Liquid Displacement Method Research Articles

Silica-based geopolymers admixture of borosilicate waste glasses: A green material for gamma radiation shielding applications

The gamma shielding parameters of an admixture of waste borosilicate glass (BS) and geopolymer (GP) made from activated metakaolin are presented in the present study. The influence of the BS quantity on the density and different gamma shielding quantities is investigated over a wide gamma energy range. Four batches of the G-BS composite were prepared using the solid-state diffusion method, containing 0 (G), 10 % (G-10BS), 20 % (G-20BS), and 30 % (G-30BS) by weight of BS, respectively. The chemical compositions of the G-xBS samples were determined through X-ray fluorescence spectrometry. In addition, the density of the BS-doped geopolymers was determined using the liquid displacement method using deionized water as the displacement fluid. The theoretical determination of estimating shielding parameters began by estimating the mass (μρ) and linear (μ) attenuation coefficients of the geopolymers for photon energies in the range of 15 keV to 15 MeV using the XCOM data library. The B and Si content and density of the geopolymer samples increased as the BS weight proportion increased in the geopolymer. The values of the attenuation coefficients (ACs) decreased with energy. For μ, the decrease was from 9.1533 to 0.0355 cm−1, 6.7486 to 0.0374 cm−1, 10.2964 to 0.0396 cm−1, and 10.7722 to 0.0414 cm−1, while for μρ, it was 5.3217 to 0.0206 cm2 g-1, 5.3860 to 0.0206 cm2 g-1, 5.3627 to 0.0206 cm2 g-1, and 5.3594 to 0.0206 cm2 g-1, for G, G-10BS, G-20BS, and G-30BS, respectively. There are no significant differences between the photon energy absorption capacity of the geopolymers, especially at energies greater than 1 MeV. The photon buildup factors of the G-xBS samples have very close relative values with no clear order. The introduction of waste borosilicate glass is therefore a way of improving the photon attenuation capacity of geopolymer and, therefore, the potential of shielding applications of geopolymer-based concrete.

Effect of graphite, graphene oxide, and multi-walled carbon nanotubes on the physicochemical characteristics and biocompatibility of chitosan/hyaluronic acid/hydroxyapatite scaffolds for tissue engineering applications

Bone tissue engineering (BTE) is a promising alternative approach to the repair of damaged bone tissue. This study aims to fabricate and characterize scaffolds composed of chitosan (CS), hyaluronic acid (HA), hydroxyapatite (HAp), and a combination of graphite (Gr), graphene oxide (GO), and multi-walled carbon nanotubes (MWCNT) for BTE applications. The Gr and MWCNT were functionalized by acid oxidation, while the GO was synthesized using the improved Hummers' method. The scaffolds were prepared by lyophilization, and the physical, chemical, and biological properties were evaluated. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, mechanical testing, water contact angle, degradation, and biocompatibility assays were used to characterize the scaffolds. The degradation rate was determined using the liquid displacement method. Pores of different sizes were present on the surface of and throughout the scaffold. According to the FTIR results, the scaffolds contained functional groups that promote cell differentiation and proliferation. These scaffolds have compressive strength, Young's modulus, and toughness similar to cancellous bone, with reasonable porosity and controllable degradation rates. Biocompatibility testing confirmed that the scaffolds support cell proliferation and differentiation.

Design, fabrication, and characterization of 3D-printed ABS and PLA scaffolds potentially for tissue engineering

Additive manufacturing technologies are getting attention as a prospective substitute for conventional medical implant production methods owing to their unique manufacturing properties. In addition, biomaterials are required for bone repair and tissue engineering (BTE) techniques to provide scaffolds with the necessary biological and structural properties and improved performance. In this study, widely available biocompatible materials acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) are utilized for the design, fabrication, simulation, and mechanical characterization of 3D-printed scaffolds with two lay-down patterns potentially for bone tissue engineering. Mechanical properties of the 3D-printed scaffolds are determined by compression test and finite element analysis (FEA). Moreover, scanning electron microscope (SEM) images are also analyzed to determine the printing accuracy of the scaffolds. The porosity of the scaffolds is estimated both theoretically and through the liquid displacement method. Finally, the comparative analysis between PLA and ABS scaffolds indicates that the PLA scaffold has a higher potential for bone tissue regeneration. This study provides a notable engineering contribution by using a cost-efficient and easily available biomaterial as an alternative to bone tissue.

