Combining Polyvinyl Alcohol Research Articles

Physiochemical and In-Vitro Bioactivity Characterization of Polyvinyl Alcohol / Halloysite Nanotube / Collagen (PVA/HNT/Col) using Freeze-Thawing Method and Spin Coated Technique for Wound Healing Applications

Hydrogels are still relevant instruments that can support and improve the dynamic biological process of wound healing. This paper modified hydrogel film by combining polyvinyl alcohol (PVA), halloysite nanotube (HNT), and collagen using simple freeze-thawing and spin-coating techniques. The modification aims to improve the physiochemical and in-vitro bioactivity of the PVA/HNT hydrogel films via the inclusion of different concentrations of collagen. 0.092 mm PVA/HNT/Col3 hydrogel film was suggested to have excellent morphological properties with 94.11 % porosity. It also has good tensile properties with excellent hydrophilicity performance at 38.40o contact angle and 83.528% swelling capacity compared to other modified films. In-vitro bioactivity suggested that the PVA/HNT/Col3 are safe and non-toxic toward host tissue and can promote healing at 93.12% wound closure after 24 hours of treatment. Hence, this material displays huge potential as a wound healing matrix template.

Evaluation of the Mechanical Strength and Cell Adhesion Capacity of POSS Doped PVA/CMC Hernia Patch.

Peritoneal adhesion typically occurs in applications such as abdominal, pelvic, and vascular surgery. It is necessary to develop a mechanical barrier to prevent adhesion. In this study, a novel biomaterial as a mechanical barrier is developed by combining polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC), doped with polyhedral oligomeric silsesquioxane (POSS) to prevent peritoneal adhesion. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods reveal that POSS nanoparticles in the PVA matrix disrupted the intramolecular hydroxyl groups and structure of the crystal region. Electron microscopy (EM) images reveal that high concentrations of POSS (2wt.%) cause irregular clustering in the composite matrix. As the concentration of POSS increases in the matrix, the degradation of the membranes increases, and protein adhesion decreases. In vitro cytotoxicity tests show a toxic effect on cells for PVA/CMC composite membranes, while on the other hand, the addition of POSS increases cell viability. According to the MMT test the POSS decreases cell adhesion of membranes. When comparing the POSS doped membrane to the undoped PVA/CMC membrane, an increase in the total antioxidant level and a decrease in the total oxidant level is observed.

Magnetic‐Driven Hydrogel Spiral PVA/Fe3O4 Micromotors for Targeted Photothermal Therapy

AbstractPhototherapy has emerged as a promising technique for cancer treatment, offering high efficiency and minimal side effects. Nevertheless, conventional phototherapy agents suffer from low targetability and inefficient delivery. Here, a novel approach is proposed using helical hydrogel motors fabricated by combining polyvinyl alcohol, melamine, water, and Fe3O4 nanoparticles. These magnetic motors are capable of precise therapy on tumor cells driven by an external magnetic field. By converting light into heat upon near‐infrared illumination, the motors elevate the temperature of the targeted region, resulting in a significant therapeutic effect, with over 60% eradication of HeLa cells achieve under 808 nm near‐ infrared light (1.5 W cm−2). These helical micromotors exhibit excellent movement performance and biocompatibility, facilitating their in vivo applications and contributing to the advancement of biomedicine.

Strength and thermal insulation properties of foam-formed ceramic fiber paper with different reinforcement methods

