This study aims to improve the quality of fuel with high calorific value namely Sfuel - a commercial high-quality refuse-derived fuel (RDF) from hazardous waste via modifying the process design and operating parameters of thermal conversion process. The study analyses key parameters of RDF quality, such as calorific value and heavy metal content, before and after process modifications based on the combination of experimental and simulation using Aspen Plus. In this study, the temperature and pressure of the simulation system are varied from 100 to 700 °C and from 1 to 5 bar, respectively. Findings indicate that there are a total of eleven heavy metals and 179 volatile compounds in the "Sfuels". The quality of the targeted product is greatly improved by the metal evaporation at high temperatures and pressures. However, the calorific value of RDF significantly decreases at 700 °C due to a large amount of the carbon content being evaporated. Although the carbon content at high temperatures is significantly lost, the heat from the vapour stream reactor outlet, which is reused to preheat the nitrogen gas stream supplied to the system, reduces energy consumption while improving the thermal conversion efficiency of the system. Besides, low pressure along with high temperature are not the optimal conditions for quality Sfuels improvement by thermal conversion. Results also indicate that electric heating is more economically efficient than natural gas heating.
Incense sticks ash is one of the most unexplored by-products generated at religious places and houses obtained after the combustion of incense sticks. Every year, tonnes of incense sticks ash is produced at religious places in India which are disposed of into the rivers and water bodies. The presence of heavy metals and high content of alkali metals challenges a potential threat to the living organism after the disposal in the river. The leaching of heavy metals and alkali metals may lead to water pollution. Besides this, incense sticks also have a high amount of calcium, silica, alumina, and ferrous along with traces of rutile and other oxides either in crystalline or amorphous phases. The incense sticks ash, heavy metals, and alkali metals can be extracted by water, mineral acids, and alkali. Ferrous can be extracted by magnetic separation, while calcium by HCl, alumina by sulfuric acid treatment, and silica by strong hydroxides like NaOH. The recovery of such elements by using acids and bases will eliminate their toxic heavy metals at the same time recovering major value-added minerals from it. Here, in the present research work, the effect on the elemental composition, morphology, crystallinity, and size of incense sticks ash particles was observed by extracting ferrous, followed by extraction of calcium by HCl and alumina by H2SO4 at 90-95 °C for 90 min. The final residue was treated with 4 M NaOH, in order to extract leachable silica at 90 °C for 90 min along with continuous stirring. The transformation of various minerals phases and microstructures of incense sticks ash (ISA) and other residues during ferrous, extraction, calcium, and alumina and silica extraction was studied using Fourier transform infrared (FTIR), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). DLS was used for analyzing the size during the experiments while FTIR helped in the confirmation of the formation of new products during the treatments. From the various instrumental analyses, it was found that the toxic metals present in the initial incense sticks ash got eliminated. Besides this, the major alkali metals, i.e., Ca and Mg, got reduced during these successive treatments. Initially, there were mainly irregular shaped, micron-sized particles that were dominant in the incense sticks ash particles. Besides this, there were plenty of carbon particles left unburned during combustion. In the final residue, nanosized flowers shaped along with cuboidal micron-sized particles were dominant. present in If, such sequential techniques will be applied by the industries based on recycling of incense sticks ash, then not only the solid waste pollution will be reduced but also numerous value-added minerals like ferrous, silica, alumina calcium oxides and carbonates can be recovered from such waste. The value-added minerals could act as an economical and sustainable source of adsorbent for wastewater treatment in future.
In low concentration, fluoride is considered a necessary compound for human health. Exposure to high concentrations of fluoride is the reason for a serious disease called fluorosis. Fluorosis is categorized as Skeletal and Dental fluorosis. Several Asian countries, such as India, face contamination of water resources with fluoride. In this study, a comprehensive overview on fluoride contamination in Asian water resources has been presented. Since water contamination with fluoride in India is higher than other Asian countries, a separate section was dedicated to review published articles on fluoride contamination in this country. The status of health effects in Asian countries was another topic that was reviewed in this study. The effects of fluoride on human organs/systems such as urinary, renal, endocrine, gastrointestinal, cardiovascular, brain, and reproductive systems were another topic that was reviewed in this study. Different methods to remove fluoride from water such as reverse osmosis, electrocoagulation, nanofiltration, adsorption, ion-exchange and precipitation/coagulation were introduced in this study. Although several studies have been carried out on contamination of water resources with fluoride, the situation of water contamination with fluoride and newly developed technology to remove fluoride from water in Asian countries has not been reviewed. Therefore, this review is focused on these issues: 1) The status of fluoride contamination in Asian countries, 2) health effects of fluoride contamination in drinking water in Asia, and 3) the existing current technologies for defluoridation in Asia.