Design and fabrication of berberine-loaded electrospun nanofibers as the analgesic and anti-injury scaffold

In the current study, we fabricated an analgesic and anti-injury scaffold nanofibrous scaffold based on berberine-loaded electrospun nanofibers. First off, we applied simulation studies using Material Studio software and Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS III) forcefield to assess the interactions between the components of the structure. Then, the electrospinning method was used to synthesize the nanofibers and the nanofibers were characterized using SEM imaging, Liquid displacement method, release kinetics, DPPH assay kit, and MTT assay kit. The results of simulation studies revealed that the non-separation of berberine molecules from the polymer indicates the attractive interaction between the berberine and the PVP polymer and has created an interwoven structure. The findings of molecular dynamics are consistent with the results obtained from experimental data. Therefore, molecular dynamics simulation can be used as a virtual laboratory in research involving berberine and PVP polymer. The characterizations showed that the nanofibers are uniform, without any deformity and bead, with smooth surfaces. Moreover, the addition of Ber in different concentrations did not alter the structure of nanofibers. The porosity of the nanofibrous scaffolds was in the range of 50–70 %. The DPPH radical scavenging showed a dose-dependent antioxidant activity. MTT assay showed that the nanofibers were biocompatible. The results implied that the fabricated berberine-loaded electrospun nanofibers possess promising properties and can be applied as an analgesic and anti-injury scaffold.

3D interconnected porous PMMA scaffold integrating with advanced nanostructured CaP-based biomaterials for rapid bone repair and regeneration

Bioactive scaffolds with polymer and nanostructured bioactive glass-based composites are promising materials for regenerative applications in consequence of close mimics of natural bone composition. Poly methyl methacrylate (PMMA) is a highly preferred thermoplastic polymer for orthopedic applications as it has good biocompatibility. Different kinds of bioactive, biodegradable as well as biocompatible biomaterial composites such as Bioglass (BG), Hydroxyapatite (Hap), and Tricalcium phosphate (TCP) can be integrated with PMMA, so as to augment the bioactivity, porosity as well as regeneration of hard tissues in human body. Among the bioactive glass, 60S BG (Bioactive glass with 60 percentage of Silica without Sodium ions) is better materials among aforementioned systems owning to mechanical stability as well as controlled bioactive material. In this work, the fabrication of PMMA-CaP (calcium phosphate)-based scaffolds were carried out by Thermal Induced Phase Separation method (TIPS). X-ray diffractogram analysis (XRD) is used to examine the physiochemical properties of the scaffolds that evidently reveal the presence of calcium phosphate besides calcium phosphate silicate phases. The Field Emission Scanning Electron Microscopy (FESEM) studies obviously exhibited the microstructure of the scaffolds as well as their interconnected porous morphology. The PMMA/60S BG/TCP (C50) scaffold has the maximum pore size, measuring 77 ± 23 μm, while the average pore size ranges from 50 ± 20 to 80 ± 23 μm. By performing a liquid displacement method, the C50 scaffold is found to have the largest porosity of 50%, high hydrophilicity of 118.16°, and a compression test reveals the scaffolds to have a maximum compressive strength of 0.16 MPa. The emergence of bone-like apatite on the scaffold surface after 1st and 21st days of SBF immersion is further supported by in vitro bioactivity studies. Cytocompatibility and hemocompatibility analyses undoubtedly confirmed the biocompatibility behavior of PMMA-based bioactive scaffolds. Nano-CT investigation demonstrates that PMMA-CaP scaffolds provide more or less alike morphologies of composites that resemble the natural bone. Therefore, this combination of scaffolds could be considered as potential biomaterials for bone regeneration application. This detailed study promisingly demonstrates the eminence of the unique scaffolds in the direction of regenerative medicines.

