Unique Crystallization Characteristics of Pickering High Internal Phase Emulsion Templated Porous Constructs.

To study the crystallization behavior of polymeric chains under the influence of porosity, the thermal properties of various nonporous and porous poly(ε-caprolactone) (PCL) based constructs were investigated. Porous cross-linked PCL nanocomposite constructs were fabricated utilizing in situ polymerization of CL-based surfactant-free Pickering high internal phase emulsions (HIPEs), stabilized using modified fumed silica nanoparticles (mSiNP) at a minimal concentration of 0.6 wt %. The corresponding nanocomposite constructs exhibited polyhedral pore morphology with significant pore roughness due to the presence of mSiNP. DSC thermograms of nonporous constructs illustrated diminished crystallization temperature and kinetics upon cross-linking and inclusion of mSiNP which confirmed suppressed mobility of polymer chains. Further introduction of porosity led to substantial supercooling, resulting in crystallization temperatures as low as -24 °C. Changes in the crystal structure of various nonporous and porous constructs were also studied using XRD. The crystallization behavior of porous constructs was finally evaluated using Jeziorny, Ozawa, and Mo theories under nonisothermal conditions. Significant deviation from the theoretical model, as observed in the case of porous constructs, implied a complex crystallization mechanism that eventually was not only controlled by the chain immobility due to cross-linking but also heterogeneity present in the wall thickness of the constructs. The unique melting-crystallization phenomenon observed in such constructs may further be expanded to other systems of high heat capacity for utilization as energy storage materials.

3D Printed Hierarchical Porous Poly(ε-caprolactone) Scaffolds from Pickering High Internal Phase Emulsion Templating.

In the realm of biomaterials, particularly bone tissue engineering, there has been a great increase in interest in scaffolds with hierarchical porosity and customizable multifunctionality. Recently, the three-dimensional (3D) printing of biopolymer-based inks (solutions or emulsions) has gained high popularity for fabricating tissue engineering scaffolds, which optimally satisfies the desired properties and performances. Herein, therefore, we explore the fabrication of 3D printed hierarchical porous scaffolds of poly(ε-caprolactone) (PCL) using the water-in-oil (w/o) Pickering PCL high internal phase emulsions (HIPEs) as the ink in 3D printer. The Pickering PCL HIPEs stabilized using hydrophobically modified nanoclay comprised of aqueous poly(vinyl alcohol) (PVA) as the dispersed phase. Rheological measurements suggested the shear thinning behavior of Pickering HIPEs having a dispersed droplet diameter of 3-25 µm. The pore morphology resembling the natural extracellular matrix and the mechanical properties of scaffolds were customized by tuning the emulsion composition and 3D printing parameters. In vitro biomineralization and drug release studies proved the scaffolds' potential in developing the apatite-rich bioactive interphase and controlled drug delivery, respectively. During in vitro osteoblast (MG63) growth experiments for up to 7 days, good adhesion and proliferation on PCL scaffolds confirmed their cytocompatibility, assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) analysis. This study suggests that the assembly of HIPE templates and 3D printing is a promising approach to creating hierarchical porous scaffolds potentially suitable for bone tissue engineering and can be stretched to other biopolymers as well.

Block Copolymer-Templated Au@CdSe Core-Satellite Nanostructures with Solvent-Dependent Optical Properties.

In the present work, we report the fabrication and characterization of well-defined core-satellite nanostructures. These nanostructures comprise block copolymer (BCP) micelles, containing a single gold nanoparticle (AuNP) in the core and multiple photoluminescent cadmium selenide (CdSe) quantum dots (QDs) attached to the micelle's coronal chains. The asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) BCP was employed to develop these core-satellite nanostructures in a series of P4VP-selective alcoholic solvents. The BCP micelles were first prepared in 1-propanol and subsequently mixed with AuNPs, followed by gradual addition of CdSe QDs. This method resulted in the development of spherical micelles that contained a PS/Au core and a P4VP/CdSe shell. These core-satellite nanostructures, developed in different alcoholic solvents, were further employed for the time-resolved photoluminescence analysis. It was found that solvent-selective swelling of the core-satellite nanostructures tunes the distance between the QDs and AuNPs and modulates their Förster resonance energy transfer (FRET) behavior. The average lifetime of the donor emission varied from 12.3 to 10.3 nanoseconds (ns) with the change in the P4VP-selective solvent within the core-satellite nanostructures. Furthermore, the distances between the donor and acceptor were also calculated using efficiency measurements and corresponding Förster distances. The resulting core-satellite nanostructures hold promising potential in various fields, such as photonics, optoelectronics, and sensors that utilize the FRET process.

