Diffusion Foundations and Materials Applications Vol. 36

Abstract: South Kalimantan-Indonesia is known to have extensive peatlands reaching 15% of a total peatland in Kalimantan. Due to that peat land water is mostly found and claim as abundant water sources. However, based on quality, peat land water has poor characteristic with high natural organic matter content. Therefore, peat water treatment is necessary to treat using effective method such as hybrid conventional filter and membrane using hollow fibre PVDF-TiO₂/SBE. This study aims to investigate the variation of media filter thickness and filtration pressure of hollow fibre (HF) PVDF-TiO₂/SBE membrane peat water treatment by filtration pre-treatment and HF membrane ultrafiltration. HF PVDF-TiO₂/SBE membrane was prepared by wet spinning method using spinneret set up. Hybrid process was divided into two steps: 1) conventional filter as pre-treatment and 2) HF ultrafiltration membrane under cross flow system. The filter media was used in this work is silica sand and activated carbon with varied thickness 30:10 and 10:30 cm. The HF membrane structure was analysed via scanning electron microscopy (SEM) to investigate the membrane morphology. The results show the fabricated HF membrane has a finger like-sponge sandwich structure morphology. In addition, 30:10 cm (silica sand: activated carbon) thickness exhibits TDS and turbidity removal of 92.18 and 61.37%, respectively as conventional filter pre-treatment. In other hand, HF membrane successfully removed TDS and turbidity of peat water up to 98.68% and 92.41% at 2 bar of filtration pressure. The highest permeate flux of HF membrane conducted of 13.055 Kg.m^-2.h^-1 at 3 bar. Conclusion of this work is the peat water treatment using activated carbon: silica filtration pre-treatment and HF membrane ultrafiltration can provide clean water with maximum turbidity and TDS removal.

Abstract: The most significant pollutant produced from agricultural industry in Kalimantan, Indonesia is Palm Oil Mill Effluent (POME). Due to the high levels of suspended particles and organic matter, POME has become a brownish color with high turbidity, color, chemical oxygen demand, and oil and grease content. To recycle the POME wastewater as clean water, these pollutants must be eliminated. In this study, we compare the effectiveness of hollow fiber (HF) and flat sheet (FS) membrane to remove total dissolved solid (TDS) and turbidity from POME with varied filtration pressure. HF and FS membrane were prepared from PVDF and nylon66 polymer, respectively. The PVDF HF membrane was modified using TiO₂ and SBE (spent bleaching earth) to improve HF membrane properties to maintaining fouling. Meanwhile, FS membrane was added by pectin to increase the hydrophilic properties. Overall membrane’s morphology was determined by Scanning Electron Microscopy (SEM) to investigate the membrane structure. Both of HF and FS membrane were operated via ultrafiltration (UF) under cross flow system. The filtration pressures were varied at 1-3 bar and followed by flux and rejection evaluation. The results show both HF and FS membranes has stability flux. In addition, TDS rejection up to 25% while turbidity is excellent high over 95% for all membranes. The fabrication HF membrane has finger like-sponge structure and FS membrane exhibits sponge asymmetric structure. Overall, all membranes perform highest water flux (FS membrane) while highest rejection conducted by HF membrane for POME wastewater treatment.

Abstract: The high difference in surface tension between the filler and the polymer often constrains membrane compatibility. To reduce the surface tension, organosilane such as GPTMS is usually used to improve miscibility. In this study, GPTMS was introduced to produce lignin-GPTMS (LG) and lignosulfonate-GPTMS (LsG). The modification was done by reacting lignin and lignosulfonate with GPTMS using ethanol as the media. The product was characterized using Fourier Transform InfraRed (FTIR), X-ray Diffraction (XRD), Particle Size Analyzer (PSA), Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) and microscope. The success of functionalization was shown in FTIR spectra with the vibration of Si-O at 1034 cm^-1 and 528 cm^-1. The XRD analysis presents that the filler material has an amorph and crystalline structure. The functionalization using a 2:1 ratio increases zeta potential absolute and particle size due to the silane being a bridge and making a larger macromolecule. For a ratio of 1:1, a higher organosilane compound results in breaking siloxane linkages and making smaller molecules. Mixed LG and LsG into PVDF membrane conducted to analyze filler compatibility. The sulfonation and functionalization of GPTMS increase the compatibility of lignin in PVDF membrane with the best homogeneity achieved by a membrane with the addition of LsG 1:1.