Qualitative and Quantitative Means of Production of Biogas from Biodegradable Waste (Cow Dung) for Sustainable Energy

Aims: This study was carried out by analyzing the quantitative and qualitative of the biogas produced from cow dung by degrading mechanism. 32L of bioreactors was used for the study.
 Methodology: The bioreactors were constructed to imitate the fixed batch prototype. The study lasted for 30 days and it was carried out at the National Centre for Energy Research and Development, University of Nigeria,Nsukka. Slurry was prepared in bioreactors. The substrates in the bioreactors were water and cow dung (intestinal and abdominal waste). The pH, the total solids (TS), volatile solids (VS) and total volatile fatty acid (VFA) characteristics of the substrate before and after digestion were determined using standard method. Quantitative and qualitative analysis of biogas production was by liquid displacement and gas Analyzer methods
 Results: The results of the TS, VS and VFA were 400 mg/l, 92mg/l and 16.7 mg/l respectively in the predigested samples and 92 mg/l, 17.4mg/l and 28.3mg/l respectively in the post digested samples. The quantity of biogas produced at the first week was 8.5liters, 7.5litre and 6.1liter from the 4th day, 5th day and 8th days. The qualitative analysis showed that the prominent biogas produced was methane. 
 Conclusion: The results of the research concluded that high quantity of biogas can be produced using cow dung. Approaches and technology for more efficient biogas producing consortia are proposed.

Development of chemically synthesized hydroxyapatite composite with reduced graphene oxide for enhanced mechanical properties

A successful attempt has been made to improve the mechanical properties of Hydroxyapatite (HAp) and reduced graphene oxide (rGO) composite nanoparticles (NPs). Various proportions of HAp and rGO were synthesized to improve the mechanical properties. HAp NPs were prepared using the wet precipitation method and further calcined to form crystalline particles. The physicochemical characterization of the HAp NPs revealed that the crystalline size and percentage of crystallinity were calculated to be 42.49 ± 1.2 nm and 44% post calcination. Furthermore, the rGO-HA composites were prepared using ball milling and obtained in the shape of pellets with different ratios of rGO (10, 20, 30, 40, 50% wt.). The mechanical properties have been evaluated through a Universal testing machine. Compared to calcined HAp (cHAp), the strength of variants significantly enhanced with the increased concentration of rGO. The compressive strength of HA-rGO with the ratio of the concentration of 60:40% by weight is a maximum of about 10.39 ± 0.43 MPa. However, the porosity has also been bolstered by increasing the concentration of rGO, which has been evaluated through the liquid displacement method. The mean surface roughness of the composites has also been evaluated from the images through Image J (an image analysis program).

The hydroxyapatite modified 3D printed poly L-lactic acid porous screw in reconstruction of anterior cruciate ligament of rabbit knee joint: a histological and biomechanical study

Background3D printing technology has become a research hotspot in the field of scientific research because of its personalized customization, maneuverability and the ability to achieve multiple material fabrications. The focus of this study is to use 3D printing technology to customize personalized poly L-lactic acid (PLLA) porous screws in orthopedic plants and to explore its effect on tendon-bone healing after anterior cruciate ligament (ACL) reconstruction.MethodsPreparation of PLLA porous screws with good orthogonal pore structure by 3D printer. The hydroxyapatite (HA) was adsorbed on porous screws by electrostatic layer-by-layer self-assembly (ELSA) technology, and PLLA-HA porous screws were prepared. The surface and spatial morphology of the modified screws were observed by scanning electron microscopy (SEM). The porosity of porous screw was measured by liquid displacement method. Thirty New Zealand male white rabbits were divided into two groups according to simple randomization. Autologous tendon was used for right ACL reconstruction, and porous screws were inserted into the femoral tunnel to fix the transplanted tendon. PLLA group was fixed with porous screws, PLLA-HA group was fixed with HA modified porous screws. At 6 weeks and 12 weeks after surgery, 5 animals in each group were sacrificed randomly for histological examination. The remaining 5 animals in each group underwent Micro-CT and biomechanical tests.ResultsThe pores of PLLA porous screws prepared by 3D printer were uniformly distributed and connected with each other, which meet the experimental requirements. HA was evenly distributed in the porous screw by ELSA technique. Histology showed that compared with PLLA group, mature bone trabeculae were integrated with grafted tendons in PLLA-HA group. Micro-CT showed that the bone formation index of PLLA-HA group was better than that of PLLA group. The new bone was uniformly distributed in the bone tunnel along the screw channel. Biomechanical experiments showed that the failure load and stiffness of PLLA-HA group were significantly higher than those of PLLA group.ConclusionsThe 3D printed PLLA porous screw modified by HA can not only fix the grafted tendons, but also increase the inductivity of bone, promote bone growth in the bone tunnel and promote bone integration at the tendon-bone interface. The PLLA-HA porous screw is likely to be used in clinic in the future.

