Porous Rough Surface Research Articles

Sol-gel synthesis of composite adsorbent coating from Prosopis juliflora–activated carbon for simultaneous adsorptive removal of Cd2+ and Cr2O72- from wastewater

ABSTRACT To overcome the challenges associated with powdered activated carbon (PAC) in water and wastewater treatment, the efficacy of composite adsorbent coating (CAC) synthesized using a simple sol-gel method with Prosopis juliflora-activated carbon for the simultaneous reduction of Cd2+ and Cr2O72− was investigated. The CAC was characterized by FTIR (C-H, C = O, and O-H stretching), pHPZC (6 -6.6), SEM (porous-rough surface), and BET surface area (10.6 m2/g) techniques. Statistical analysis confirmed that pH and contact time significantly (p < 0.0001) affected both metal ions removal, with Cd2+ removal generally exceeding that of Cr2O72− due to better ionic properties. Using the optimized conditions (8.5 pH, 0.25 dosage, 5 mg concentration, 105 minutes contact time and 23.73 °C temperature), the predicted and experimental ion removal efficiencies were 86.86 and 83.98% for Cd2+ and 94.26 and 58.08% for Cr2O72−, respectively. The Langmuir adsorption isotherm was the best-suited model (R2 > 0.99), while the metal ions removal was regulated by the PSO kinetic model (R2 > 0.999). The adsorption process was endothermic and spontaneous, as indicated by thermodynamic values (−ΔG°, +ΔH°, +ΔS°). The study demonstrates CAC's effectiveness as an alternative to PAC, offering significant advantages in removing metal ions from wastewater.

Scalable fabrication of porous membrane incorporating human extracellular matrix-like collagen for guided bone regeneration.

Guided bone regeneration (GBR) is an extensively used technique for the treatment of maxillofacial bone defects and bone mass deficiency in clinical practice. However, to date, studies on membranes for GBR have not achieved the combination of suitable properties and cost-effective membrane production. Herein, we developed a polycaprolactone/human extracellular matrix-like collagen (PCL/hCol) membrane with an asymmetric porous structure via the nonsolvent-induced phase separation (NIPS) method, which is a highly efficient procedure with simple operation, scalable fabrication and low cost. This membrane possessed a porous rough surface, which is conducive to cell attachment and proliferation for guiding osteogenesis, together with a relatively smooth surface with micropores, which allows the passage of nutrients and is unfavorable for the adhesion of cells, thus preventing fibroblast invasion and overall meeting the demands for GBR. Besides, we evaluated the characteristics and biological properties of the membrane and compared them with those of commercially available membranes. Results showed that the PCL/hCol membrane exhibited excellent mechanical properties, degradation characteristics, barrier function, biocompatibility and osteoinductive potential. Furthermore, our in vivo study demonstrated the promotive effect of the PCL/hCol membrane on bone formation in rat calvarial defects. Taken together, our NIPS-prepared PCL/hCol membrane with promising properties and production advantages offers a new perspective for its development and potential use in GBR application.

Development of multifunctional bioactive food packaging based on silver nanoparticles/grape fruit peel extract reinforced PVA composites

Active food packaging based on bio-wastes has gained considerable attention these days due to their ecofriendly and biodegradable behavior. In this study, multifunctional bio-composite films with remarkable anti-oxidant and anti-microbial attributes were synthesized by incorporating biosynthesized silver nanoparticles (AgNPs) and grape fruit peel extract (GFPE) into polyvinyl alcohol (PVA) matrix. Synthesized films were characterized in terms of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC) and Dynamic Mechanical Analyzer (DMA). Antioxidant activity of AgNPs-GFPE/PVA films was determined by %DPPH scavenging ability and Ferric reducing antioxidant power assay while antimicrobial activity was measured by agar diffusion method. XRD analysis revealed the semi-crystalline behavior of synthesized composites with characteristics peak at 38° whereas SEM micrographs confirmed the homogeneous dispersion of reinforcement and porous rough surface structure of AgNPs-GFPE/PVA nano-composites. AgNPs-GFPE/PVA nanocomposite exhibited glass transition temperature (Tg) at ∼116 °C and Tm ∼191 °C along with the storage modulus of 685 MPa, revealing significantly enhanced thermal and mechanical stability of composites compared to pure PVA films. The composite films exhibited remarkable antioxidant potential i.e DPPH scavenging activity ∼50 % and reducing power ∼ 0.58. The AgNPs-GFPE/PVA nano-composite films exhibited remarkable antimicrobial activity in response to food borne pathogens. The results designated that the synthesized composite films have prodigious potential of being cheap, eco-friendlier substitute to conventional materials for application in food packaging, which certify the safety and economical life span of packed food.