Valorised polypropylene waste based reversible sensor for copper ion detection in blood and water.

Heavy metals and plastic pollutants are the two most disastrous challenges to the environment requiring immediate actions. In this work, a techno-commercially feasible approach to address both challenges is presented, where a waste polypropylene (PP) based reversible sensor is produced to selectively detect copper ions (Cu2+) in blood and water from different sources. The waste PP-based sensor was fabricated in the form of an emulsion-templated porous scaffold decorated with benzothiazolinium spiropyran (BTS), which produced a reddish colour upon exposure to Cu2+. The presence of Cu2+ was checked by naked eye, UV-Vis spectroscopy, and DC (Direct Current) probe station by measuring the current where the sensor's performance remained unaffected while analysing blood, water from different sources, and acidic or basic environment. The sensor exhibited 1.3 ppm as the limit of detection value in agreement with the WHO recommendations. The reversible nature of the sensor was determined by cyclic exposure of the sensor towards visible light turning it from coloured to colourless within 5 min and regenerated the sensor for the subsequent analysis. The reversibility of the sensor through exchange between Cu2+- Cu+ was confirmed by XPS analysis. A resettable and multi-readout INHIBIT logic gate was proposed for the sensor using Cu2+ and visible light as the inputs and colour change, reflectance band and current as the output. The cost-effective sensor enabled rapid detection of the presence of Cu2+ in both water and complex biological samples such as blood. While the approach developed in this study provides a unique opportunity to address the environmental burden of plastic waste management, it also allows for the possible valorization of plastics for use in enormous value-added applications.

Electrospinning of a Near Gel Resin To Produce Cross-Linked Fibrous Matrices.

Electrospun fibers and matrices have been researched for their utility in various fields; however, because of poor mechanical strength and loss of structural integrity, their commercial viability is limited. A near gel resin (nGR) of polystyrene (PS) was used in the present approach to fabricate cross-linked fibrous matrices of better mechanical strength and oil adsorption while retaining the structural integrity. Electrospinnability of nGR was assessed in bulk (i.e., in styrene monomer) and solution (i.e., in dimethyl formamide) forms with variations in formulation and electrospinning conditions. Ultimately, a uniform cross-linked fibrous matrix of PS was prepared using an oil-in-water emulsion, where the oil phase composed of a monomer (styrene), an initiator (benzoyl peroxide), and a cross-linker (divinylbenzene) was dispersed in a continuous phase of aqueous poly(vinyl alcohol) (PVA). The monomer conversion in the oil phase was carried out below the gel point, and the nGR of PS formed in dispersed droplets was electrospun to fabricate uniform fibrous matrices with the help of a template polymer, that is, PVA. The effect of various material and process parameters on the gelation behavior, electrospinnability, and fiber uniformity was studied and optimized to produce uniform core-sheath fibrous matrices of cross-linked PS. Postelectrospinning heat treatment of matrices was carried out to achieve complete monomer conversion and cross-linking. Fiber formation behavior of the emulsion was assessed using ionic and nonionic surfactants. The cross-link density of the matrices was optimized to achieve the desired structural morphology and dimensional stability. The process of fabrication of emulsion electrospun cross-linked fibers can be further extended to a variety of other monomers in order to enhance the suitability of fibrous matrices for many applications.

Cellulose-Derived Nanographene Oxide Reinforced Macroporous Scaffolds of High Internal Phase Emulsion-Templated Cross-Linked Poly(ε-caprolactone).

Cellulose-derived nanographene oxide (nGO)-type carbon dot reinforced porous scaffolds of poly(ε-caprolactone) (PCL) were developed as templates from high internal phase emulsions (HIPE). The mechanical strength, structural integrity, and reusability of the scaffolds were enhanced via in situ cross-linking. An oil-in-oil (o/o) HIPE of ε-caprolactone monomer (CL) was made for this purpose, and the ring-opening polymerization of a continuous phase comprised of CL, catalyst (Sn(Oct)2), and cross-linker (bis(caprolactone-4-yl)) (BCY) was carried out. The functionalization of scaffolds with nGO was assessed along with its role as an effective Pickering stabilizer of the HIPEs. The pore size and porosity of the scaffolds were governed by HIPE morphology, which in turn was controlled by the amount of nGO and the volume fraction of the dispersed phase. The nGO-functionalized scaffolds of cross-linked PCL thus prepared were characterized for their morphological structure, mechanical strength, and oil sorption capacity. Enhanced oil adsorption of nGO-functionalized scaffolds proved them to be of higher potency compared to those made of neat PCL. Superior compressive strength and reusability of scaffolds for oil adsorption up to 40 times while maintaining the structural integrity for ≥25 sorption-desorption cycles added extra value to such scaffolds. The scaffolds also had excellent cell viability as evaluated by MG63 osteoblast-like cells and some bioactivity in the form of calcium phosphate mineralization on the surface of the scaffolds.