Pressure development and volume changes during frying and post-frying of potatoes

Pressure evolution and material deformation during frying and post-frying of foods affect transport processes and food's textural attributes. Pressure and volume measurements have received limited attention in the frying literature. In this study, the changes in moisture content, oil uptake, temperature, pressure, and volume were measured as a function of frying time for potato cylinders. The volume change immediately after frying and after the cylinders had cooled was measured using a modified liquid displacement method. Fried cylinders continued to shrink post-frying. During frying, pressure and temperature showed similar increasing trends followed by plateauing of the temperature and a drop in pressure in the core. The measured gauge pressure remained positive throughout frying (t=300s) and up to 100s after frying. The measured gauge pressure dropped to negative values for the remaining cooling period. The temperature decreased during cooling, which is expected to have led to water vapor collapse and a drop in gas pressure. A high capillary pressure is expected to have developed in the food matrix due to water loss, causing the effective gauge pressure to become negative. The negative gauge pressure is expected to drive oil uptake and shrinkage of the food matrix post-frying.

Highly resilient porous polyurethane composite scaffolds filled with whitlockite for bone tissue engineering

The present work is intended to provide a base for further investigation of the composite scaffolds for bone tissue engineering, and whitlockite/polyurethane (WH/PU) scaffolds, in particular. WH Ca18Mg2(HPO4)2(PO4)12 was successfully prepared by means of a chemical reaction between Ca(OH)2, Mg(OH)2 and H3PO4. WH/PU scaffolds were synthesized via in situ polymerization. Synthesized WH particles and WH/PU composite scaffolds were characterized using FTIR, XRD, SEM and EDS. The porosity of scaffolds was calculated by the liquid displacement method. The water contact angle of scaffolds was tested. Mechanical characterization of WH/PU composite scaffolds was evaluated according to monotonic and cyclic compression examination. MC3T3-E1 cells were employed to evaluate the cytocompatibility of scaffolds. The results showed that WH and PU were completely integrated into composite biomaterials. The maximum compressive strength and elastic modulus of WH/PU composite scaffold reached up to 5.2 and 14.1 MPa, respectively. WH/PU composite scaffold had maximum 73% porosity. The minimum contact angle of WH/PU composite scaffold was 89.16°. WH/PU composite scaffolds have a good elasticity. Cyclic compression tests showed that scaffold could recover 90% of its original shape 1 h after removing the load. WH/PU composite scaffolds exhibited a high affinity to MC3T3-E1 cells. WH/PU composite scaffolds significantly promoted proliferation and alkaline phosphatase activity of MC3T3-E1 cells when compared to those grown on tissue culture well plates. It is suggested that the WH/PU scaffolds might be suitable for the application of bone tissue engineering.

Biological activities of chitosan-salicylaldehyde schiff base assisted silver nanoparticles