Abstract Foam-forming technique imparts ceramic fiber paper with excellent uniformity, low density, and high porosity, but its strength loss must be compensated. Herein, a flexible and rigid foam-formed ceramic fiber network was manufactured by using different strength improvement methods and simultaneously investigated their strength and thermal insulation properties. Sufficient strength (1136 kPa) was achieved by combining Polyvinyl alcohol (PVA) 2 % and Polyester (PET) 3 %. However, the tensile strength of fiber networks would decrease under the contribution of inter-fiber bonding area reduced when the fiber length was longer than 24 mm. Benefiting from the developed flocculation system (aluminum sol-anionic polyacrylamide-carboxymethylcellulose), the strength of the foam-formed ceramic fiber network was 20 kPa, the retention rate increased from 75 % to 88 %, and the average aggregation factor of fillers in the Z direction was 0.67. By adjusting the ratio and Z-directional distribution of functional fillers, the sintered foam-formed paper with a tensile strength of 1300 kPa and compressive strength of 1000 kPa could be obtained. The thermal insulation performance (thermal conductivity 0.03252 W/(m·K)) was similar to the quartz fiber paper reinforced silica airgel, and the flame resistance was better than the commercialized aluminum silicate wool board.

A novel Ductile Lightweight Fiber-Reinforced Concrete (DLFC) infill for seismic-prone zones: Experimental and numerical investigations

In urban construction, reinforced concrete (RC) with masonry infill predominates, though traditional masonry's brittle nature poses significant seismic vulnerabilities. This study introduces a novel approach using Ductile Lightweight Fiber-Reinforced Concrete (DLFC) as an infill to address these challenges. Composed of cement, water, expanded polystyrene (EPS), ultra-fine filler, and combined polyvinyl alcohol (PVA) and polypropylene (PPF) fibers, DLFC aims to enhance ductility, minimize damage, and amplify energy absorption in seismic events. Three RC frames, with height-to-span ratios of 0.77, 1.00, and 1.28, were designed and experimentally tested under simultaneous vertical and lateral cyclic loading to evaluate DLFC's seismic response. Results illustrated that DLFC-infilled RC frames boast impressive ductility, an 8% drift at complete failure, minimal out-of-plane behavior, and elevated damping ratios. Remarkably, DLFC's low in-plane stiffness led to reduced frame stiffness compared to traditional masonry. An empirical equation, closely aligning with experimental outcomes, was formulated to estimate the lateral strength of the infill wall, and a comparison with the bare frame was made, though it necessitates additional validation through further testing.

Interface synergistic stabilization of zinc anodes via polyacrylic acid doped polyvinyl alcohol ultra-thin coating

Aqueous batteries have been considered as an alternative to lithium-ion batteries due to their advantages such as high energy density and high safety. Aqueous zinc ion batteries (ZIBs) have attracted particular attention due to the high capacity, low cost and low redox potential of zinc metal. However, zinc metal anodes suffer from problems such as dendrite growth, hydrogen evolution reaction (HER), and surface corrosion, which can lead to unfavorable effects, including reduced battery capacity and shorter cycle life. Herein, we constructed a PVA@PAA protective layer on the zinc anode surface by combining polyvinyl alcohol (PVA) with polyacrylic acid (PAA). This protective layer not only physically inhibits the growth of dendrites but also suppresses HER and surface corrosion via isolation of the electrolyte from the zinc anode. Furthermore, theoretical calculations indicate that PAA enhances the reactivity of PVA, increasing zinc ion transport rates and improving ionic conductivity. With the above synergistic effects, the symmetric batteries could achieve an ultra-long stable cycling of 2400 h at 3 mA·cm−2. Furthermore, this research lays the technical groundwork for the expanded applications of ZIBs on a larger scale.

A mussel inspired polyvinyl alcohol/collagen/tannic acid bioadhesive for wet adhesion and hemostasis

Bioadhesives are useful in surgery for hemostasis, tissue sealing and wound healing. However, most bioadhesives have limitations such as weak adhesion in wet conditions, insufficient sealing and poor clotting performance. Inspired by the adhesion mechanism of marine mussels, a novel bioadhesive (PCT) was developed by simply combining polyvinyl alcohol (PVA), collagen (COL) and tannic acid (TA) together. The results showed that the adhesion, sealing and blood coagulation properties boosted with the increase of tannic acid content in PCT. The wet shear adhesion strength of PCT-5 (the weight ratio of PVA:COL:TA=1:1:5) was 60.8 ± 0.6 kPa, the burst pressure was 213.7 ± 0.7 mmHg, and the blood clotting index was 39.3% ± 0.6%, respectively. In rat heart hemostasis tests, PCT-5 stopped bleeding in 23.7 ± 3.2 s and reduced bleeding loss to 83.0 ± 19.1 mg, which outperformed the benchmarks of commercial gauze (53.3 ± 8.7 s and 483.0 ± 15.0 mg) and 3 M adhesive (Type No.1469SB, 35.3 ± 5.0 s and 264.0 ± 14.2 mg). The as-prepared bioadhesive could provide significant benefits for tissue sealing and hemorrhage control along its low cost and facile preparation process.