Abstract: Gold nanoparticles (AuNPs) have been successfully synthesized using aqueous sambiloto (Andrographis Paniculata Ness) leaf extract as a reducing agent. This method of synthesizing nanoparticles is called biosynthesis. Characterization was carried out using various techniques including UV-Vis, FTIR, and TEM. The results showed that the optimal synthesis ratio, i.e., AuCl₃ solution : sambiloto leaf extract, was 30 µl : 10 ml with a synthesis rate of 0.159 a.u./h. The characteristic of the gold nanoparticles synthesized is that the surface Plasmon resonance (SPR) wavelength is 529.00 nm; it was stable after 4 hours of synthesis and stayed until 24 hours at an SPR wavelength of 527.00-531.50 nm. The functional groups formed include O-H, aliphatic C-H, C=O stretch, aromatic C=C stretch, and C-O stretch. The size of the nanoparticles is in the range of 1-20 nm.

Abstract: Due to its notable characteristics, porous silicon (PSi) has become the main focus in silicon upgrades for optoelectronics, medical, and sensor applications. Here, successful vertical photoelectrochemical fabrication of PSi based on crystalline silicon n-type wafers with orientation (100) has been accomplished. Silicon surfaces were anodized for 10 min in a solution of hydrofluoric acid and ethanol at a ratio of 1:3 and a current density of 4 mA/cm² under laser illumination. Illumination sources were red, green, and purple laser beams with energies of 1.91 eV, 2.33 eV, and 3.06 eV, respectively, conducted to observe the effects on PSi microstructures and optical properties. The pores formed on the silicon surface were characterized via SEM, XRD, FTIR, and UV-Vis DRS Spectrophotometer. SEM analysis showed pore size distributions of 2.130, 3.353, and 1.078 mm for PSi samples with red, green, and purple lasers, respectively. XRD investigation revealed diffraction angles of 33.14° and 69.47° belonging to (211) and (422) planes, respectively, corresponding to the PSi. For samples of silicon and PSi with red, green, and purple lasers, the crystallite size and crystallinity were 168.55 nm and 44.80%, 25.02 nm and 17.12%, 29.19 nm and 23.56%, and 145.05 nm and 35.17%, respectively. FTIR observation confirmed that the PSi surface contained chemical bonds of Si-Si, Si-H, Si-H₂, Si-O-Si, and C=O. UV-Vis DRS examination revealed the reflectance spectrum oscillation, indicating that lasers caused pore formation in PSi with bandgap energies of between 1 and 2 eV.

Abstract: Almost no product is made today without the use of composite materials, which have demonstrated their value over time in a variety of applications. Examples include household products, automobiles, oil and gas stations and spacecraft. Instead of using timber, leaves will be used to create a solid material. The goal of this study is to identify the distinguishing features of composite materials made from dates palm waste, as well as the overall effects on the properties when changing the mixture's proportions and the amount to which those materials are vulnerable to outside influences. It also aims to identify the best material that can be produced and used in home furnishings, manufacturing, architectural design, practical applications, and other science-related fields. This project will address the use of natural fibers from dates palm waste and some other materials to convert them into a strong, lightweight, low-cost composite material to replace wood, aluminum, synthetic fibers, and other materials in industries and uses. It will also explore the manufacturing processes, testing methods, and the outcomes of comparing it with other materials. The UHU (adhesive) matrix has the lowest hardness value compared to others. Structure tests show composites' internal composition; it plays an important role in understanding the properties of composites. The water absorption test demonstrates the duration required for composites to become saturated with water, with optimal results falling within the range of 13 to 24 hours for saturation.

Abstract: In the present study, a quasi-static compression test and impact test are carried out on a Polycarbonate plate with thickness of 2.66 mm and an effective diameter of 205 mm. The impact test is carried out on a pneumatic gun using a hardened truncated cone projectile of mass 25.8 g at different velocities. On the other hand, a servo mechanical universal testing machine with a 50 kN capacity is used to carry out the quasi-static compression test at a speed of 2 mm/min adopting an indenter of truncated nose shape. The Dynamic Enhancement Factor, or DEF, is computed as the ratio of quasi-static perforation energy to impact perforation energy. The measured DEF in the present study is compared with previously published results for metal and polycarbonate. Also local deformation of the plate after perforation is compared for both quasi-static test and dynamic test.