ObjectivesThe nanobiotechnology era has sparked interest in the green synthesis of stable silver nanoparticles (Ag-NPs) without hazardous chemicals. As a result, the current study used chitosan-salicylaldehyde Schiff base (CSB) as a non-toxic, reducing and stabilizingagent to prepare stable silver nanoparticles. MethodsThe characterization of Ag-NPs impregnated chitosan-salicylaldehyde Schiff base was fulfilled using UV-Vis, FTIR, XRD and TEM studies. ResultsThe absorption band present around 425 nm in UV-Vis spectra indicated the formation of Ag-NPs. The appearance of a new band for the CN bond, deduction in the intensity of the CO group of salicylaldehyde and NH group of chitosan confirmed the formation of Schiff base and Ag-NPs in FTIR analysis. XRD pattern revealed the orientation and crystalline nature of Ag-NPs with 2θ at 38°, 46° and 54° related to Ag-NPs (JCPDS No. 04-0783), whereas the peak at 2θ = 27° associated with CSB. The total porosity of 53.24% was determined using the liquid displacement method. The CSB-Ag-NPs have good scavenging activity (46.25% and 49.35% activity in DPPH assay and H2O2 assay), great antibacterial (zone of inhibition 17 mm and 19 mm for E-Coli and Pseudomonas sp.), antifungal (18 mm for P. notatum), and anti-larvicidal activity, according to biological assessments. ConclusionsThe synthesised Ag-NPs were non-toxic to marine ecosystems in a safety bioassay test.

Fabrication, experimental study, and 2-D finite element computational homogenization of bone scaffolds under uniaxial and biaxial compressive loadings

In this research, a novel nanocomposite bone scaffold made up of Gelatin and Polypyrrole biopolymers and Akermanite and Magnetite bioceramics was fabricated utilizing the freeze-drying method. Fourier Transform Infrared (FTIR) spectroscopy and X-ray Diffraction (XRD) analysis were employed. The existing functional groups and crystalline phases were identified. Microscopic images were taken, and the mean pore cell size was 165.62 µm. According to the results of the liquid displacement method, the porosity was 68% ± 3%. The fabricated scaffolds showed maximum swelling of 1012% during 140 h. The bioactivity was monitored, and the formed Apatite layers were seen in microscopic images. The MTT assay was conducted by Osteoblast cells culture, and after 3 days, 100% cell viability was recorded. 2-D porous multiphase Representative Volume Elements (RVEs) were generated employing the modified Random Sequential Adsorption (mRSA) algorithm. Afterward, we imposed periodic boundary conditions on the boundaries of the RVEs. The homogenized elastic modulus along the X-axis was 14.81 kPa in biaxial compression. In this loading state, homogenized Young’s modulus along the Y-axis was 13.7 kPa. Homogenized Young’s modulus along Y-axis direction under uniaxial loading was 12.54 kPa. According to the micromechanical modeling results, non-isotropic behavior from such scaffolds was seen.

Fabrication, swelling behavior, and water absorption kinetics of genipin‐crosslinked gelatin–chitosan hydrogels

AbstractGelatin/chitosan hydrogels have attracted considerable attention over the last 2 decades in various fields of applications. In this paper, chemically crosslinked composite hydrogels with different gelatin‐to‐chitosan weight ratios were fabricated and crosslinked with different amounts of genipin via the solvent casting technique combined with freeze‐drying. Fourier‐transform infrared, scanning electron microscopy (SEM), liquid displacement method, and gravimetric analysis were used to examine the chemical, microstructural, and physical properties of the hydrogels. IR spectra confirmed the formation of covalent bonds between the amino groups of the parent's macromolecules and genipin. SEM micrographs indicated that the hydrogels possessed a highly porous structure with well‐defined pore geometries. The swelling capacity and degradation rate of the specimens reduced with increasing the amounts of chitosan and/or genipin. In‐depth swelling measurements revealed that the first‐order kinetic model was only applicable in the early stage of the swelling study; however, the water absorption behavior of the hydrogels was best described by the pseudo‐second‐order kinetic model (Schott's model) throughout the swelling experiment. The genipin‐crosslinked hydrogels were found to support MC3T3‐E1 cell proliferation. The results of this paper thus suggest the 1.5% genipin‐crosslinked gelatin/chitosan hydrogels as promising candidates for on‐demand drug delivery applications or more precisely osteoarthritis drug delivery systems.

