the common trade-off between permeance and rejection in NF membranes. The membrane demonstrated a remarkable permeance of 13.0 LMH/bar, coupled with exceptional rejection for heavy metal ions (96.8 % for Zn²⁺, 95.2 % for Ni²⁺, 95.7 % for Cu²⁺, 93.2 % for Pb²⁺, and 92.9 % for Cd²⁺). The TMC/HPEI/MIL-303/P84 system presented in this study holds significant promise for customizing high-performance positively charged NF membranes for the removal of heavy metal ions from wastewater.

Synchronous vacuum hot pressing ultra-high performance geopolymer: Ultrafast polymerization and early strength development

To overcome the application bottleneck of geopolymer in high-end industries, this study aims to develop ultra-high performance geopolymer products. By employing Synchronous Vacuum Hot Pressing, we have significantly enhanced the rate of polymerization and mechanical properties of Geopolymer based on Metakaolin-Fly Ash. The influence of Si/Al ratio, alkali equivalent, and molding time on the geopolymerization process, mechanical properties, and microstructure of geopolymers was investigated, while elucidating the underlying mechanisms. The compressive strength of SVHP-MFG reaches 90.92 MPa when the Si/Al ratio is 2, alkali equivalent is 8 %, and molding time is 30 min, owing to increased production of aluminosilicate gels and matrix structure densification. The ongoing reaction of unreacted particles and the subsequent transformation from "alumina-rich gel" to "silica-rich gel" in later stages further enhance the mechanical properties of the material. Additionally, the mean pore diameter of Synchronous vacuum hot pressing of metakaolin-fly ash geopolymer measures below 13.24 nm, thereby significantly enhancing the pore structure of the geopolymer. The synchronous vacuum hot pressing metakaolin fly ash-based geopolymers synthesized in this study represents a novel category of ultra-high performance ceramic-like geopolymers, exhibiting exceptional early strength and early stability. The research aims to promote the application of geopolymer in high-end industry and provide technical and theoretical support for the development of ultra-high performance geopolymer based products.

A facile and green synthesis of corn cob-based graphene oxide and its modification with corn cob-K2CO3 for efficient removal of methylene blue dye: Adsorption mechanism, isotherm, and kinetic studies

In recent years, the treatment of synthetic dyes has become an environmental concern. In this study, a single step calcination process was used to develop the inventive, simple, and inexpensive adsorbent CC-GO/CC-K2CO3 composite. The composite was employed for the treatment of methylene blue (MB), a cationic dye. Several characterization methods including powder XRD, FTIR, XPS, BET, FESEM, EDX, Raman, and HRTEM techniques were utilized for the analysis of the composite. The surface area and mean pore diameter of CC-GO/CC-K2CO3 were 32.651 m2 g−1 and 3.71 nm, respectively. The adsorption experiment showed that optimal parameters for the removal of MB dye are at an adsorbent dose of 60 mg, initial dye concentration of 80 mg/L, contact time of 150 min, and pH value of 12 at room temperature. Under optimized conditions, CC-GO evidences a removal efficiency of 70.34 ± 1.36 % while after incorporation with CC-K2CO3 the removal capacity sharply increases up to 98.10 ± 0.4 %. Kinetic and isotherm models were used to analyze the removal rate constant and equilibrium adsorption capacity under various adsorption environments. The adsorption study was found to follow the models of pseudo-second order kinetic and Freundlich isotherm. The CC-GO/CC-K2CO3 composite has the maximum adsorption capacity (MAC) of 160.77 mg/g established by the Langmuir isotherm. The prepared composite has demonstrated the capacity to be recycled up to three times with a gradual decrease in its adsorption behavior, exhibiting removal efficiency of 61.66 ± 2.04 %.A cost estimation study of the composite was also performed to assess its cost effectiveness.

