This study aims to comprehensively investigate the current advances in water treatment technologies for the elimination of heavy metals using biomass-based adsorbents. The enhancement of adsorption capacity in biomass materials is achieved through surface modification, which increases their porosity and surface area. The study therefore focuses on the impact of different surface modification techniques on the adsorption capacity, as well as the evaluation of adsorptive removal techniques and the analysis of various isotherm and kinetics models applied to heavy metal contaminants. The utilization of kinetic and isotherm models in heavy metal sorption is crucial as it provides a theoretical background to understand and predict the removal efficiency of different adsorbent materials. In contrast to previous studies, this research examines a wide range of adsorbent materials, providing a comprehensive understanding of their efficacy in removing heavy metals from wastewater. The study also delves into the theoretical foundations of the isotherm and kinetics models, highlighting their strengths, limitations, and effectiveness in describing the performance of the adsorbents. Moreover, the study sheds light on the regenerability of adsorbents and the potential for their engineering applications. Valuable insights into the state-of-the-art methods for heavy metal wastewater cleanup and the resources required for future developments were discussed.

Due to the increasing world population and environmental considerations, there has been a tremendous interest in alternative energy sources. Hydrogen plays a major role as an energy carrier due to its environmentally benign nature. The combustion of hydrogen releases water vapor while it also has a vast industrial application in aerospace, pharmaceutical, and metallurgical industries. Although promising, hydrogen faces storage challenges. Underground hydrogen storage (UHS) presents a promising method of safely storing hydrogen. The selection of the appropriate cushion gas for UHS is a critical aspect of ensuring the safety, efficiency, and reliability of the storage system. Cushion gas plays a pivotal role in maintaining the necessary pressure within the storage reservoir, thereby enabling consistent injection and withdrawal rates of hydrogen. One of the key functions of the cushion gas is to act as a buffer, ensuring that the storage pressure remains within the desired range despite fluctuations in hydrogen demand or supply. This is achieved by alternately expanding and compressing the cushion gas during the injection and withdrawal cycles, thereby effectively regulating the overall pressure dynamics within the storage facility. Furthermore, the choice of cushion gas can have significant implications on the performance and long-term stability of the UHS system. Factors such as compatibility with hydrogen, cost-effectiveness, availability, and environmental impact must be carefully considered when selecting the most suitable cushion gas. The present study provides a comprehensive review of different types of cushion gases commonly used in UHS, including nitrogen, methane, and carbon dioxide. By examining the advantages, limitations, and practical considerations associated with each option, the study aims to offer valuable insights into optimizing the performance and reliability of UHS systems. Ultimately, the successful implementation of UHS hinges not only on technological innovation but also on strategic decisions regarding cushion gas selection and management. By addressing these challenges proactively, stakeholders can unlock the full potential of hydrogen as a clean and sustainable energy carrier, thereby contributing to the global transition towards a low-carbon future.

Underutilization of some wood species can be largely attributed to a dearth of scientific information. Therefore, identifying the acoustic characteristics of lesser used wood species such as Boscia angustifolia and Albizia adianthifolia wood is expected to encourage their use in acoustic applications. Thus, studying their acoustic properties and the relationship among these properties will help reveal their use potential for acoustic purposes and also highlight possible predictor variable(s) for other acoustic parameters in wood acoustics. This study aimed at measuring the acoustic properties of B. angustifolia and A. adianthifolia wood and investigating the correlation among these properties. Three trees of each species were felled, and a total of 270 wood samples of 20 by 20 by 300 mm³ were collected. The samples were conditioned before acoustic measurement. The longitudinal free vibration method was adopted to measure the acoustic properties. Some of the mean acoustic results obtained for B. angustifolia and A. adianthifolia wood were 835.89 Hz, 3,657.51 m/s, 0.008, 13.59 GPa, 935.39 m⁴ kg⁻¹ s⁻¹, and 807.78 Hz, 3,542.66 m/s, 0.009, 12.65 GPa, 731.75 m⁴ kg⁻¹ s⁻¹, respectively, for fundamental sound frequency (FF), velocity of sound (V), damping factor (tan δ), specific dynamic modulus of elasticity (Es), and acoustic conversion efficiency (ACE). The correlation of FF with tan δ was negatively significant (−0.59), while it was positively significant with Es and ACE (0.99 and 0.74). This study found the two wood species suitable for making frame boards only and highlights sound frequency and velocity of sound as the major predicting acoustic variables for measuring good acoustic wood.

In the era of environmental consciousness, the demand for highly efficient materials and technologies capable of producing hydrogen is at an all-time high. One promising solution to this challenge lies in harnessing the power of biological hydrogen production, complemented by the integration of nanomaterials including carbon-based materials and transition metals. Various methods employed in biological hydrogen production, including bio-photolysis, dark and photo fermentation, and anaerobic digestion coupled with nanomaterials, have garnered significant scientific and technological attention. In this chapter, we delve into the different methods of hydrogen production from biological sources, exploring their potential when combined with nanomaterials. The advantages and applications of these methods are thoroughly discussed, shedding light on their efficacy and efficiency in hydrogen production. By offering a broad view of modern preparation methods and their practical applications, this assessment paves the way for rapid development in the field. Embracing the synergy between biology and nanomaterials, this chapter presents a compelling argument for the integration of these technologies in the quest for sustainable hydrogen production. We hope that this study catalyzes further advancements, propelling us toward a greener and more prosperous future. <!----> <!----> <!----> <!---->