Biomass Photothermal Hydrogel Based on Tea Leaves Residue for Cogeneration of Clean Water and Electricity

AbstractInterfacial solar‐driven evaporation has attracted much attention due to its high photothermal conversion efficiency. The core technology of photothermal conversion is photothermal materials, biomass photothermal materials are characterized by low cost, large specific surface area, environmental friendliness, and renewability. Discarded tea leaf residue (TLR) is harmful to the environment and has good recycling potential. In this work, a high‐performance, low‐cost, environmentally friendly solar steam generation material is fabricated by combining polyvinyl alcohol hydrogels and biomass photothermal material TLR. TheTLR hydrogel utilizes solar energy as a renewable energy source for desalination. Under 1.0 kW m−2 simulated solar irradiation, the evaporation rate is 1.35 kg m−2 h−1 and the evaporation efficiency is 93.35%. The waste heat generated during solar water evaporation can be effectively used for synergistic water‐electricity cogeneration, thus achieving an evaporation rate and voltage of 0.91 kg m−2 h−1 and 58.8 mV under 1.0 kW m−2 solar irradiation, respectively. The prepared hydrogel can also be used as a good organic dye adsorbent material, which has a broad application prospect in wastewater treatment. This method for preparing solar absorbers reduces manufacturing costs environmentally friendly and guides the potential practical application using discarded waste.

A biomass hydrogel solar evaporator based on low-grade tobacco leaves for water evaporation and thermoelectric conversion applications

A low-cost and eco-friendly solar steam generator was designed by combining polyvinyl alcohol hydrogels with low-grade tobacco leaves biomass photothermal materials, which apply for water evaporation and thermoelectric conversion.

Highly elastic, frost-resistant and antimicrobial flexible sensor inspired by ramen noodles for human motion detection and deep learning of handwritten content

Biomaterial-based hydrogels have gained significant attention in the development of flexible multifunctional electronic devices for the future. However, it is a great challenge to prepare biomaterial-based hydrogels with high toughness, electrical conductivity and frost-resistant by a simple and low-cost way. Meanwhile, starch bio-based hydrogels have emerged as a popular area of research due to their abundant sources and degradability. Unfortunately, these hydrogels often exhibit poor mechanical properties and freeze resistance, which restrict their practical applications. Taking inspiration from the traditional food ramen, where a simple mixture of noodles can become remarkably stretchable and resilient, our study aims to enhance the performance of hydrogels by leveraging their toughening mechanism. We achieve this by combining polyvinyl alcohol (PVA), branched chain starch (Amy), wheat protein (WP), ethylene glycol (EG) with saline. The Amy/PVA/EG/WP/S (APEWS) organohydrogels demonstrated excellent mechanical properties (1.12 MPa) due to the combination of PVA as a hard backbone, a rich protein network, diverse functional groups, and saline components. Additionally, the binary solvent consisting of water and EG allowed the hydrogel to function effectively even at low temperatures (-20 °C). The APEWS organohydrogel exhibited promising sensing capability (GF = 1.46) and sensing stability (>500 times) as a human wearable strain sensor, making it suitable for detecting human motion and the hydrogel showed excellent antimicrobial properties against Escherichia coli (Gram-negative bacteria). Furthermore, we employed a Long Short-Term Memory (LSTM) artificial neural network for deep learning-based recognition of written content. The network achieved an accuracy of over 95.5% for different English letters and 100% for symbols. These results highlight the potential of this technology in applications such as writing sensing and information encryption. In conclusion, with the simple preparation method and low cost, APEWS organohydrogels are expected to be the next generation of green and sustainable bio-based strain sensors.