Mesoporous Silica Administration as a New Strategy in the Management of Warfarin Toxicity; In Vitro and In Vivo Study

Purpose: Warfarin is one of the most widely used anticoagulants that function by inhibiting vitamin K epoxide reductase. Warfarin overdose, whether intentional or unintentional, can cause life-threatening bleeding. Here, we present a novel warfarin adsorbent based on mesoporous silica that can act as an antidote to warfarin toxicity. Method: Amino-functionalized mesoporous silica (MS-NH2) was synthesized based on co-condensation method through a soft template technique followed by template removal. The prepared structure and functional group were studied by FT-IR, XRD. The morphology was checked by SEM and TEM. The capacity of MS-NH2 in the adsorption of warfarin was evaluated in vitro, at pH=7.4 and pH=1.2. In vivo evaluation was performed in control and warfarin-overdosed animal models. Overdosed animals were treated with MS-NH2 by oral gavage. Biomarkers of organ injury were assessed in animal serum. Results: The MS-NH2 were relatively uniform, spherical with defined diameters (400 nm) and homogeneous structure. synthesized particles had a large surface area (1015 m2 g-1) and mean pore diameter 2.4 nm which leaded considerable adsorption capacity for warfarin 1666 mg/g. In vivo studies revealed that oral administration of MS-NH2 in mice poisoned with warfarin caused a significant difference (p < 0.05) on International Normalized Ratio (INR) and prothrombin time (PT). Moreover, the warfarin with MS-NH2 group demonstrated a notable decrease in biomarkers associated with tissue damage, such as bilirubin, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Conclusion: The results confirm that MS-NH2 administration can be an effective treatment for warfarin toxicity and could potentially mitigate the adverse effects of warfarin poisoning.

Transformation of Organic Cacao (Theobroma cacao) Husk into Commercial

Introduction: agroindustrial wastes can be transformed to mitigate the negative impacts associated with their disposal. In cocoa production, cocoa pod husk (CPH) constitutes between 67% and 76% of the total cocoa weight. This study focuses on the potential of CPH as a valuable resource for producing activated carbon, cellulose, and potassium hydroxide (KOH)..Objective: The objective of this research was to characterize and transform the CPH obtained from an organic crop in San Bernardo-Ibagué (Colombia) into activated carbon, cellulose, and KOH.Methods: activated carbon was produced through chemical activation using KOH, with a specific procedure for characterizing the obtained product through thermal analysis (TGA) and nitrogen adsorption and desorption isotherms. For cellulose extraction, an alkaline treatment with 2% w/w NaOH was followed by a bleaching process with 2.5% w/w sodium hypochlorite. KOH was obtained by first extracting potassium carbonate and then causticizing it.Results: activated carbon (AC) was produced with a yield of 25.6%, exhibiting a surface area of 468 m²/g, a mean pore diameter of 10.8 nm, and a total pore volume of 0.228 cm³/g, with 60% fixed carbon, 27% volatile material, 6% ash, and 6% moisture. Conclusions: the transformation of cocoa pod husk into activated carbon, cellulose, and KOH provides a sustainable approach to managing agroindustrial waste, generating valuable products with significant potential for various applications. The results obtained demonstrate the feasibility of utilizing CPH as a resource in agroindustrial processes.

Highly efficient adsorption of eosin yellow dye from aqueous solutions using polymer-based nanocomposite developed from cross-linked chitosan-citrate and Co2O3 nanoparticles

The utilization of polymer-based nanocomposites offers a particularly interesting method for removing organic dyes from waterways. This study aimed to efficient removal of eosin yellow (EOY) dye from aqueous solutions using polymer-based nanocomposite (hereinafter, CHA-CIT/Co2O3 NPs) prepared from crosslinked chitosan-citrate (CHA-CIT) and Co2O3 nanoparticles (Co2O3 NPs). The CHA-CIT/Co2O3 NPs adsorbent was investigated by several approaches like XRD, BET analysis, FTIR spectroscopy, FESEM-EDX, and pHpzc analysis, to get a thorough understanding of its structural and chemical characteristics. Box-Behnken design (BBD) was adopted to systematically optimize crucial adsorption parameters, including CHA-CIT/Co2O3 NPs dose (0.01–0.07 g), starting solution pH (4–10), and contact duration (10–40 min). The CHA-CIT/Co2O3 NPs nanocomposite's BET surface area was found to be 19.85 m2/g. The mean pore diameter was determined to be 4.3 nm, and the total pore volume was measured to be 0.0213 cm3/g. The average crystallite size of 23.22 nm is indicative of the CHA-CIT/Co2O3 NPs nanocomposite's mainly polycrystalline characteristics. The kinetic investigations showed an agreement with the pseudo-first-order model, while the equilibrium results agreed well with the Freundlich isotherm model, suggesting the presence of multilayer adsorption behavior. The adsorption capacity of CHA-CIT/Co2O3 NPs for EOY was found to be 650.03 mg/g at a temperature of 25 °C, highlighting its exceptional adsorption ability. The work introduces a novel and efficient chitosan nanocomposite as a potential adsorbent for the high-performance removal of organic dyes from water-based solutions.