Indirect Evaluation of the Porosity of Waste Wood Briquettes by Assessing Their Surface Quality

The briquette porosity is a quality characteristic known to be important for combustion analysis, heat and mass transfer processes during combustion stages, determination of effective thermal conductivity or other related properties. This paper describes a method to quantify the briquette porosity by some surface roughness parameters that can be useful for alternative, inexpensive and at hand evaluations. Porosity of briquettes manufactured with a hydraulic press from waste wood from secondary processing was calculated with three methods suggested in the literature for wood; of these, one was adapted here for a wet porosity model (called “general relation”) proposed for wood briquettes. Briquettes density was obtained by using two stereometric methods and a liquid displacement method. Correlations were examined between porosity, surface roughness parameters and density of briquettes. Very strong correlations with surface roughness were identified for porosity calculated with all three methods, when density was measured by one of the stereometric methods. These correlations can serve as a method to indirect evaluation of the briquettes porosity by assessing the surface quality.

Some Bio-Technical Properties of Flax Seeds, Fennel Seeds and Harmal Seed Capsules

Some bio-technical properties of flax seeds, fennel seeds, and harmal seed capsules were determined. The size dimensions (length, width, and thickness) of flax seeds and fennel seeds were as 4.31 mm, 2.28 mm, 0.87 mm; 6.93 mm, 2.13 mm, 1.75 mm, respectively. The diameter and length for harmal seed capsules were 9.07 mm and 6.65 mm, respectively. The true density (ρt) was determined using the liquid displacement method, and the bulk density (ρb) was determined using the hectolitre tester. The bulk density for flax seeds, fennel seeds, and harmal seed capsules were determined as 384.3 kg m-3, 270.5 kg m-3 and 201.5 kg m-3, while, true density was found as 1256.5 kg m-3, 664.6 kg m-3, 936.2 kg m-3 for flax seeds, fennel seeds, and harmal seed capsules, respectively. The sphericity of for flax seeds, fennel seeds and harmal seed capsules were obtained as 0.47, 0.43, 0.72, respectively. The angle of repose was obtained as 13.84º, 17.35º, 29.94º for flax seeds, fennel seeds, and harmal seed capsules, respectively. The rubber friction surface has given the highest static friction coefficient for flax seeds, fennel seeds, and harmal seed capsules.

Morphological and optical properties of porous hydroxyapatite/cornstarch (HAp/Cs) composites

This paper presents the correlation between the morphological characteristics and the diffuse reflectance (optical properties) of the porous hydroxyapatite/cornstarch (HAp/Cs) composites with various starch proportions (30, 40, 50, 60, 70, 80 and 90 wt%). The porous composites were measured via SEM and enhanced by image processing to find the average pore size, strut width, and average surface roughness. The average porosity of the porous composites was measured using liquid displacement method. The diffuse reflectance spectroscopy was implemented to investigate the diffuse reflectance and the corresponding optical band gap energy of the porous composites in the 500–900 nm range. A relationship between morphological characteristics and diffuse reflectance properties were established using Pearson's correlation coefficient. The findings of the study depict that a strong correlation can be noticed between optical band gap energy with porosity, pore sizes and surface roughness of the porous composites. Meanwhile, the strong correlations between the diffuse reflectance spectral gradient with surface roughness can be observed. The moderate correlations can be observed between the diffuse reflectance spectral gradient with pore sizes and strut width of the porous composites.

Optimizing the physical parameters of polycaprolactone-gelatin-polydimethylsiloxane composite nanofiber scaffold for tissue engineering application

A lot of research has already been conducted on tissue engineering as it can have the potential for organ and tissue regeneration and repair. Research on the proliferation of cells on the scaffolds, which are material-based structures in the extracellular matrix, increased efficiency of 3D cultures. In this study, the stages of preparing a nanofiber scaffold with different ratios of three polymers of Polycaprolactone/Gelatin/Polydimethylsiloxane (PCL/G/PDMS) which is biodegradable, non-toxic and biocompatible are explained for tissue engineering and then fibroblast cells cultivation are discussed. The morphology, porosity and hydrophilicity of the prepared scaffolds were evaluated by scanning electron microscope (SEM), the liquid displacement method, water contact-angle measurements respectively. The cell growth and proliferation on scaffolds were counted by Digimizer© software. Then morphology, porosity and hydrophilicity of scaffolds and cell growth and proliferation on scaffolds were optimized by Response Surface Methodology (RSM). The results show that PCL/G/PDMS electrospun nanofibers can be used for tissue engineering applications. The purpose of this scaffold is design a scaffold for elastic tissue engineering, especially uterine tissue, which will be discussed in the following articles.

