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Nanotechnology has many advantages, and its applications are spread to every field, from engineering to medicine and space to agriculture. Owing to the immense advantages of nano-size particles, nano-based materials are widely applied in wastewater treatment. These nanomaterials are developed and utilized in different sizes, shapes, and chemical compositions. These nanomaterials are characterized by their unique physical, chemical and biological properties. Besides the immense benefits of nanomaterials, they also have few environmental implications. This chapter presents the pros and cons of nanomaterials and their implications on the environment. Further, the effect of various nanomaterials on the aquatic environment, including the behaviour and toxicity on the aquatic ecosystem, is discussed. Finally, future directions to minimize the toxic effect of nanomaterials on the aquatic ecosystem and the need for improvement in the nanomaterials are presented.&nbsp

Every year, considerable amounts of waste materials are produced and landfilled due to the construction, maintenance, and rehabilitation of road pavements. As a result, the road pavement sector is under increasing societal pressure to mitigate the negative environmental impacts arising from these construction and maintenance activities. Among other initiatives, the conversion of waste materials into alternative raw materials for road paving applications has been proposed to lower the extraction of virgin raw materials. As the market for recycled materials, including plastic recyclates, is becoming more complex, it is increasingly more difficult to quantify the potential environmental benefits of using these materials for road construction. A systematic appraisal method to assess the extent to which such practices are indeed environmentally beneficial is life cycle assessment (LCA). After presenting a condensed overview of the plastic waste management system and how plastic recyclates can be used in asphalt mixtures, this chapter offers an overview of the LCA methodology, including its main phases, elements, and modeling approaches. This is followed by a brief description of how the LCA methodology has been embraced by the pavement community, and the presentation of concepts, methodological, and operational aspects related to the application of LCA to waste management systems. A conceptual example of a consequential LCA case study is then presented to investigate the potential environmental consequences of utilizing plastic recyclates in place of virgin aggregates in the production of asphalt mixtures. This chapter then concludes with current challenges and open issues related to advanced LCA modeling aspects and opportunities for increasing the use of plastic recyclates in asphalt pavements. While the presented fundamentals of LCA modeling of recycled materials and pavements will be valuable for young researchers and practitioners, the explanation of consequential, and attributional LCA modeling approaches can provide interesting insights for advanced users.

Aerogel is a special type of porous material with many outstanding physical and chemical properties, such as low density, high porosity, high surface area, and adjustable surface chemistry. Thanks to the latest advances in the synthesis of different types of aerogels, the feasibility of this porous material in several applications has been widely explored. In a variety of high performance applications, aerogels have received much attention as an adsorption medium that removes a variety of environmental and human health pollutants. Although the performance of aerogels in environmental sanitation is encouraging, some shortcomings of aerogels, such as complex drying process, mechanically fragile structure and processing costs, have also been taken into account and have been taken into account been determined in some studies. Degree of relief. This review article aims to describe the synthesis and processing of aerogels and their latest applications in air purification, such as carbon dioxide capture and VOC removal, as well as applications in the treatment of air, water, including oils and toxic organic compounds and heavy metals ion removal.

Abundant CO2 emissions from industries and the transportation sector cause an alarming threat to the planet due to overwhelming concerns over CO2 induced climate change. To resolve this tremendous environmental pollution, the long-term solution for CO2 mitigation exists in the conversion of CO2 into value-added products through catalysis. Among several catalysts, metal organic frameworks (MOFs) are one of the remarkable candidates for CO2 conversion into fuels and chemicals. The MOFs are molded with robust structures, high porosity, high potential of CO2 adsorption, maximum atom utilization due to high dispersion and isolation of active sites of MOFs, tunability of the metal nodes, organic ligands, etc. MOFs have been implemented for several CO2 conversion processes such as cycloaddition of CO2 to epoxides, photocatalytic CO2 reduction, electrocatalytic CO2 reduction, hydrogenation, and others. These processes convert CO2 into products like cyclic carbonates, alkyl formate, formic acid, ethanol, methanol, methane, CO, and others. This study strived to explain elaborately the formation of fuels and chemicals through different catalytic processes using MOFs. Detailed reaction conditions, catalyst chemistry, reaction mechanisms, and formation rates for alkyl formate, formic acid, methanol, ethanol, CO, and methane have been critically analyzed in present study.