The effect of phosphoric acid on the properties of activated carbons made from Myrtus communis leaves: Textural characteristics, surface chemistry, and capacity to adsorb methyl orange

In this work, chemical activation was employed to produce activated carbons and assess the impact of phosphoric acid (H3PO4) on their physicochemical properties. Using Myrtus communis Leaves (MC-Leaves) as the precursor and varying H3PO4 impregnation ratios (30 %, 60 %, 100 %, and 150 wt.%). The activation was conducted at 450 °C (10 °C/min) for 1 h in a room atmosphere. The effects of H3PO4 were evaluated through various techniques, including BET surface area analysis, FESEM-EDS imaging, XPS, FT-IR-ATR, Raman spectroscopy, CHNS-(O) elemental analysis, and Methyl orange (MO) adsorption studies. The specific surface area (SSA) and total pore volume increased from 642m2/g to 1237m2/g, total pore volume increased from 0.29cm3/g to 0.97cm3/g, and the mean pore diameter increased from 1.9 nm to 3.2 nm by increasing the impregnation ratio from 30 wt.% to 150 wt.%. The pH(pzc) of MC-ACs exhibited an acidic character, owing to the presence of oxygen-containing functional groups such as hydroxyl, carboxyl, metaphosphate (-PO3-), phosphates, and pyrophosphate groups, as indicated by XPS and FT-IR analysis. At a room temperature of 22 °C and an ideal pH of 2.06, the maximum adsorption capacity (qmax) rose from 46.02±4.63 mg g-1 to 326.54±37.67 mg g-1 as the impregnation ratio increased from 30 wt.% to 150 wt.%. Freundlich isotherm well explained the adsorption equilibrium at 22 °C for all MC-ACs. The effect of temperature illustrates that the adsorption of MO onto MC-AC30 % was endothermic, while the adsorption of MO onto MC-AC150 % was an exothermic. The kinetic study was conducted at 22 °C, when the equilibrium time was at 4hours, and it was a pseudo-second order (PSO) model.

Cross-Linked Starch as Media for Crystal Violet Elimination from Water: Modeling Batch Adsorption with Fuzzy Regression.

A scalable and cost-effective solution for removing pollutants from water is to use biodegradable and eco-friendly sorbents that are readily available such as starch. The current research explored the removal of crystal violet (CV) dye from water using chemically modified potato starch. The adsorbent was prepared by cross-linking potato starch with sodium trimetaphosphate (STMP). The impact of various operating factors including pH, temperature, contact time, initial CV concentration, and adsorbent dosage on the removal of CV were investigated using batch experiments. The adsorption data were analyzed using a fuzzy regression approach, which provided a range-based representation of the model's output. The cross-linked starch adsorbent was mesoporous, with a mean pore diameter of 9.8 nm and a specific surface area of 2.7 m2/g. The adsorption of CV by the STMP cross-linked potato starch was primarily influenced by the adsorbent dosage, followed by the solution pH, temperature, initial CV concentration, and contact time. The fuzzy regression model accurately predicted the independent experimental data of CV removal with an R2 of 0.985, demonstrating its value as a tool for the continuous monitoring of CV removal as well as optimizing water treatment conditions.