Fluorescence resonance energy transfer in multifunctional nanofibers designed via block copolymer self-assembly.

In the present study, we demonstrate the fabrication of multifunctional nanofibers, loaded with CdSe quantum dots (QDs) and sulforhodamine 101 (S101) dye, via the self-assembly process of a polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP). The CdSe QDs and S101 dye were simultaneously incorporated in the cylindrical domains, constituted of P4VP blocks, of the self-assembled BCP structure. The cylindrical domains subsequently were isolated as individual nanofibers via the selective-swelling approach. The confinement imposed due to the nano-dimension geometry of the cylindrical domains enabled the QDs and S101 dye to localize within their Förster radius enabling an efficient fluorescence resonance energy transfer (FRET) between them. The mean lifetime of donor emission varied from 4.56 to 3.38 ns with the change in the ratio of S101 dye and CdSe QDs within the nanofibers. Furthermore, using efficiency measurements and the corresponding Förster distances, donor-acceptor distances were determined. Moreover, the kinetics of energy transfer from CdSe QDs to S101 was studied by the Poisson binding model, to understand the interactions between CdSe QDs and S101 dye molecules. The numbers of dye molecules per CdSe QD were determined, by assuming random distribution of S101 dye molecules around the CdSe QDs in the nanofibers. The results showed that the number of dye molecules per QD increased with increasing concentration of dye molecules in the nanofibers. The resulting multifunctional nanofibers could have potential applications in optoelectronics, photonics and sensors which utilize the FRET process.

Facile Fabrication of Composite Electrospun Nanofibrous Matrices of Poly(ε-caprolactone)-Silica Based Pickering Emulsion.

Functionalized matrices have been sought for their application in sensors, filtration, energy storage, catalysis, and tissue engineering. We report formation of an inorganic-organic composite matrix based on poly(ε-caprolactone) (PCL) functionalized with hydrophobically modified silica (m-silica) fabricated with reduced organic solvent usage. The matrix was obtained via electrospinning of a water-in-oil emulsion of PCL that was stabilized by judicious choice of m-silica as a Pickering agent resulting into an emulsifier free matrix. Inclusion of m-silica in PCL matrix resulted in enhancing tensile properties and cell proliferation efficiency. The electrospun composite matrix was free from any emulsifier or template polymer; thus any abrupt loss in mechanical properties was prevented when the matrix was subjected to aqueous conditions. The inorganic-organic biodegradable composite matrices thus produced using an emulsifier free emulsion find applications in tissue engineering and may further be evaluated for other areas including selective sorption and separation.

Starch-Derived Nanographene Oxide Paves the Way for Electrospinnable and Bioactive Starch Scaffolds for Bone Tissue Engineering.

A straightforward process that enabled electrospinning of bioactive starch-based nanofiber scaffolds was developed by utilizing starch derived nano graphene oxide (nGO) as a property enhancer and formic acid as a solvent and esterification reagent. The reaction mechanism and process were followed by detailed spectroscopic investigation. Furthermore, the incorporation of nGO as a "green bioactive additive" endorsed starch nanofibrous scaffolds several advantageous functionalities including improved electrospinnability and thermal stability, good cytocompatibility, osteo-bioactivity, and retained biodegradability. The biodegradable starch/nGO nanofibers underwent simultaneous degradation and mineralization process during 1 week of cell culture and mineralization test, thus, mimicking the structure and function of extracellular matrices (ECMs) and indicating promise for bone tissue engineering applications.

Crystallization behavior of crystalline/crystalline polymer blends under confinement in electrospun nanofibers of polystyrene/poly(ethylene oxide)/poly(ε-caprolactone) ternary mixtures.