Catechol-Modified and MnO2-Nanozyme-Reinforced Hydrogel with Improved Antioxidant and Antibacterial Capacity for Periodontitis Treatment.

Periodontitis is an inflammatory disease characterized by tooth loss and alveolar bone resorption. Bacteria are the original cause of periodontitis, and excess reactive oxygen species (ROS) encourage and intensify inflammation. In this study, a mussel-inspired and MnO2 NPs-reinforced adhesive hydrogel capable of alleviating periodontitis with improved antibacterial and antioxidant abilities was developed. The hydrogel was created by combining polyvinyl alcohol (PVA), 3,4-dihydroxy-d-phenylalanine (DOPA), and MnO2 nanoparticles (NPs) (named PDMO hydrogel). The hydrogel was demonstrated to be able to scavenge various free radicals (including total ROS─O2•- and OH•) and relieve the hypoxia in an inflammatory microenvironment by scavenging excess ROS and generating O2 due to its superoxide dismutase (SOD)/catalase (CAT)-like activity. Besides, under 808 nm near-infrared (NIR) light, the photothermal performance of the PDMO hydrogel displayed favorable antibacterial and antibiofilm effects toward Escherichia coli, Staphylococcus aureus, and Porphyromonas gingivalis (up to nearly 100% antibacterial rate). Furthermore, the PDMO hydrogel exhibited favorable therapeutic efficacy in alleviating gingivitis in Sprague-Dawley rats, even comparable to or better than the commercial PERIO. In addition, in the periodontitis models, the PDMO2 group showed the height of the residual alveolar bone and the smallest shadow area of low density among other groups, indicating the positive role of the PDMO2 hydrogel in bone regeneration. Finally, the biosafety of the PDMO hydrogel was comprehensively investigated, and the hydrogel was demonstrated to have good biocompatibility. Therefore, the developed PDMO hydrogel provided an effective solution to resolve biofilm recolonization and oxidative stress in periodontitis and could be a superior candidate for local drug delivery system in the clinical management of periodontitis with great potential for future clinical translation.

An Optimization Study for the Electrospun Borate Ester Nanofibers as Light‐Weight, Flexible, and Affordable Neutron Shields for Personal Protection

AbstractIn this manuscript, a borate ester solution, as a precursor, is prepared by combining polyvinyl alcohol (PVA) and boric acid (BA). The precursor is then electrospun to form nanofibers. However, the addition of BA has a negative effect on the spinning behavior by changing the conductivity. The solution's quality is enhanced through use of additives such as glycerol, sodium chloride, and acetic acid. The effect of additives on the viscosity and conductivity of solutions, and their spinning behavior, is investigated. By adjusting electrospinning process variables and solution properties, nanofibers are produced. Fourier transform infrared (FT‐IR) analysis is performed to identify the formation of borate ester as a result of the reaction between PVA and BA. Thermal analysis is used to characterize the thermal stability of the fibers. Scanning electron microscopy (SEM) is used to examine the fiber morphology and diameter distribution. The findings are used to determine the best viscosity–conductivity windows for the production of electrospun borate ester nanofibers. Finally, the ability of optimized nanofibers to capture neutrons is evaluated using an Am‐Be neutron source and a BF3 detector set up. The results of the measurements indicate that the incorporation of BA into PVA nanofibers can enhance their neutron shielding capabilities up to 7.3%.