Elastoplastic and Electrochemical Characterization of xTiB2 Strengthened Ti Porous Composites for Their Potential Biomedical Applications

The microstructure, elastoplastic properties, and corrosive response of induced porous Ti-TiH2 materials reinforced with TiB2 particles were investigated. Samples were fabricated using CP-Ti Grade1, Titanium Hydride (TiH2), TiB2 powders (0, 3, 10, and 30 vol.%), and ammonium bicarbonate salt (40 vol.%) as a space holder. Composites were fabricated using the Powder Metallurgy technique under high-vacuum conditions (HVS) at 1100 °C. Scanning electron microscopy, X-ray diffraction, nanoindentation tests, and electrochemical assays were used to investigate the pore formation, pore distribution, phase formation, elastoplastic properties, and electrochemical behavior of the compounds, respectively. With a mean pore diameter of 50–900 µm and Young’s modulus of less than 100 GPa, which is close to the properties of human bone, the pore structures of the compounds processed here are shown to be a potential biomaterial for osseointegration. In addition, their H/Er and H3/Er2 ratios for the reinforced samples are higher than those of the unreinforced sample (1.5 and 4 times higher than the unreinforced sample, respectively), suggesting a better wear resistance of the Ti-TiH2/xTiB2 composites. Electrochemical experiments demonstrated that the Ti-TiH2/xTiB2 composites exhibited superior passivation properties compared to the Ti-TiH2 sample. Additionally, the corrosion rates exhibited by the 3 and 10 vol.% of TiB2 samples were found to be within an acceptable range for potential biomedical applications (29.26 and 185.82 E-3 mm·y−1). The elastoplastic properties combined with the electrochemical behavior place the Ti-TiH2/3-10TiB2 composites as potential candidates for the biomedical application of CP-Ti.

Purification of crude glycerol derived from biodiesel production process using ceramic membranes: Experimental studies and modeling of flux behavior

Large-scale biodiesel production generates large quantities of glycerol with high impurities levels, and new purification processes are needed to add value to this by-product of biodiesel production. Thus, this study evaluated the application of ceramic membranes for glycerol purification from biodiesel production and the influence of the mean pore diameter of the membrane, pressure, temperature, and the addition of acidified water to the mixture to be purified. The experiments were carried out in a tangential filtration module with ceramic membranes of 5 kDa, 20 kDa, 0.05 μm, and 0.2 μm, varying the pressure by 1, 2, and 3 bar and the temperature by 25, 40, and 60 °C. The results showed that increasing the pressure, average pore diameter and temperature caused an increase in the permeate flux. Furthermore, adding acidified water increased permeate fluxes and glycerol concentrations for all membranes and pressures used. A higher glycerol content (91.13 %) was obtained with the 5 kDa membrane at 3 bar and 60 °C. The traditional fouling mechanism models failed to fit most of the experimental data. On the other hand, the proposed generalized model adequately predicted the experimental permeate flux data for the different types of fouling mechanisms observed.

Controllable preparation of carbon nanofiber membranes for enhanced flexibility and permeability

The electrospinning-produced carbon nanofiber membranes (CNFM) have been applied in many fields for their three-dimensional porous networks, however, the natural fragility impedes their practical applications. Introducing plasticizers into carbon fibers has been proven an efficient way to increase the flexibility of CNFM but the extent is limited. This work explored dual plasticizers strategy to improve the flexibility of CNFM. The addition of zinc acetate and tetraethyl orthosilicate leads to bigger carbon nanofibers and higher mean pore diameters. They can be transformed into SiO2 and ZnO nanoparticles that embed in the carbon fibers, and act as plasticizers to inhibit stress diffusion. The Young's modulus of the optimal SZCNFM-2.0-1.5-700 is 31.0 MPa, which is lower than single plasticizer can reduce. The mechanism of dual plasticizers collaboratively improving the flexibility of SZCNFM was proved based on the characterization results. The SZCNFM-2.0-1.5-700 with well flexibility also revealed high permeability, for instance, the gravity-induced cyclohexane flux is 486.67 L m−2 h−1. Furthermore, the SZCNFM-2.0-1.5-700 requires only half the time compared to the commercial filter membrane when separating the same amount of Pd@CN suspension in the suction filter.