Recent years have witnessed rise in the production of microbial fermentation of metabolites and proteins for industrial applications. The innovative method aims to improve the conventional batch fermentation and the separation. Furthermore, the idea of downstream processing of the target product enhances the efficiency of the overall process and makes it cost-effective and eco-friendly. Even though being cost-effective and eco-friendly, the process faces challenges in commercial applications. When the concentration of the final product/by-product reaches a certain level, feedback inhibition is a common problem encountered in the fermentation process. Excessive accumulation of end products/by-products in culture also inhibits cell growth and secretion of target metabolites. The fermentation results in the production of antibiotics, fungal metabolites, and amino acids, which come with serious inhibition problems. Hence, to mitigate such problems and enhance fermentation performance, extractive fermentation via in situ ion exchange adsorptive technique can be incorporated. The present review highlights the advances and suggests the strategies to resolve the inhibition problems using extractive fermentation via internal, external, and dispersed resin systems. Furthermore, methods for synthesis of resins are discussed and adsorption mechanism of ion exchanges is also elaborated.

Malaysian oil palm industry produces a significant amount of oil palm residue as solid wastes. These solid wastes are comprised of oil palm residue which contains the stem, fronds from the farms, empty fruit bunch (EFB), mesocarp fibre (MF), and palm kernel shell (PKS) from the oil palm–processing factories. These residues are not successfully reused for other purposes, and the current dumping methods can possibly trigger unfavourable effects to the environment. As oil palm residues are a readily available waste biomass, it has a high potential to be converted into valuable energy-derived products. Hydrothermal carbonization (HTC), which is a thermochemical process, is a method used to treat biomass to produce hydrochar under hot-compressed water. Oil palm residues (palm leaves, palm fronds, and palm shell) were used as the feedstock for producing carbonaceous hydrochar. The key objective of this study is to examine the effect of the reaction temperature, residence time, and acid catalysts on the HTC process. HTC of oil palm residues was optimized at different operating temperatures from 140 to 300 °C and different reaction times between 30 and 240 minutes with a biomass-to-water ratio of 1:10 wt%. Acid catalysts such as citric acid and ascorbic acid were used for the HTC process. The hydrochar produced is further characterized using heating value and elemental and Fourier transform infrared (FTIR) analysis. The yield of hydrochar reduces with the rise of temperature and time but it increases in the presence of acid catalysts. The carbon content of hydrochar is observed to be between 44.36 and 49.50%. The FTIR analysis showed that a high intensity at 1423 cm−1 indicates a high content of lignin and cellulose in the hydrochar. A considerable decrease in the H/C and O/C atomic ratio shows that the dehydration and decarboxylation take place during the HTC process.

Due to the rising demands of cleaner fuels (free from sulfur), most of the oil industries are implementing the process of the desulfurization. In present work, the extractive desulfurization (EDS) efficiency of binary solvents composed as mixtures of bronsted acidic ILs ([Hnmp][HSO4] and [Hnmp][H2PO4]) and nonvolatile organic solvent known as dimethylformamide (DMF), is investigated for the model fuel oil (containing thiophene as S-compounds). The main advantages of using binary solvents are; low viscosity of extractant and reduced cost of the process. Effect of key operating parameters such as temperature, time, multiple steps, initial S-content in oil and oil:binary solvent (w/w) ratio on the S-removal efficiency is examined. Based on the obtained results, optimal 40 °C and 45 min are chosen as operating temperature and extraction time, respectively. Almost 95% of S-removal (decrease from 500 to 22 ppm and 28 ppm) is obtained through five steps extraction for both binary solvents, also these exhibited remarkable extraction performances for different initial S-content of fuel oil. The recyclability and reusability of solvents are investigated, where it is observed that binary solvent has reasonable effectiveness when reused for four times. The solvents can also be regenerated without undergoing any change in the actual structure of ILs. This study shows that EDS based on the binary solvents can be a suitable option to produce the cleaner fuel oils.

