Modeling and Simulation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD

Membrane distillation is an active technique that provides pure water with very good rejection and could be applied to water of extremely high salinity. The low productivity of membrane distillation needs intensive efforts to be competitive with other desalination techniques. In this current study, a composite (PS/GNP) membrane, which is composed of polystyrene (PS) based and 0.25% weight percent graphene nanoplates (GNP) has been fabricated via electrospinning and compared with the blank PS membrane. SEM, FTIR, contact angle and porosity characterization have been performed, and the results show that the validity of the predefined conditions, and the contact angle of the composite membrane, which is found to be 91.68°, proved the hydrophobic nature of the composite membrane. A numerical simulation using Ansys 2020 software has been introduced to study the performance of the fabricated composite membrane when used in direct contact membrane distillation (DCMD). The numerical model has been validated with experimental work from the literature and showed an excellent match. The blank PS and composite PS/GNP membranes have been investigated and compared at different operating conditions, i.e., hot water supply temperature and system flow rate. The results show that the composite PS/GNP membrane outperforms the blank PS membrane at all studied operating conditions.

Image analysis method for heterogeneity and porosity characterization of biomimetic hydrogels

This work presents an image processing procedure for characterization of porosity and heterogeneity of hydrogels network mainly based on the analysis of cryogenic scanning electron microscopy (cryo-SEM) images and can be extended to any other type of microscopy images of hydrogel porous network. An algorithm consisting of different filtering, morphological transformation, and thresholding steps to denoise the image whilst emphasizing the edges of the hydrogel walls for extracting either the pores or hydrogel walls features is explained. Finally, the information of hydrogel porosity and heterogeneity is presented in form of pore size distribution, spatial contours maps and kernel density dot plots. The obtained results reveal that a non-parametric kernel density plot effectively determines the spatial heterogeneity and porosity of the hydrogel.

Image analysis method for heterogeneity and porosity characterization of biomimetic hydrogels

This work presents an image processing procedure for characterization of porosity and heterogeneity of fully hydrated hydrogels based on the analysis of cryogenic scanning electron microscopy (cryo-SEM) images. An algorithm consisting of different filtering, morphological transformation, and thresholding steps to denoise the image whilst emphasizing the hydrogel fibres edges for extracting the pores features is explained. Finally, the information of hydrogel porosity and heterogeneity is presented in form of pore size distribution, spatial contours maps and kernel density dot plots. The obtained results reveal that a non-parametric kernel density plot effectively determines the spatial heterogeneity and porosity of the hydrogel.

Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

Geopolymers are zeolites like structures based on hydrated aluminosilicates units of SiO4 and AlO4. These units, known as poly(sialate), poly(sialate)-siloxo or poly(sialate)-disiloxo are chemically balanced by the group I cations of K+, Li+, or Na+. Simultaneously, the chemical reaction of formation, known as geopolymerization, governs the orientation of the unit, generating mesoporous structures. Multiple methods can be used for pore structure and porosity characterization. Among them, nuclear magnetic resonance (NMR) relaxometry allows the detection of the porous structure in a completely nonperturbative manner. NMR relaxometry may be used to monitor the relaxation of protons belonging to the liquid molecules confined inside the porous structure and, thus, to get access to the pore size distribution. This monitoring can take place even during the polymerization process. The present study implements transverse relaxation measurements to monitor the influence introduced by the curing time on the residual liquid phase of geopolymers prepared with two different types of reinforcing particles. According to our results, the obtained geopolymers contain three types of pores formed by the arrangement of the OH− and Si groups (Si-OH), Si-O-Si groups, Si-O-Al groups, and Si-O rings. After 48 days, the samples cured for 8 h show a high percentage of all three types of pores, however, by increasing the curing time and the percentage of reinforcing particle, the percent of pores decrease, especially, the gel pores.

The Effect of Additional Zinc Oxide to Antibacterial Property of Chitosan/Collagen-Based Scaffold

The bone scaffold is susceptible to infection in its application due to the bacteria that often appear on the surface. To prevent this phenomenon, the scaffolds need to be modified in order to provide antibacterial properties. In this study, the bone scaffold was fabricated from chitosan-collagen with the addition of zinc oxide as an antibacterial agent. There were four variables of the amount of zinc oxide added to the scaffold: 0%, 1%, 3%, and 5%. The method used was Thermally Induced Phase Separation (TIPS). From this study, a porous scaffold with a rough surface was obtained. SEM image of the scaffold showed that more zinc oxide caused smaller pore and lower porosity. Characterization with FTIR proved that the scaffold obtained from this process has the same functional group as chitosan and collagen. The DSC-TGA curve confirmed that the heating process performed on dehydrothermal treatment (DHT) did not cause degradation of the scaffold because chitosan and collagen have higher degradation temperatures than DHT temperatures. In addition, this study also proved that the addition of zinc oxide had successfully provided the scaffold with antibacterial properties in which the protection against bacteria was related to the amount of zinc oxide in direct proportion.