A phosphate glass reinforced composite acrylamide gradient scaffold for osteochondral interface regeneration

The bone-cartilage interface is defined by a unique arrangement of cells and tissue matrix. Injury to the interface can contribute to the development of arthritic joint disease. Attempts to repair osteochondral damage through clinical trials have generated mixed outcomes. Tissue engineering offers the potential of integrated scaffold design with multiregional architecture to assist in tissue regeneration, such as the bone-cartilage interface. Challenges remain in joining distinct materials in a single scaffold mass while maintaining integrity and avoiding delamination. The aim of the current work is to examine the possibility of joining two closely related acrylamide derivatives such as, poly n-isopropyl acrylamide (pNIPAM) and poly n‑tert‑butyl acrylamide (pNTBAM). The target is to produce a single scaffold unit with distinct architectural regions in the favour of regenerating the osteochondral interface. Longitudinal phosphate glass fibres (PGFs) with the formula 50P2O5.30CaO.20Na2O were incorporated to provide additional bioactivity by degradation to release ions such as calcium and phosphate which are considered valuable to assist the mineralization process. Polymers were prepared via atom transfer radical polymerization (ATRP) and solutions cast to ensure the integration of polymers chains. Scaffold was characterized using scanning electron microscope (SEM) and Fourier transform infra-red (FTIR) techniques. The PGF mass degradation pattern was inspected using micro computed tomography (µCT). Biological assessment of primary human osteoblasts (hOBs) and primary human chondrocytes (hCHs) upon scaffolds was performed using alizarin red and colorimetric calcium assay for mineralization assessment; alcian blue staining and dimethyl-methylene blue (DMMB) assay for glycosaminoglycans (GAGs); immunostaining and enzyme-linked immunosorbent assay (ELISA) to detect functional proteins expression by cells such as collagen I, II, and annexin A2. FTIR analysis revealed an intact unit with gradual transformation from pNIPAM to pNTBAM. SEM images showed three distinct architectural regions with mean pore diameter of 54.5 µm (pNIPAM), 16.5 µm (pNTBAM) and 118 µm at the mixed interface. Osteogenic and mineralization potential by cells was observed upon the entire scaffold's regions. Chondrogenic activity was relevant on the pNTBAM side of the scaffold only with minimal evidence in the pNIPAM region. PGFs increased mineralization potential of both hOBs and hCHs, evidenced by elevated collagens I, X, and annexin A2 with reduction of collagen II in PGFs scaffolds. In conclusion, pNIPAM and pNTBAM integration created a multiregional scaffold with distinct architectural regions. Differential chondrogenic, osteogenic, and mineralized cell performance, in addition to the impact of PGF, suggests a potential role for phosphate glass-incorporated, acrylamide-derivative scaffolds in osteochondral interface regeneration.

Structural modification of CNT-C xerogel through synthesis parameters

This study focuses on the synthesis of porous carbonaceous structures by drying resorcinol-formaldehyde (RF) gels under ambient conditions and then carbonizing them in an inert atmosphere. This avoids the expensive drying processes like supercritical drying or freeze drying. However, drying under ambient conditions does cause structural shrinkage and a reduction in porosity and specific surface area. Therefore, the goal of this study was to compensate for these structural degradations by adjusting other synthesis and process parameters, such as solvent exchange, drying condition, content of water, catalyst, and CNT in the gel. In the present study, different organic solvents such as t-butanol, ethanol, and acetone were used to replace the water in the hydrogels at a certain R/F molar ratio (1:2). The experimental results showed that t-butanol, with its low surface tension, resulted in a structure with a high specific surface area and pore volume. Regarding the catalyst dosage, by changing the R/C molar ratio between 71 and 849, the best structural properties were obtained using R/C∼200. Increasing the water content from 15 to 30 mL led to a decrease in specific surface area and pore volume. Drying the gel at an oven temperature of 85 °C resulted in the highest specific surface area, pore volume, and mean pore diameter. Increasing the dosage of carbon nanotubes (CNTs) in the range of 20–150 mg led to an increase in total pore volume and mean pore diameter. The results of this work can be a step forward towards the industrialization of these materials in various applications.