Heat Transfer on Micro and Nanostructured Rough Surfaces Synthesized by Plasma

The review summarizes recent experimental results of studying heat transfer on rough surfaces synthesized by plasma. The plasma-surface interaction leads to the stochastic clustering of the surface roughness with a high specific area breaking the symmetry of the virgin surface of the initial crystalline materials. Such a surface is qualitatively different from the ordinary Brownian surface. The micro- and nanostructured surface consist of pores, craters, and nanofibers of size from tens of nanometers to tens of microns, which can provide new heat transfer properties related to a violation of the symmetry of the initial materials. In recent years, new results have been obtained in the study of heat transfer during phase change on plasma-modified surfaces in relation to energy, chemical, and cryogenic technologies. The objective of the review is to describe the specific structure of refractory metals after high-temperature plasma irradiation and the potential application of plasma processing of materials in order to create heat exchange surfaces that provide a significant intensification of two-phase heat transfer. Refractory metals with such a highly porous rough surface can be used as plasma-facing components for operation under extreme heat and plasma loads in thermonuclear and nuclear reactors, as catalysts for hydrogen production, as well as in biotechnology and biomedical applications.

Microstructure of gamma-ray developed polymeric nanocomposite respecting cesium and cobalt removal from aqueous solutions

The nanoparticles of fly ash (FA) were obtained by high energy ball milling of their parent Class C kind for subsequent synthesis of poly(acrylamide-acrylic acid)/fly ash (poly(AM-AA)/FA) nanocomposite. The gamma-radiation induced polymerization was applied to achieve this concern. Different techniques were utilized to characterize such nanocomposite. The sorption abilities of the synthesized nanocomposite toward 60Co2+ and 134Cs + radionuclides were evaluated using batch and fixed-bed column approaches. Batches were designed at constants of solution pH (6.5–7.0 ± 0.02), nanocomposite particle size and dosage (106–250 μm and 0.1 L/g, respectively). The microstructure of such nanocomposite (<100 nm) was mainly amorphous with porous rough surfaces containing homogenous distribution of the incorporated nano-FA. About 56.46 and 47.9 mg/g of Co2+ and Cs+ were sorbed at equilibrium with an ion exchange reaction mechanism. Langmuir, Freundlich and Dubinin–Radushkevich D–R isotherm model parameters were calculated indicating the favorability of all sorption processes. The spontaneous and endothermic natures of sorption were observed by the calculated ΔG° and ΔH° thermodynamic parameters, respectively. Thomas, Yoon–Nelson and Adams Bohart models were fitted to the fixed-bed column data at varied conditions. The predicted sorption capacities of Thomas were very close to those obtained experimentally. Modeling of the fixed-bed column data dominates that the external mass transfer kinetics was predominant in the initial parts of the fixed-beds. Values required for retaining 50% of the initial sorbate concentration were extended from 89.05 to 68.55 to 177.2 and 149.3 min for 60Co2+ and 134Cs + radionuclides, respectively, by increasing bed depth from 1.5 to 3.0 cm. Modification of FA to its nano-scale form with the subsequent synthesis of a nanocomposite material having sorption capabilities made a duplicate beneficial environmental concern.