We have studied the crystallization behavior of crystalline/crystalline blends of poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL) in electrospun nanofibers fabricated from ternary blends of polystyrene (PS), PEO, and PCL, where PS was present as the majority component. It was demonstrated previously that PEO in PS/PEO binary blend nanofibers with a low PEO weight fraction (≦0.2) crystallized predominantly through homogenous nucleation due to the small PEO domain size which excluded the presence of heterogeneities (Soft Matter, 2016, 12, 5110). Here, it was found that PCL in PS/PCL binary blend nanofibers exhibited similar behavior, but at a much lower weight fraction of PCL (≦0.1) due to the presence of an inherently higher concentration of heterogeneities in the PCL homopolymer. In the PS/PEO/PCL ternary blend nanofibers, where the combined weight fraction of PEO and PCL was kept at 0.2 or less, the crystallization of the two components took place separately through both heterogeneous and homogenous nucleation mechanisms. The phase segregated crystallization behavior was further confirmed by the melting behavior of the blend nanofibers and wide angle X-ray diffraction (WAXD) measurements. Most significantly, the homogenous nucleation of both PEO and PCL was suppressed whereas the heterogeneous nucleation was enhanced in the ternary blend nanofibers even at very low weight fraction of PEO or PCL. This was plausibly attributed to the coupling between the crystallization and the liquid-liquid phase separation (LLPS) of the PEO/PCL mixture dispersed in the PS matrix during non-isothermal cooling of the blend nanofibers. Furthermore, it was observed that thermal treatment of the PS/PEO/PCL blend nanofibers above the glass transition temperature of PS further promoted the heterogeneous nucleation-initiated crystallization of PEO because of a complex interplay between Plateau-Rayleigh instability-induced domain breakup and its further coalescence and demixing within the PEO/PCL domains embedded in the PS matrix.

Ligand displacement induced morphologies in block copolymer/quantum dot hybrids and formation of core-shell hybrid nanoobjects.

We investigate the self-assembly of a cylinder-forming polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) mixed with trioctylphosphine oxide (TOPO) capped cadmium selenide (CdSe) quantum dots (QDs). The QDs were found to be enthalpically compatible with the P4VP chains via ligand displacement of TOPO from the QD surface. However, the QDs were found to localize preferentially at the PS/P4VP interphase plausibly to gain translational entropy in order to further lower the energetics of the self-assembled structure. Interestingly, the morphological transformation observed with increasing weight fraction of the QDs in the BCP/QD composite was driven by the migration of the displaced TOPO from the QD surface to the PS phase, effectively increasing its total volume fraction. Hence, the PS-b-P4VP BCP with PS as the minority block displayed lamellar morphology in its composite with QDs. Furthermore, the preferred localization of the QDs at the PS/P4VP interface led to the formation of a trilayer lamellar morphology which was deduced from the suppression of the primary scattering peak, relative to higher order peaks in the SAXS data. The morphological transformation was accompanied by a significant increase in the domain spacing due to excessive stretching of the longer P4VP chains of the asymmetric block copolymer. However, in the PS-b-P4VP/CdSe composites with P4VP as the minority block, cylindrical morphology was retained and the domain spacing decreased due to dominance of the co-surfactant effect as well as interfacial localization of CdSe QDs. We also demonstrate that these PS-b-P4VP/CdSe self-assembled hybrid materials could further be used to obtain isolated core-shell nanoobjects, such as nanofibers and nanosheets, containing CdSe QDs. The nanoobjects so obtained exhibited photoluminescence properties typical of CdSe quantum dots. These photoluminescent polymer nanoobjects could have potential applications in biological targeting and fluorescence labeling.

Crystallization behaviour of poly(ethylene oxide) under confinement in the electrospun nanofibers of polystyrene/poly(ethylene oxide) blends.