A comparative study on bath and horn ultrasound‐assisted modification of bentonite and their effects on the bleaching efficiency of soybean and sunflower oil: Machine learning as a new approach for mathematical modeling

AbstractIn this study, the effect of high‐power bath and horn ultrasound at different powers on specific surface area (SBET), total pore volume (Vtotal), and average pore volume (Dave) of bleaching clay was examined. After subjecting the bleaching clay to ultrasonication treatment, the SBET values demonstrated an escalation from 31.4 ± 2.7 m2 g−1 to 59.8 ± 3.1 m2 g−1 for HU200BC, 143.8 ± 3.9 m2 g−1 for HU400BC, 54.4 ± 3.6 m2 g−1 for BU400BC, and 137.5 ± 2.8 m2 g−1 for BU800BC. The mean pore diameter (Dave) declined from 29.7 ± 0.14 nm in bleaching clay to 11.3 ± 0.13 nm in HU200BC, 8.3 ± 0.12 nm in HU400BC, 16.7 ± 0.14 nm in BU400BC, and 9.6 ± 0.12 nm in BU800BC. Therefore, horn ultrasound‐treated bleaching clay significantly increased SBET and Vtotal, indicating improved adsorption capacity. Moreover, to establish the relationship between bleaching parameters, seven multi‐output ML regression models of Feedforward Neural Network (FNN), Random Forest (RF), Support Vector Regression (SVR), Multi‐Task Lasso, Ridge regression, Extreme Gradient Boosting (XGBoost), and Gradient Boosting are used, and compared with response surface methodology (RSM). ML has revolutionized the understanding of complex relationships between ultrasonic parameters, oil color, and pigment degradation, providing insights into how various factors such as temperature, ultrasonic power, and time can influence the bleaching process, ultimately enhancing the efficiency and precision of the treatment. The XGBoost model showed outstanding performance in predicting the target variables with a high R2‐train up to 1, R2‐test up to .983, and a minimum mean absolute error (MAE) of 0.498. The lower error between the predicted and experimental values implies the superiority of the XGBoost model to predict outcomes rather than RSM. It represents the suitability of bath ultrasound as a mild condition for low‐pigmented oil bleaching. Finally, the Bayesian optimization method in conjunction with XGBoost was used to optimize the amount of bleaching clay and energy consumption, and its performance was compared with RSM. It was observed that the consumption of bleaching clay was reduced by approximately 60% for sunflower oil and 30%–35% for soybean oil.

Hierarchical mesoporous TiO2/starch-based microparticles used as an efficient and reusable adsorbent for removal of water-soluble dye

The widespread use of organic dyes in various industrial applications, driven by rapid industrialization, has become a significant environmental concern. Thus, highly efficient and reusable adsorbent for removal of pollutant dyes have gained increasing attention in water treatment. In this study, we present TiO2 nanoparticle-embedded mesoporous starch-based microparticle (TiO2@MSMP) with hierarchical rose-like structure were synthesis by using acetone precipitation of short-chain glucan (SCG) obtained from waxy maize starch. The resulting TiO2@MSMP exhibits an A-type crystalline polymorph and mean particle size of approximately 2 μm, displaying a type IV adsorption isotherm with a mean pore diameter of 19 nm and an average surface area of 12.34 m2/g. The adsorption ability of TiO2@MSMP towards methyl orange (MO) and crystal violet (CV) were 85.8 mg/g and 103.8 mg/g, respectively. The reusability of TiO2@MSMP was achieved by UV irradiation, which resulted in photodegradation of the adsorbed dye over 80 % while maintaining good absorption ability and structural stability during the recycling process. Given its cost-effectiveness, high adsorption capacity, and excellent reusability, TiO2@MSMP holds promise as an effective and environmentally friendly adsorbent with significant potential for removing dyes from aqueous solutions and purifying water.

Removal of lead ions onto potassium-type fine-grained zeolite prepared from dry or wet milling treatment

