Biosorption, a sustainable technology, utilizes living or non-living organism and their derivative as sorbents for the removal of heavy metals from wastewater. This review explores the mechanisms and applications of biosorption in addressing environmental challenges posed by heavy metal contaminants. Pretreatment methods enhance biosorbent performance by modifying cell wall structures through physical and chemical alterations, increasing metal binding capacity. Immobilization techniques like cell entrapment and cross-linking improve biosorbent stability and reusability in continuous systems, offering controlled particle size and ease of biomass separation. Differential Scanning Calorimetry assesses biosorbent thermal stability, providing insights into performance under varying conditions. Non-living microorganisms present advantages for biosorption, including resilience to toxic wastes and extended storage capabilities. Economic considerations are crucial when evaluating biosorbent modifications for enhanced performance. The review show that biosorption using microbial biosorbents is a versatile and efficient method for heavy metal removal from wastewater, with applications in environmental remediation and sustainable water treatment practices. Future research should focus on novel biosorption strategies and optimization of existing techniques to effectively combat heavy metal pollution.

Each student has their own characteristics and way of doing 3D geometric thinking. The way of thinking that students do influences the resulting understanding of the concept of 3D geometry. Therefore, this study aims to investigate students' geometric thinking based on the level of achievement of students in completing the 3D geometric thinking ability test (3D GTA). This study uses an exploratory case study design. The participants who voluntarily participated were 33 junior high school students (14 boys, 19 girls) in one of the schools in Indramayu Regency, Indonesia. Data obtained from the process of observation, tests, interviews, and documentation were analyzed qualitatively using Atlas. ti 8 software. The findings revealed that students with low 3D GTA achievements experienced difficulties in representing and calculating the surface area and volume of 3D shapes. In addition, students with moderate 3D GTA achievements experienced difficulties in representing 3D shapes but were able to translate 2D shapes from 3D shapes. Furthermore, students with high 3D GTA achievements experienced difficulties in calculating the surface area and volume of 3D shapes, but were able to use appropriate formulas and were able to interpret the comparisons of 3D geometric shapes well. The results of this study have implications for helping teachers identify student characteristics in understanding the concept of 3D geometry and connections with 2D geometry.

Refinery off-gas is one of the major causes of air pollution, where its reuse, through channeling into other plant setups to recover some of its constituent gases (via a steam reforming technique), is described as one of its best handling measures. A nominal off-gas containing 2.898% hydrogen (H2), 83.794% methane, 1.505% carbon dioxide, 1.103% nitrogen, 10.6% sulfur and 0.1% argon was fed to a plant to produce 37.52 kg of H2. To lift the performance of the multiple interconnected process units enhancing the generation of H2, temperature and pressure in the reactors were manipulated against the heat duty and H2 yield, where it was found that the two dependent variables are sensitive to changes made during Aspen Plus sensitivity analysis. Replacing some process units also shows significant improvement in the recovery of H2 gas. Adequate control of the synthesis process as exemplified in this work, will lead to smooth realization of the target end-product which is of high economic value; basically, looking at its potential for the manufacture of other useful materials it is already known for. Received: 10 May 2023 | Revised: 16 June 2023 | Accepted: 30 June 2023 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement The data that supports the findings of this study is openly available with zannahabba154@gmail.com, and would be shared upon request via email.

This study aims to produce activated carbon (AC) from different biomass sources using chemical activation; characterize the AC using Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), proximate and ultimate analysis; and compare the results from the AC produced. The biomass blends of rice husk & groundnut shell (RH-GS), cocoa nut shell & saw dust (CS-SD) and sugar cane bagasse & banana peel (SB-BP) were used for the preparation of AC. The samples were first characterized using proximate and ultimate analysis, SEM, and FTIR spectroscopy. The results of the BG-SD sample characterization showed that the blend produced the best results in terms of absorptive capacity. It is suggested that surface area difficulties with the ACs be investigated in order to improve their porosity and adsorption capacities.

Awareness of the need to protect the environment and people's health has led to an intensification of concerns for obtaining sustainable products and processes. Toxic waste created during the production and use of synthetic dyes has an impact on both human and environmental health. As a result, natural dyes are more secure and safer than synthetic dyes. This study is significant because it has the potential to help develop sustainable and environmentally friendly textile dyeing techniques. In this study, a natural dye was successfully extracted from orange peel (Citrus recticulata Rutaceae) which was applied on textile fibre and was found to be partly effective for eco-friendly dyeing applications. The extracted dye does not have a good wash fastness, which is the ability of the fabric to retain its colour after washing. This weakness is demonstrated by carrying out a Fourier transform infrared (FTIR) analysis where the potential binding mechanisms between the dye and the textile fibres was revealed. Different functional groups can interact with the fibre’s functional groups, affecting the dye's affinity for the fabric and its overall colour fastness properties. Findings show that dyes from orange peels showed promise in this study, but need to be improved further. Therefore, the study suggests that further research is needed to optimize the dyeing process and improve the fabric's resistance to washing and other environmental factors.