A Delayed Cross‐Linking Strategy for Evolvable Hydrogels

AbstractBiological tissues grow or evolve through a series of complicated processes of matter and energy internalization, which are highly challenging to mimic in synthetic materials. Herein, a delayed cross‐linking strategy is developed to program the reactivity of cross‐linking sites and make hydrogels evolvable. The polymer networks are constructed by combining polyvinyl alcohol (PVA) with a polyzwitterion comprising both cationic quaternary ammonium and anionic phenylboronic acid groups (PQBA). Shielding of phenylboronic acid groups in ion pairs and polyzwitterion microdomains delays the cross‐linking between PVA and PQBA. Mechanical stimulations unlock the phenylboronic acid groups and dramatically accelerate the cross‐linking reaction. A simple stretching treatment makes the hydrogels stronger. Training the hydrogels with five cycles of 200% stretching results in up to ≈13.0‐ and ≈22.8‐fold of enhancements in tensile strength and maximum Young's modulus, respectively. The hydrogels can also self‐evolve in a damage‐healing process, the fracture strength and maximum Young's modulus of the hydrogels increase by at most ≈7.5‐ and ≈27.2‐fold after five times of repeated tensile rupture and self‐healing. The study demonstrates the possibility of designing “living polymeric materials” by programming the cross‐linking kinetics of polymer networks.

Ultrasound flow phantom for transcranial Doppler: An assessment of angular mismatch effect on blood velocity measurement in comparison to optical particle image velocimetry

Detecting abnormal blood flow is possible through transcranial Doppler (TCD) ultrasound by measuring blood velocity in cerebral arteries. Velocity measurements are at the highest precision when the direction of blood flow coincides with the ultrasound beam. However, because TCD is typically performed blindly (i.e., without a B-mode), a 0° interrogation angle is usually assumed. This leads to a common issue of angular mismatch. This study quantitatively shows the angular mismatch effects on the measured velocities using a TCD ultrasound flow phantom compared with the velocities measured by optical particle image velocimetry (PIV) as control. Resulting errors with and without ultrasound machine angular correction were also considered. An ultrasound phantom developed by combining polyvinyl alcohol hydrogel (PVA-H), quartz glass as a scatterer, and a gypsum plate as a skull bone was utilized to approximate the middle cerebral artery TCD measurement from the temporal window. The PVA-H and quartz glass compositions were controlled to achieve transparency and enable PIV velocity measurement. Then, TCD velocity measurement was conducted on several interrogation and mismatch angles. Comparison results revealed that without an ultrasound machine angle correction, all measurements yielded underestimation with 73.9% at the highest in the 80° interrogation window at the 130 mL/min flow. On the other hand, with the correction, the errors in almost all angles were comparatively lower; however, at 80° at the 124 mL/min flow, a maximum overestimation rate of 113.7% was found, showing a larger error magnitude. Therefore, we find that angular mismatch, especially in larger angles, leads to inaccurate velocity measurements in TCD. Our results suggest that despite angle correction, velocity errors may still occur when the interrogation angle changes.

Embolic Agent Choice in Middle Meningeal Artery Embolization as Primary or Adjunct Treatment for Chronic Subdural Hematoma: A Systematic Review and Meta-analysis.

Middle meningeal artery embolization is an emerging treatment option for chronic subdural hematomas. Our aim was to assess outcomes following middle meningeal artery embolization by different techniques, including in comparison with traditional surgical methods. We searched the literature databases from inception to March 2022. We selected studies reporting outcomes after middle meningeal artery embolization as a primary or adjunctive treatment for chronic subdural hematoma. We analyzed the risk of recurrence of chronic subdural hematoma, reoperation for recurrence or residual hematoma, complications, and radiologic and clinical outcomes using random effects modeling. Additional analyses were performed on the basis of whether middle meningeal artery embolization was used as the primary or adjunct treatment and by embolic agent type. Twenty-two studies were included with 382 patients with middle meningeal artery embolization and 1373 surgical patients. The rate of subdural hematoma recurrence was 4.1%. Fifty (4.2%) patients underwent a reoperation for a recurrent or residual subdural hematoma. Thirty-six (2.6%) experienced postoperative complications. The rates of good radiologic and clinical outcomes were 83.1% and 73.3%, respectively. Middle meningeal artery embolization was significantly associated with decreased odds of subdural hematoma reoperation (OR = 0.48; 95% CI, 23.4-99.1; P = .047) compared with surgery. The lowest rates of subdural hematoma radiologic recurrence, reoperation, and complications were observed among patients receiving embolization with Onyx, whereas good overall clinical outcome occurred most commonly with combined polyvinyl alcohol and coils. A limitation was the retrospective design of studies included. Middle meningeal artery embolization is safe and effective, either as a primary or adjunctive treatment. Treatment using Onyx seems to yield lower rates of recurrence, rescue operation, and complications whereas particles and coils produce good overall clinical outcomes.