Potassium-type zeolite (KZ) was prepared from coal fly ash by hydrothermal activation treatment using potassium hydroxide solution and potassium-type fine-grained zeolite was prepared by dry milling (KZ-D) or wet milling (KZ-W). The effects of the different treatments on the Pb2+ adsorption performance were assessed. KZ-W resulted in a much smaller particle diameter (0.61 ± 0.12 µm) than KZ-D (1.4 ± 0.48 µm) and KZ (6.5 ± 0.49 µm). KZ-W also realized a higher pore volume, mean pore diameter, and specific surface area, than KZ-D and KZ. Additionally, KZ-W realized a greater Pb2+ adsorption capacity (242.6 mg/g) than KZ (195.3 mg/g) or KZ-D (188.9 mg/g). The adsorption phenomena were fitted to the Freundlich and Langmuir models to clarify the Pb2+ adsorption mechanism, and then both models showed a good fit to the experimental data (the correlation coefficients of 0.914–0.996 for Freundlich model and 0.897–0.981 for Langmuir model). Additionally, the ion exchange capability, elemental distribution, and binding energy before and after adsorption were analyzed. The results indicated that the physicochemical characteristics of the tested adsorbent surface affected the Pb2+ adsorption capacity in the aqueous phase. According to kinetics, the pseudo-second-order model matched the experimental data (the correlation coefficients of 0.996–0.999). The samples also demonstrated selective adsorption of Pb2+ in a binary solution. The results demonstrated that KZ-W can effectively remove Pb2+ from the aqueous phase and that it may be a useful tool for preventing contamination of water bodies.

Leachate treatment via electrocoagulation–coal‐based powdered activated carbon process: Efficiencies, mechanisms, kinetics, and costs

AbstractThis study aims to improve COD, NH3‐N, and turbidity removal from Bingöl's leachate using a single‐reactor integrated electrocoagulation (EC)–coal‐based powdered activated carbon (CBPAC) process under various experimental conditions. In the EC‐CBPAC process, three stainless‐steel cathodes and three aluminum electrodes were connected to the negative and positive terminals of the power supply, respectively. The initial concentrations in the leachate were 1044 mg O2/L for COD, 204 mg/L for NH3‐N, and 57 NTU (or 71.25‐mg (NH2)2H2SO4/L) for turbidity, respectively. After a 40‐min EC‐CBPAC process, with a CBPAC dosage of 5 g/L and pH of 5 for COD and turbidity, and 9.5 for NH3‐N, the optimum removal efficiencies for COD, NH3‐N, and turbidity were achieved at 92%, 40%, and 91%, respectively. When the EC process was applied without CBPAC under the same experimental conditions, the removal efficiencies of COD, NH3‐N, and turbidity were 87%, 28%, and 54%, respectively. Before and after the EC‐CBPAC process, the Brunauer–Emmett–Teller (BET) surface area, pore volume, and mean pore diameter of the CBPAC were found to be (888 m2/g, 0.498 cm3/g, and 22.28 Å) and (173 m2/g, 0.18 cm3/g, and 42.8 Å), respectively. The optimum pseudo‐first‐order (PFO) rate constants for COD, turbidity, and NH3‐N were determined to be 3.15 × 10−2, 4.77 × 10−2, and 8.8 × 10−3 min−1, respectively. With the current density increasing from 15 to 25 mA/cm2, energy consumption, unit energy consumption, and total cost increased from 68.7 to 122.4 kWh/m3, 6.948 to 15.226 kWh/kg COD, and 0.85 to 1.838 $/kg COD, respectively.Practitioner points EC‐CBPAC process has greater COD, NH3‐N, and turbidity removal efficiency than EC process. COD and turbidity achieved their optimum disposal efficiencies at 92% and 91%, respectively, at pH 5 The most efficient disposal efficiency for NH3‐N was observed to be 40% at pH 9.5. EC‐CBPAC process increased removal efficiencies for COD, NH3‐N, and turbidity by 20%, 19%, and 38%, respectively, compared with EC alone. The turbidity, NH3‐N, and COD disposal fitted PSO model due to high correlation values (R2 0.94–0.99).

High-performance hydrophobic aerogel based on nanocellulose, graphene oxide, polyvinyl alcohol, and hexadecyltrimethoxysilane: Structure, properties, and applicability