Removal studies of Pb (II) ions by carbon powder prepared from pοlyethylene terephthalate (PET) bοttles

ABSTRACT In this study, an innovative low-cost carbon powder that is obtained by pοlyethylene terephthalate (PET) bοttles waste was investigated for the removal of Pb (II) ions from aqueous solution. For this, carbon sample was characterised by a liquid displacement method, point of zero charge pH (pHPZC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). In addition to this, batch experiments were carried out to study the effect of the main parameters such as contact time, initial Pb (II) concentration, adsorbent dosage and pH of the medium on the adsorption process. As results, the maximum adsorption capacity reached 97.95 mg.g−1 with an initial Pb (II) concentration of 100 mg.L−1, pH = 6.0, sorbent concentration of 0.4 g.L−1, agitation speed of 360 rpm, and temperature of 20°C. Dynamic studies using the solver add-in with Microsoft Excel showed that the adsorption of Pb (II) is well described by a pseudo-second-order kinetic model, while its equilibrium isotherm analysed by Langmuir, Freundlich, Redlich–Peterson and Sips models confirmed that the Langmuir isotherm model is in good agreement with the experimental data of the process. From environmental and economic view, the results of the present study show that PET waste is advantageous and an effective adsorbent for the elimination of lead from aqueous solutions.

Equilibrium Study, Modeling and Optimization of Model Drug Adsorption Process by Sunflower Seed Shells

The adsorption capacity of the medication methylthioninium chloride (MC) from aqueous solution onto sunflower seed shells (SSS), a low cost and abundant alternative adsorbent, was investigated in a batch system. The surface properties of the adsorbent were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), specific surface area (by using the Brunauer–Emmett–Teller equation), the liquid displacement method and pHPZC. The ability of SSS to remove the medication was assessed through kinetic, thermodynamic and equilibrium investigations. The adsorption efficiency of the SSS adsorbent for the removal of MC was evaluated considering the effects of its concentration, temperature, adsorption contact time, and the pH of the medium. The results obtained from the kinetic and isotherm studies show that the adsorption of the MC on SSS follows pseudo-second-order kinetics (R² > 0.99) and the Temkin isotherm model (R² = 0.97), respectively. The thermodynamic study showed that the adsorption was endothermic and spontaneous, according to its physisorption mechanism. The mathematical modeling of this process was carried out by using the surface response methodology of Box–Behenken. It was possible to deduce a statistically reliable regression equation that related the adsorption yield to the chosen operating parameters, that is, the initial MC concentration, the adsorbent dosage and the pH. Analysis of the variance indicated that the most influential parameters were the SSS dosage, the pH and their interaction and showed the optimal values for ensuring the best adsorption capacity of 95.58%.

In-situ formation of composite having hard outer layer based on aluminum dross reinforced by SiC and TiO2

In-situ formed two-layer composite was prepared from aluminum dross reinforced with various percentages of SiC and TiO2. Nano powder mixtures were prepared by mechanical alloying. X-ray diffraction (XRD) and transmission electron microscopy were utilized to evaluate the milled powders. The powders were cold pressed under 20 MPa and sintered for 1 h at 1500 °C. The sintered samples were investigated by XRD and scan electron microscopy. Bulk density and apparent porosity were also determined by liquid displacement method. The microhardness, fracture toughness, elastic moduli and electrical conductivity were also studied. The results revealed that a significant reduction in crystallite size was occurred after milling the powder. After sintering, two-layer composite was in-situ formed. The reinforcements were homogenously distributed in the matrix with formation of new phase as TiC. The bulk density was increased while the apparent porosity was decreased with increasing the reinforcement's content. Furthermore, mechanical properties of outer layer were enhanced with increasing the amount of reinforcements; its hardness was higher than that of the inner layer. The electrical conductivity of whole-bulk composite was also increased with increasing the reinforcement percentage.