Preparation of a Hydrogel Nanofiber Wound Dressing.

The study addressed the production of a hydrogel nanofiber skin cover and included the fabrication of hydrogel nanofibers from a blend of polyvinyl alcohol and alginate. The resulting fibrous layer was then crosslinked with glutaraldehyde, and, after 4 h of crosslinking, although the gelling component, i.e., the alginate, crosslinked, the polyvinyl alcohol failed to do so. The experiment included the comparison of the strength and ductility of the layers before and after crosslinking. It was determined that the fibrous layer following crosslinking evinced enhanced mechanical properties, which acted to facilitate the handling of the material during its application. The subsequent testing procedure proved that the fibrous layer was not cytotoxic. The study further led to the production of a modified hydrogel nanofiber layer that combined polyvinyl alcohol with alginate and albumin. The investigation of the fibrous layers produced determined that following contact with water the polyvinyl alcohol dissolved leading to the release of the albumin accompanied by the swelling of the alginate and the formation of a hydrogel.

Growth of Human Dermal Fibroblasts on Polyvinyl Alcohol-Silk Fibroin Nanofiber Scaffold

Skin tissue engineering is a developing technology to heal severe wounds. Combining polyvinyl alcohol (PVA) and silk fibroin (SF) nanofibers is a promising method of developing a skin scaffold because the resulting structure mimics collagen fibers. The aim of this research was to study the growth of human dermal fibroblasts (HDF) on a polyvinyl alcohol-silk fibroin (PVA-SF) nanofiber scaffold that was produced by electrospinning. Morphological characterization and chemical analysis of the scaffold were performed by scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR), and contact angle measurement. The biocompatibility of the scaffold was tested by MTT cytotoxicity assay, SEM analysis, adherence ratio calculation, and analysis of the HDF growth curve for 9 days. The FTIR results confirmed the presence of SF and PVA. The average fiber diameter and pore size of the PVA scaffold were greater than those of the PVA-SF scaffold. Both scaffolds had hydrophilic properties and were not cytotoxic. Thus, HDF can attach and grow on both types of scaffold better than HDF seeded on a polystyrene plate. In conclusion, the addition of SF to the PVA nanofibers caused bead formation, which affected the substrate topography, decreased hydrophilicity and also decreased the fiber diameter and pore size in the nanofiber scaffold compared to the PVA nanofiber scaffold without SF addition. SF addition increases cell attachment to the nanofiber scaffold and has potential to facilitate HDF cell growth.

Synthesis and study of sorption properties of polyvinyl alcohol (PVA)-based hybrid materials

The present contribution aims at reporting the synthesis and the preliminary evaluation of hybrid materials combining polyvinyl alcohol (PVA) functionalized with ethylenediaminetetraacetic acid (EDTA) as complexing groups, and alumina that, together, were able to efficiently complex and remove metallic cations from aqueous effluents. For such purpose, well-defined PVA homopolymers bearing an azide (PVA-N3) or an alkyne function (PVA-alkyne) were functionalized via chemical modification by either phosphoric acid (PPVA-N3), to promote adhesion to alumina, or ethylenediaminetetraacetic acid (PVA(EDTA)-alkyne), able to efficiently complex metallic cations. Modified PVA chains were coupled by Huisgen reaction using copper catalysis (CuAAC) leading to the formation of bifunctional diblock copolymers. Then, hybrid materials were produced via the grafting of PVA-based copolymers onto alumina particles. Finally, the sorption capacity of these materials towards Co(II), Ni(II) and Sr(II) was determined to evaluate their removal efficiency. Such hybrid materials could be efficiently used in the context of nuclear effluents treatment.