Nanotextiles are emerging engineered materials for textile industry. However, the exposure of these materials possesses risks to health, environment, and sustainability. It has been observed that nanosized materials from commercial textiles are released during their washing and/or abrasive exposure, which cause their accumulation in water bodies and soil. Production of biocidal nanotextiles is also reported in the literature, which can destroy the aquatic echo system when dumped into waters. The acquisition of data on emissions and environmental concentrations of nanoparticles (NPs) of the nanotextiles is of utmost importance. There is a lack of sustainable separation procedures and analytical methodologies to determine the concentrations of nanomaterials. Moreover, quantification of fate of nanotextiles is also important as currently some of the major sinks of the nanotextiles are sewage sludge, wastewater, air and soil, which contribute to the environmental degradation. This chapter highlights the application of nanomaterials in textiles, release of nanomaterials from textiles, analytical procedures for determination of NPs from water, their toxicity, and threats to public health and environment.

Nanomaterials have attained significant applications in textile materials. Nanomaterials provide several functional, physical, chemical, mechanical, and electrical properties to the textiles. These characteristics make textile materials suitable for a variety of applications. Nanotextile materials have been tested for applications in corrosive environments, fire protection, UV absorption, antibacterial, and antiodor effect, water repulsion, shape memory supercapacitors, triboelectric nanogenerators, drug delivery, electrocardiography, electroencephalography, electrooculography, electromyography, bioimpedance, and several other applications. The demand is also increasing because of convenient and mobile use of wearable textiles. Based on the application trends, it may be safe to assume that nanotextile materials shall dominate the textile industry in future. This chapter highlights the important properties of nanomaterials for textiles, discusses applications, trends and prospects of nanotextile materials.

Post-combustion Carbon dioxide (CO2) capture (PCC) via amine absorption-stripping is an evolving technology towards mitigation of CO2 emissions. One of the major challenges in the technology development is the suitability of the solvent. Under the process operating conditions, irreversible reactions occur, thereby degrading the amine. The consequences of amine degradation are inevitable. The degradation products are harmful to the environment, increase the corrosion in the process equipment, cause fouling and ultimately make the process inefficient, hazardous and expensive. Monoethanolamine (MEA) is the benchmark solvent used and tested at industrial level for CO2 capture because of its high absorption rate and capacity to capture CO2 as well as medium to high resistance against oxidative and thermal degradation. This review reports degradation of MEA under process operating conditions, which includes up-to-dated list of degradation products, degradation kinetics and degradation pathways. Furthermore, degradation inhibition, computational studies, corrosivity as well as environmental concerns regarding the emissions of amine degradation products are critically reviewed. The objective of study is to provide researchers with a comprehensive knowledge on degradation of MEA, ways to reduce degradation, corrosion inhibition and understanding of environmental concerns for development of models for better understanding of behaviour of MEA and knowledge gaps.

Physical and thermodynamic properties of physical or chemical solvents are of utmost importance for mass and heat transfer calculations, process design and solvent regeneration. In recent times, machine learning has attracted interest for applications in several fields of engineering sciences. The ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF6] is an emerging solvent for CO2 capture. In this study, three Gaussian process regression (GPR) models - the Matern 5/2 GPR model, rational quadratic GPR model, squared exponential GPR model - and one support vector machine (SVM) model (the nonlinear SVM)– are developed for predicting CO2 solubility, density, viscosity and molar heat capacity of [Bmim][PF6]. Detailed statistics of each model and comparative analyses between the models and their predicted results with experimental results is highlighted.