We have studied the confined crystallization behaviour of poly(ethylene oxide) (PEO) in the electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO, where PS was present as the major component. The size and shape of PEO domains in the nanofibers were considerably different from those in the cast films, presumably because of the nano-dimensions of the nanofibers and the extensional forces experienced by the polymer solution during electrospinning. The phase-separated morphology in turn influenced the crystallization behaviour of PEO in the blend nanofibers. At a PEO weight fraction of ≥0.3, crystallization occurred through a heterogeneous nucleation mechanism similar to that in cast blend films. However, as the PEO weight fraction in the blend nanofibers was reduced from 0.3 to 0.2, an abrupt transformation of the nucleation mechanism from the heterogeneous to predominantly homogenous type was observed. The change in the nucleation mechanism implied a drastic reduction of the spatial continuity of PEO domains in the nanofibers, which was not encountered in the cast film. The melting temperature and crystallinity of the PEO crystallites developed in the nanofibers were also significantly lower than those in the corresponding cast films. The phenomena observed were reconciled by the morphological observation, which revealed that the phase separation under the radial constraint of the nanofibers led to the formation of small-sized fibrillar PEO domains with limited spatial connectivity. The thermal treatment of the PS/PEO blend nanofibers above the glass transition temperature of PS induced an even stronger confinement effect on PEO crystallization.

Helical packing of nanoparticles confined in cylindrical domains of a self-assembled block copolymer structure.

Theoretical models predict that a variety of self-assembled structures of closely packed spherical particles may result when they are confined in a cylindrical domain. In the present work we demonstrate for the first time that the polymer-coated nanoparticles confined in the self-assembled cylindrical domains of a block copolymer pack in helical morphology, where we can isolate individual fibers filled with helically arranged nanoparticles. This finding provides unique possibilities for fundamental as well as application-oriented research in similar directions.

Towards a low-emission resource circulation of valuable metals from municipal solid waste incineration fly ash.

The incineration fly ash (IFA) resulting from municipal solid waste combustion is laden with heavy metals, necessitating proper treatment not only for environmental management but also to reclaim the metal values. The surge in non-traditional metals like cobalt as emerging contaminant within IFA samples further attracts to address this issue. In response, the hydrometallurgical recycling of a cobalt-bearing IFA has been studied. Thereby, approximately 98 % zinc and 96 % cobalt were leached using a 1.0 mol/L H2SO4 solution at 90 °C and 1 h of leaching time. In-depth analysis of the leaching process unveiled metals' dissolution primarily via the ion-exclusion mechanism, as evidenced by lower diffusion coefficients (between 10-9 and 10-11 m2/s) and activation energies (9.6-14.9 kJ/mol). Above 99 % separation of zinc from the cobalt-bearing leach liquor was achieved by extraction with 1.0 mol/L D2EHPA at an equilibrium pH below 3.0, followed by stripping with a 2.0 mol/L H2SO4 solution. Cobalt, remained in the raffinate was efficiently precipitated by adding a 20 % excess dosage of oxalic acid to the stoichiometric ratio of C2O42-:Co2+, resulting in only 5 mg/L cobalt left in the solution when precipitation occurred at a pH of 2.8. Additionally, the conversion of CoC2O4 to high-purity Co3O4 was conducted through heat-treatment at 600 °C. The resulting Co3O4 was mixed with Li2CO3 at a Li/Co molar ratio of 1.1, yielding a LiCoO2 precursor that exhibited good electrochemical properties with a capacity of 128 mAh/g, thus affirming the high quality of the recycled cobalt. A comprehensive life-cycle assessment of the recycling process revealed that cobalt precipitation alone contributes approximately 50 % of the total global warming potential (GWP = 4.2624 kg CO2-eq). Notably, this value is remarkably lower than the GWP reported for primary cobalt production, highlighting the environmentally-friendly approach of this recycling endeavor.

Solid Polymer Electrolytes with Dual Anion Synergy and Twofold Reinforcement Effect for All-Solid-State Lithium Batteries.

Solid polymer electrolytes (SPEs) have emerged as a viable alternative to traditional organic liquid-based electrolytes for high energy density and safer lithium batteries. Poly(ethylene oxide) (PEO)-based SPEs are considered one of the mainstream SPE materials with excellent dissociation ability of lithium salts. However, the inferior ionic conductivity at room temperature and poor dimensional stability at high temperature limit their utilization. In this work, a semi-interpenetrating polymer network (semi-IPN) forming a precursor based on an ionic liquid (IL) monomer and linear PEO chains were introduced into an electrospun poly(acrylonitrile) (PAN) fibrous mat with subsequent thermal-initiated cross-linking. 1,4-Diazabicyclo [2.2.2] octane (DABCO) and 4-(chloromethyl) styrene were used to synthesize the styrenic-DABCO-based IL monomer with bis(trifluoromethane sulfonyl)imide (TFSI-) or bis(fluoromethane sulfonyl)imide (FSI-) as the anion, named as SDTFSI and SDFSI, respectively. Together, the FSI- and TFSI- anions demonstrate a synergistic effect in providing ion-conductive LiF and Li3N-rich inorganic SEI layer with enhanced lithium dendrite suppression ability. The twofold reinforcement effect is achieved collectively from the semi-IPN structure and the three-dimensional (3D) PAN network that help to construct highly efficient and uniform ion transport channels with excellent flexibility, further suppressing the lithium dendrite growth. The SPEs were dimensionally stable even at elevated temperatures of 150 °C. Moreover, the SPEs show an ionic conductivity of 4.4 × 10-4 S cm-1 at 25 °C and 1.81 × 10-3 S cm-1 at 55 °C and a lithium-ion transference number of 0.56. The favorable electrochemical performance of the SPEs was verified by operating LiFePO4/Li and NMC/Li cells.