One-step electrospinning PCL/ph-LPSQ nanofibrous membrane with excellent self-cleaning and oil-water separation performance

The ladder-like phenyl polysilsesquioxane (ph-LPSQ) was synthesized by sol-gel method. Then the Polycaprolactone/ladder-like polysilsesquioxane (PCL/ph-LPSQ) nanofibrous membranes were prepared via one-step electrospinning technique. The addition of ph-LPSQ was proposed to improve the hydrophobic and thermal properties of PCL membranes. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images showed the PCL/ph-LPSQ composite fibers had porous rough surface structure, which was caused by solvent evaporation induced phase separation, respiration diagram and silicon segment migration. The composition of PCL/ph-LPSQ membranes was characterized by using fourier transform infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectroscopy (EDS). Compared with pristine PCL membranes, the water contact angle and initial degradation temperature for PCL/ph-LPSQ membranes were increased to 158.0° and 355 °C, respectively, from the corresponding 133.6° and 340 °C. The superhydrophobic PCL/ph-LPSQ membranes exhibited excellent self-cleaning, anti-fouling and oil-water separation performance. Driven by gravity alone, the oil-water separation efficiency remained as high as 98% after ten cycles. More importantly, the as-prepared membrane showed good stability in 80 °C, 1 M acid, alkali and salt solutions. Considering the comprehensive properties of PCL/ph-LPSQ membranes, it might be a promising nonwoven fabric material in many fields like textile manufacturing industry. • A facile and ingenious method of preparing super hydrophobic nanofibrous membrane was developed in this paper. • The thermal and hydrophobic properties of the composite membrane were improved with the addition of organo-silicon polymer. • The as-prepared membranes exhibited excellent self-cleaning and oil-water separation performance.

Effects of Reaction Time on Degree of Substitution, Yield and Morphology of Carboxymethyl Cellulose from Banana Peel

Carboxymethyl cellulose(CMC) was extracted from cultivated banana peel (BP) agricultural waste. Cellulose was first extracted from BP through delignification, bleaching and hydrolysis processes. Then, CMC was prepared by the carboxymethylation reaction using monochloroacetic acid as a modifying agent. A mixture of 30% sodium hydroxide solution and isopropanol was used as the solvent medium for etherification with reaction time of 1-5 hours. The effects of reaction time on physical appearance, chemical structure, degree of substitution (DS), percent yield (%yield) and morphology of CMC were studied. Results indicated that banana peel cellulose (BPC) powder could be extracted from BP with yield of 14.81%±7.20. CMC was successfully prepared from BPC powder and confirmed by FT-IR technique. DS and %yield of CMC increased when reaction time increased from 1 to 4 hours but decreased when reaction time reached 5 hours. Reaction time of 4 hours gave optimal DS and %yield at 0.61±0.05 and 152.65±17.93, respectively. BPC presented bulk particle shape with a dense and smooth surface. After etherification, morphology of BPC was changed to a mixture of small particles with fibrous shape and a porous rough surface.

Preparation of durable superamphiphobic cotton fabrics with self-cleaning and liquid repellency

A durable superamphiphobic cotton fabric was obtained by coating SiO2 aerogel particles, polydimethylsiloxane (PDMS), and 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFTES) on a cotton fabric via the dip-pad-dry process. The surface morphology, chemical composition, and thermal degradation behavior characterization of the as-prepared cotton fabric (PFTES/PDMS/SiO2@Cotton fabric) were performed, respectively. It was proved that the coated cotton fabric was successfully covered with PFTES/PDMS/SiO2. The porous rough surface topology structure due to the SiO2 aerogel particles along with low surface energy because of the fluorinated chains and PDMS adhesive layer on the as-obtained PFTES/PDMS/SiO2@Cotton fabric can trap a layer of air, endowing the coated fabric durable superamphiphobicity. The prepared superamphiphobic cotton fabric with a water contact angle (WCA) of 159.0 ± 0.8° and an oil contact angle (OCA) of 154.5 ± 0.7° showed good liquid repellence for common liquids in daily life like orange juice, cola, coffee, and milk, exhibiting excellent self-cleaning and stain-resistance property. Moreover, the superamphiphobic cotton fabric possessed good durability and still maintained superamphiphobicity after mechanical abrasion for 1500 cycles or ultraviolet (UV) irradiation for 96 h. This superamphiphobic cotton fabric exhibited potential applications in various fields due to the high repellency to various liquids.