The most prevalent kinds of contaminants found in water sources are oil and organic substances, which are often present in either spilled or emulsified states. Due to the vast surface area and porous structure, nanocellulose aerogel is an environmentally benign material widely employed for its efficacy in adsorbing oils and organic pollutants. In this study, an aerogel composed of nanocellulose (CNF), graphene oxide (GO), and polyvinyl alcohol (PVA), subsequently modified with hexadecyltrimethoxysilane (HDTMS), exhibited a well-defined structure and demonstrated proficient removal of waste oil and certain organic solvents from water at high speed. By a simple and cheap preparation method from solution mixing and freeze-drying, the resultant aerogel has a high porosity of 97.26 %, a light density of 0.0036 g/cm3, a mesoporous structure with a mean pore diameter of 3.5 nm, and a surface area of 15.717 m2/g. Aerogel exhibits pronounced superhydrophobic behavior, achieving a contact angle of up to 152°, thereby substantially impeding water permeation through its structure in experimental assessments of selectivity and efficacy in separating oil-water mixtures. According to Langmuir isotherm model, DO adsorption occurred in a monolayer. CNF/GO/PVA/HDTMS aerogel exhibited a maximum adsorption capacity of 322.58 mg/g, with the pseudo-second-order model effectively representing this adsorption process. Furthermore, the CNF/GO/PVA/HDTMS aerogel displays a strong adsorption capability towards oils and organic solvents, with a range of 10–25 times the original volume of the aerogel. Another feature of the resultant aerogel is its good deemulsion ability on both water-in-oil and oil-in-water emulsions. The pump extraction method is more effective than the extraction method in oil recovery and reuse of the aerogel. The results obtained in the study show a potential environmentally friendly material for the treatment of oily and organic solvent wastewater from industries.

Membrane role in heat and mass transfer resistance distribution and performance of hollow fiber membrane contactor for SGMD desalination

Hollow fiber membrane contactor (HFMC) is the core device of heat mass exchange between seawater solution and sweeping air in sweeping gas membrane distillation (SGMD) desalination. In order to reveal the distribution of heat and mass transfer resistance on feed solution side, porous membrane side and sweeping air side, a mathematical model considering the simultaneous heat mass transfer and water vapor diffusion mechanism in the membrane pores was established for the cross-flow HFMC. The simulation results of the model were compared with experimental results and literature results. Comparison shows that the deviation of simulation results of the model is less than 13.4 %, which verifies the accuracy and reliability of the simulation results. Influences of the main structural characteristics of porous membrane on the resistance distribution of heat and mass transfer, efficiency and membrane flux were explored. Air side dominates the heat transfer process, while the membrane side accounts for less than 39 % of the total heat transfer resistance for the main range of membrane microstructure parameters investigated. The mass transfer is controlled by the porous membrane except for thin membrane with a thickness of less than 100 μm. Membranes with porosity above 0.8 and as thin as possible can achieve better mass transfer efficiency and freshwater flux. Increasing mean pore diameter has a strong promotion effect on the increase of membrane flux before it reaches 150 nm, and beyond this critical value, the water vapor diffusion mechanism changes from Knudsen collision to molecular collision. Effects of different operating parameters and membrane microstructure parameters on air temperature distribution and humidity distribution were also analyzed.

Encapsulation of Lactiplantibacillus plantarum CRD7 in sub-micron pullulan fibres by spray drying: Maximizing viability with prebiotic and thermal protectants

Pullulan was used as the wall material for microencapsulation of L. plantarum CRD7 by spray drying, while isomalto-oligosaccharides (IMO) was used as prebiotic. Also, the effect of different thermal protectants on survival rate during microencapsulation was evaluated. Taguchi orthogonal array design showed that pullulan at 14 % concentration, IMO at 30 % concentration and whey protein isolate at 20 % rate were the optimized wall material, prebiotic and thermal protectant, respectively for microencapsulation of L. plantarum. FESEM images revealed that the spray-dried encapsulates were fibrous similar to those produce by electrospinning, while fluorescence microscopy ascertained that most of the probiotic cells were alive and intact after microencapsulation. The adsorption-desorption isotherm was of Type II and the encapsulate had specific surface area of 1.92 m2/g and mean pore diameter of 15.12 nm. The typical amide II and III bands of the bacterial proteins were absent in the FTIR spectra, suggestive of adequate encapsulation. DSC thermogram showed shifting of melting peaks to wider temperature range due to interactions between the probiotic and wall materials. IMO at 30 % (w/w) along with WPI at 20 % concentration provided the highest storage stability and the lowest rate of cell death of L. plantarum after microencapsulation. Acid and bile salt tolerance results confirmed that microencapsulated L. plantarum could sustain the harsh GI conditions with >7.5 log CFU/g viability. After microencapsulation, L. plantarum also possessed the ability to ferment milk into curd with pH of 4.62.