Structured Polyvinyl Alcohol/Zeolite/Carbon Composites Prepared Using Supercritical Fluid Extraction Techniques as Adsorbent for Bioethanol Dehydration

Introduction. Adsorption is a purification process with a more efficient energy level than others. Adsorption performance is strongly influenced by the ability of the adsorbent to be used; therefore, the modification of the adsorbent becomes a very important key for the purification process that occurs. Methods. In this study, the preparation of composite adsorbents was carried out by combining polyvinyl alcohol (PVA), zeolite (Zeo), and activated carbon (AC) as precursors. The crosslinking process was fulfilled by adding glutaraldehyde to the precursor mixtures followed by a supercritical fluid CO2 extraction (SFE) technique to create conditions for the crosslinking process. The composites were analyzed using Braunner–Emmet–Teller (BET) surface area analysis, Fourier-transform infrared (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy with energy dispersive X-ray (SEM/EDX-mapping), while individual and composite adsorbents were evaluated for their ability in bioethanol dehydration at various initial concentrations of ethanol and temperature. Results. The BET characterization shows that composite preparation under supercritical CO2 conditions provides reasonable surface areas, which are proportional to the content of activated carbon. The crosslinking process has been described by FTIR data interpretation, showing that PVA and glutaraldehyde were properly distributed on Zeo and AC precursors. The DSC characterization results give information that PVA successfully forms hydrophilic composites within Zeo and AC. The SEM micrograph analysis shows the formation of pores on the surface and cross section in structured adsorbents. The experimental adsorption shows that an increasing amount of AC in the composites increases the capacity of water adsorption (i.e., 0.80 gram of water/gram of adsorbent for PVA/Zeo/AC = 1 : 1 : 1 at 22°C). However, the effect is not significant when the ratio of AC is less than 0.5. As expected, the lower temperature increases the adsorption capacity. Further, by using approximately 4.5 gram adsorbents composite in 30 ml of water-ethanol mixtures, high concentration of bioethanol (>99%) can be achieved at various temperatures from 22°C to 40°C and bioethanol initial concentration from 88% to 96%. Conclusion. The SFE technique provides distinguished adsorbents composite properties. Further, the new composites provide about four times better adsorption capacity than that showed in the individual adsorbents test. The addition of AC influences on increasing the capacity and adsorption kinetics value.

Enhanced biological stabilization of heavy metals in sediment using immobilized sulfate reducing bacteria beads with inner cohesive nutrient

A series of experiments were conducted for treating heavy metals contaminated sediments sampled from Xiangjiang River, which combined polyvinyl alcohol (PVA) and immobilized sulfate reducing bacteria (SRB) into beads. The sodium lactate was served as the inner cohesive nutrient. Coupling the activity of the SRB with PVA, along with the porous structure and huge specific surface area, provided a convenient channel for the transmission of matter and protected the cells against the toxicity of metals. This paper systematically investigated the stability of Cu, Zn, Pb and Cd and its mechanisms. The results revealed the performance of leaching toxicity was lower and the removal efficiencies of Cu, Zn, Pb and Cd were 76.3%, 95.6%, 100% and 91.2%, respectively. Recycling experiments showed the beads could be reused 5 times with superbly efficiency. These results were also confirmed by continuous extraction at the optimal conditions. Furthermore, X-ray diffraction (XRD) and energy-dispersive spectra (EDS) analysis indicated the heavy metals could be transformed into stable crystal texture. The stabilization of heavy metals was attributed to the carbonyl and acyl amino groups. Results presented that immobilized bacteria with inner nutrient were potentially and practically applied to multi-heavy-metal-contamination sediment.