Multi-3D hierarchical biomass-based carbon particles absorber for solar desalination and thermoelectric power generator

To meet challenges of the global energy crisis and the freshwater resources shortage, the interfacial solar-to-steam conversion (ISSC) system was developed quickly in recent years. The photothermal materials play an important role in the ISSC system. We are devoted to developing a unique photothermal material integrating multiple 3D design philosophy both at macroscopic and microscopic levels by employing the cost-effective and widespread resources like straw, rose and coffee grounds, for carbonization as solar absorbers. The biomass-based carbonized particles (CPs) possess three major advantages: (1) wide size-distribution is accessible to form 3D porous rough surface of absorber layer to enhance ability of light absorption; (2) the pristine hierarchical microstructure could absorb nearly all the incident light; (3) the intrinsic vascular bundles with pores on their lumen walls provide a rapid and omnidirectional transport for water and steam escape. A high-efficient solar steam device was fabricated based on the absorber material with its internal 3D micro textures and external 3D architectures. Under the illumination of 1 sun, the photothermal conversion efficiency of straw, rose and coffee CPs can reach 93.4 %, 92.8 % and 76 %, respectively. Simultaneously, a high-efficient solar thermoelectric generator (STEG) is made by coating CPs on a commercial thermoelectric generator and the maximum power of STEG can reach 538.0 μW. Such scalable biomass-based photothermal materials and high-grade thermoelectric conversion capability could be applied to the water purification and the electricity production.

Retroreflection of Optical Radiation from Ellipsoidal-Porous Surfaces

The retroreflection of optical radiation from surfaces with roughness in the form of ellipsoidal pores and two-level roughness in the form of convex ellipsoids with elliptical-porous surfaces is studied using the ROKS-RG Monte-Carlo method software in the geometrical-optics approximation. The dependence of the retroreflection phase function on the parameters of bodies that simulates the rough surface is analyzed. It is shown that the angular dependence of the retroreflection from porous rough surfaces with arbitrarily oriented pores and the aspect ratio higher than unity is a pronounced peak with concave sides at all incidence angles.

Effect of surface topography and bioactive properties on early adhesion and growth behavior of mouse preosteoblast MC3T3-E1 cells.

The effects of bioactive properties and surface topography of biomaterials on the adhesion and spreading properties of mouse preosteoblast MC3T3-E1 cells was investigated by preparation of different surfaces. Poly lactic-co-glycolic acid (PLGA) electrospun fibers (ES) were produced as a porous rough surface. In our study, coverslips were used as a substrate for the immobilization of 3,4-dihydroxyphenylalanine (DOPA) and collagen type I (COL I) in the preparation of bioactive surfaces. In addition, COL I was immobilized onto porous electrospun fibers surfaces (E-COL) to investigate the combined effects of bioactive molecules and topography. Untreated coverslips were used as controls. Early adhesion and growth behavior of MC3T3-E1 cells cultured on the different surfaces were studied at 6, 12, and 24 h. Evaluation of cell adhesion and morphological changes showed that the all the surfaces were favorable for promoting the adhesion and spreading of cells. CCK-8 assays and flow cytometry revealed that both topography and bioactive properties were favorable for cell growth. Analysis of β1, α1, α2, α5, α10 and α11 integrin expression levels by immunofluorescence, real-time RT-PCR, and Western blot and indicated that surface topography plays an important role in the early stage of cell adhesion. However, the influence of topography and bioactive properties of surfaces on integrins is variable. Compared with any of the topographic or bioactive properties in isolation, the combined effect of both types of properties provided an advantage for the growth and spreading of MC3T3-E1 cells. This study provides a new insight into the functions and effects of topographic and bioactive modifications of surfaces at the interface between cells and biomaterials for tissue engineering.

