Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na2SiO3 used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m3. The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels.
This research involved carrying out a unique micro-mesoporous carbon particle incorporation into P84 co-polyimide membrane for improved gas separation performance. The carbon filler was prepared using a hard template method from zeolite and known as zeolite-templated carbon (ZTC). This research aims to study the loading amount of ZTC into P84 co-polyimide toward the gas separation performance. The ZTC was prepared using simple impregnation method of sucrose into hard template of zeolite Y. The SEM result showing a dispersed ZTC particle on the membrane surface and cross-section. The pore size distribution (PSD) of ZTC revealed that the particle consists of two characteristics of micro and mesoporous region. It was noted that with only 0.5 wt% of ZTC addition, the permeability was boosted up from 4.68 to 7.06 and from 8.95 to 13.15 barrer, for CO2 and H2 respectively when compared with the neat membrane. On the other hand, the optimum loading was at 1 wt%, where the membrane received thermal stability boost of 10% along with the 62.4 and 35% of selectivity boost of CO2/CH4 and H2/CH4, respectively. It was noted that the position of the filler on the membrane surface was significantly affecting the gas transport mechanism of the membrane. Overall, the results demonstrated that the addition of ZTC with proper filler position is a potential candidate to be applicable in the gas separation involving CO2 and H2.
Green diesel as a second-generation biofuel has received enormous attention owing to the huge demand for renewable fuel for addressing the net zero target in 2050. This study examines the development of green diesel research through a bibliometric analysis. The state-of-the-art green diesel research is studied based upon 1285 documents (1153 articles and 132 reviews) retrieved from the Scopus database related to the used keywords. The analysis focused on three categories: publication outcomes, most cited papers, and research area identification. The VOSviewer and RStudio (bibliometrix) were applied to analyse the data, rationalized within the framework of author, affiliation, country, citation analysis, cross-dimensional keyword analysis, research streams, and research gaps. The general result of the study highlighted a continuous incline in article numbers classified into three stages: initiation, exploration, and elevation. Those articles were mainly published in bioenergy-themed journals, including Fuel, Energy & Fuels, and Renewable and Sustainable Energy Reviews. Taufiq-Yap Yun Hin is the highest contributor with 41 articles, and Fuel published 110 articles. The rapid growth of green diesel was also inferred by the extensive spread of research maps worldwide. Amid those swift developments, the state of the art on green diesel through bibliometric analysis is not available to the best of our knowledge as far. Subsequently, this review aims to display the state of the art, research gap, and future forecast of green diesel research.