Physics of moderately stretched electrified jets in electrohydrodynamic jet printing.

Electrohydrodynamic (EHD) jet printing involves the deposition of a liquid jet issuing from a needle stretched under the effect of a strong electric field between the needle and a collector plate. Unlike the geometrically independent classical cone-jet observed at low flow rates and high applied electric fields, at a relatively high flow rate and moderate electric field, EHD jets are moderately stretched. Jetting characteristics of such moderately stretched EHD jets differ from the typical cone-jet due to the nonlocalized cone-to-jet transition. Hence, we describe the physics of the moderately stretched EHD jet applicable to the EHD jet printing process through numerical solutions of a quasi-one-dimensional model of the EHD jet and experiments. Through comparison with experimental measurements, we show that our simulations correctly predict the jet shape for varying flow rates and applied potential difference. We present the physical mechanism of inertia-dominated slender EHD jets based on the dominant driving and resisting forces and relevant dimensionless numbers. We show that the slender EHD jet stretches and accelerates primarily due to the balance of driving tangential electric shear and resisting inertia forces in the developed jet region, whereas in the vicinity of the needle, driving charge repulsion and resisting surface tension forces govern the cone shape. The findings of this study can help in operational understanding and better control of the EHD jet printing process.

"Biomass to Membrane": Sulfonated Kraft Lignin/PCL Superhydrophilic Electrospun Membrane for Gravity-Driven Oil-in-Water Emulsion Separation.

Biobased membranes made with green solvents have numerous advantages in the water purification industry; however, their long-term use is impeded by severe membrane fouling and low structural stability. Herein, we proposed a facile and green approach to fabricate an eco-friendly and biodegradable electrospun membrane by simply blending polycaprolactone (PCL) with sulfonated kraft lignin (SKL) in a green solvent (i.e., acetic acid) without needing any additional post-treatment. We investigated the influence of SKL content on the surface morphology, chemical composition, and mechanical properties of the electrospun membrane. The SKL-modified membranes (L-5 and L-10) showed superhydrophilicity and underwater superoleophobicity with a water contact angle (WCA) of 0° (<3 s) and an underwater-oil contact angle (UWOCA) over 150° due to the combined effect of surface roughness and hydrophilic chemical functionality. Furthermore, the as-prepared membranes demonstrated excellent pure water flux of 800-900 LMH and an emulsion flux of 170-480 LMH during the gravity-driven filtration of three surfactant-stabilized oil-in-water emulsions, namely, mineral oil/water, gasoline/water, and n-hexadecane/water emulsions. In addition, these membranes exhibited superior antioil-fouling performance with excellent separation efficiency (97-99%) and a high flux recovery ratio (>98%). The 10 wt % SKL-incorporated membrane (L-10) also showed consistent separation performance after 10 cyclic tests, indicating its excellent reusability and recyclability. Furthermore, the stability of the membrane under harsh pH conditions was also evaluated and proved to be robust enough to maintain its wettability in a wide pH range (pH 1-10).

Dual-functionalized Pickering HIPE templated poly(ɛ-caprolactone) scaffold for maxillofacial implants.