Particular features of the application of IR reflection spectroscopy methods in studies in archeology and paleontology

We have considered an optical model of a porous rough surface with optical properties of objects (bone, flint) that are typical of archeology and paleontology. We have formulated an approach that makes it possible to perform mathematical processing of the IR reflection spectra of objects of this kind using standard algorithms and determine criteria that ensure obtaining reliable information on objects with a rough surface in the course of interpretation of frequencies in their IR reflection spectra. The potential of the approach has been demonstrated using as an example an investigation by the IR Fourier-transform reflection spectroscopy of mineralization processes of mammoth tusks from two paleolithic sites (14000 and 16000 BCE) located by the town of Yudinovo, Bryansk oblast, Russia.

High-speed flames and DDT in very rough-walled channels

An experimental investigation of flame acceleration in a narrow rectangular cross-section channel with various lower boundary conditions is presented. The boundary conditions investigated include a smooth surface and a rough surface with and without porosity. Tests were performed with a mixture of nitrogen diluted stoichiometric methane–oxygen, i.e., CH4+2(O2+2/3N2), at initial pressures in the range of 9–15kPa. The explosion front velocity was measured via ionization probes and pressure transducers and the explosion wave front structure was visualized by high-speed shadowgraph video. For tests performed with a porous rough surface the flame achieves a velocity that approaches the speed of sound of the combustion products. In the case of the rough surface without porosity, a globally quasi-steady high-speed flame is produced with a velocity between the combustion products speed of sound and the Chapman–Jouguet detonation velocity. It is proposed that flame acceleration beyond the speed of sound of the combustion products is possible due to enhanced burning that is driven by chemical–acoustic interactions. Such interactions occur as the turbulent flame brush is traversed by transverse pressure waves produced by the passage of the explosion front shock wave over the rough surface. It is also observed that under certain conditions a smooth transition from a diffusion driven flame to a shock ignition detonation is possible.

A study of the galvanic replacement reaction at surfaces and the role of lateral charge propagation

The galvanic replacement of isolated nanostructures of copper and silver on conducting supports as well as continuous films of copper with gold is reported. The surface morphology was characterized by scanning electron microscopy and the replacement with gold was confirmed by EDX analysis. It was found that lateral charge propagation during the replacement reaction had a significant effect in all cases. For the isolated nanostructures the deposition of gold was observed not only at the sacrificial template but also at the surrounding unmodified areas of the conducting substrate. In the case of copper films the role of lateral charge propagation was also confirmed by connecting it to an ITO electrode through an external circuit upon which gold deposition was also observed to occur. Interestingly, by inhibiting the rate of charge propagation, through the introduction of a series resistor, the morphology of gold on the copper substrate could be changed from discrete surface decoration with cube like nanoparticles to a more porous rough surface.

Roughness characterization of porous soil with acoustic backscatter.

The use of acoustics to determine the pore properties of soils, such as porosity, permeability, and tortuosity, is well established. A theoretical surface impedance and complex bulk wavenumber was developed by K. Attenborough for porous media that incorporated the soil pore properties as parameters [J. Acoust. Soc. Am. 73, 785-799 (1983)]. Acoustic level difference measurements were used as a noninvasive means of finding the soil pore properties. Acoustic reflection measurements showed that the sound field over porous rough surfaces is modified by the surface impedance and by surface roughness. It is not possible to separate the signal modification due to impedance and the signal modification from roughness scattering in a forward scattering measurement. In order to accurately determine the soil pore properties, the roughness effects must be known independently from the surface impedance. A means of measuring roughness apart from impedance would allow the effects of roughness to be taken out of the level difference measurements. The underwater acoustics community has used acoustic backscatter for many years to examine surface roughness. The feasibility of adapting these acoustic backscatter techniques to outdoor porous soil surfaces is examined.