High internal phase emulsion (HIPE) templated poly (ɛ-caprolactone) (PCL) scaffolds have gained widespread attention for large-sized bone defects due to its tuneable 3D architecture and ease of fabricating crosslinked PCL (cPCL) scaffolds. However, extremely high stabilizer (surfactant or nanoparticle) concentration and negligence of microenvironment for regeneration sites like alveolar bones have restrained industrial acceptance of these scaffolds. Herein, we demonstrated the fabrication of nanocomposite cPCL scaffolds within Pickering HIPE templates stabilized using modified silica nanoparticles (mSiNP) concentrations as low as 0.1 to 1.0 wt%. Using an unconventional approach, the mSiNP Pickering stabilizer was added in dispersed phase, contradicting Bancroft's rule. The colloidal stability was attained due to faster drifting of mSiNP towards the interface when it was dispersed in silicone oil. Scaffolds with tuneable properties were fabricated by controlling the mSiNP concentration and ϕd. Further, cPCL scaffolds were functionalized using clove oil (CO) to improve their efficiency in eradicating S. aureus and E. coli by disrupting their cellular integrity. Additionally, formation of biofilm on the surface of the scaffolds was successfully inhibited by the incorporation of CO. CO-functionalized scaffolds demonstrated excellent cytocompatibility towards MG-63 cells allowing their successful adhesion and proliferation on the surface of the scaffolds.

Biotechnological recycling of hazardous waste PCBs using Sulfobacillus thermosulfidooxidans through pretreatment of toxicant metals: Process optimization and kinetic studies.

The present study dealt with the restricted microbial tolerance for lead and tin during bioleaching of waste printed circuit boards (WPCBs) and lower extraction yields of valuable metals. Pretreatment of WPCBs in 4.0 mol/L HNO3 at 90 °C for 180 min duration prominently dissolved the toxicant metals before the microbial mobilization of valuable metals. Acid pretreatment followed the first-order kinetics that exhibiting an intermediate-controlled mechanism with the apparent activation energy determined to be Ea(Pb), 25.1 kJ/mol and Ea(Sn), 21.9 kJ/mol. Thereafter, the parametric optimization of aeration rate, O2-enrichment, external CO2 supply, temperature, and time for bioleaching of ground WPCBs was examined using Sulfobacillus thermosulfidooxidans (strain RDB). A favourable condition for Cu-bioleaching under higher oxidative environment in comparison to Ni and Zn exhibited the auto-catalytic behaviour of Cu2+ in the biological system. More than 92% of valuable metals were extracted under the optimal condition of aeration rate, 0.5 L/min; O2-enrichement dosage, 30%; external CO2 supply, 0.1%; temperature, 55 °C; and time, 18 days. The bioleaching kinetics followed shrinking core model that exhibiting the shifting of mass transfer from chemically-controlled to the diffusion-controlled mechanism. This process offers two-fold advantages that restoring the valuable metals with low-emission biotechnological route for waste valorization.

Pickering Emulsion-Templated Nanocomposite Membranes for Excellent Demulsification and Oil-Water Separation.

A worldwide steady increase in oily wastewater, due to oil spillage and various industrial discharges, requires immediate efforts toward development of an effective strategy and materials to preserve the natural water bodies. Designing a superwettable fibrous membrane of robust structure and anti-fouling property for efficient separation of oil-water mixtures and emulsions is therefore highly demanding. The electrospun fibrous membrane, which possesses porosity and flexibility and properties including superwettability and tunable functionality, can be considered as apposite materials for this cause. In this approach, we combined two strategies, viz., Pickering emulsion and near gel resin (nGR) emulsion electrospinning together to produce a fibrous nanocomposite membrane for efficient oil-water separation and demulsification. nGR Pickering emulsions were stabilized using hydrophilic SiO2 nanoparticles and successfully optimized for fabricating the crosslinked core sheath-structured fibrous membrane. The prepared membrane provided twofold functionality due to the core sheath structure of the fibers. The crosslinked polystyrene core offered high oil adsorption capacity, whereas SiO2-functionalized crosslinked polyvinyl alcohol sheath provided a rough, superhydrophilic surface with underwater oleophobic behavior to the membrane. The optimized SiO2-Pickering emulsion-templated nanocomposite membrane demonstrated excellent underwater anti-oil adhesion behavior (UWOCA ∼148°) with efficient oil-water separation capacity of more than 99% and separation flux up to 3346 ± 91 L m-2 h-1. The membrane was evaluated against various oil-water emulsions and found to have a superior separation efficiency. Moreover, excellent anti-oil adhesion property provided the intact membrane, where consistent separation performance was achieved up to 10 separation cycles without any loss. The membrane was used for separation of hot oil-water emulsions and showed no structural disintegration or loss in separation performance when exposed to elevated temperatures. The developed nanocomposite membranes could efficiently be used for separation and demulsification, and their applications can be explored in various other fields including selective sorption, catalysis, and storage in future.