Due to their widespread occurrence and detrimental effects on human health and the environment, endocrine-disrupting hazardous chemicals (EDHCs) have become a significant concern. Therefore, numerous physicochemical and biological remediation techniques have been developed to eliminate EDHCs from various environmental matrices. This review paper aims to provide a comprehensive overview of the state-of-the-art remediation techniques for eliminating EDHCs. The physicochemical methods include adsorption, membrane filtration, photocatalysis, and advanced oxidation processes. The biological methods include biodegradation, phytoremediation, and microbial fuel cells. Each technique's effectiveness, advantages, limitations, and factors affecting their performance are discussed. The review also highlights recent developments and future perspectives in EDHCs remediation. This review provides valuable insights into selecting and optimizing remediation techniques for EDHCs in different environmental matrices.
An emerging contaminant of concern in aqueous streams is naproxen. Due to its poor solubility, non-biodegradability, and pharmaceutically active nature, the separation is challenging. Conventional solvents employed for naproxen are toxic and harmful. Ionic liquids (ILs) have attracted great attention as greener solubilizing and separating agent for various pharmaceuticals. ILs have found extensive usage as solvents in nanotechnological processes involving enzymatic reactions and whole cells. The employment of ILs can enhance the effectiveness and productivity of such bioprocesses. To avoid cumbersome experimental screening, in this study, conductor like screening model for real solvents (COSMO-RS) was used to screen ILs. Thirty anions and eight cations from various families were chosen. Activity coefficient at infinite dilution, capacity, selectivity, performance index, molecular interactions using σ-profiles and interaction energies were used to make predictions about solubility. According to the findings, quaternary ammonium cations, highly electronegative, and food-grade anions will form excellent ionic liquid combinations for solubilizing naproxen and hence will be better separating agents. This research will contribute easy designing of ionic liquid-based separation technologies for naproxen. In different separation technologies, ionic liquids can be employed as extractants, carriers, adsorbents, and absorbents.
The introduction of bioactive glasses (BGs) precipitated a paradigm shift in the medical industry and opened the path for the development of contemporary regenerative medicine driven by biomaterials. This composition can bond to live bone and can induce osteogenesis by the release of physiologically active ions. 45S5 BG products have been transplanted effectively into millions of patients around the world, primarily to repair bone and dental defects. Over the years, many other BG compositions have been introduced as innovative biomaterials for repairing soft tissue and delivering drugs. When research first started, many of the accomplishments that have been made today were unimaginable. It appears that the true capacity of BGs has not yet been realized. Because of this, research involving BGs is extremely fascinating. However, to be successful, it requires interdisciplinary cooperation between physicians, glass chemists, and bioengineers. The present paper gives a picture of the existing clinical uses of BGs and illustrates key difficulties deserving to be faced in the future. The challenges range from the potential for BGs to be used in a wide variety of applications. We have high hopes that this paper will be of use to both novice researchers, who are just beginning their journey into the world of BGs, as well as seasoned scientists, in that it will promote conversation regarding potential additional investigation and lead to the discovery of innovative medical applications for BGs.
The rapid increase in the global population and its ever-rising standards of living are imposing a huge burden on global resources. Apart from the rising energy needs, the demand for freshwater is correspondingly increasing. A population of around 3.8 billion people will face water scarcity by 2030, as per the reports of the World Water Council. This may be due to global climate change and the deficiency in the treatment of wastewater. Conventional wastewater treatment technologies fail to completely remove several emerging contaminants, especially those containing pharmaceutical compounds. Hence, leading to an increase in the concentration of harmful chemicals in the human food chain and the proliferation of several diseases. MXenes are transition metal carbide/nitride ceramics that primarily structure the leading 2D material group. MXenes act as novel nanomaterials for wastewater treatment due to their high surface area, excellent adsorption properties, and unique physicochemical properties, such as high electrical conductivity and hydrophilicity. MXenes are highly hydrophilic and covered with active functional groups (i.e., hydroxyl, oxygen, fluorine, etc.), which makes them efficient adsorbents for a wide range of species and promising candidates for environmental remediation and water treatment. This work concludes that the scaling up process of MXene-based materials for water treatment is currently of high cost. The up-to-date applications are still limited because MXenes are currently produced mainly in the laboratory with limited yield. It is recommended to direct research efforts towards lower synthesis cost procedures coupled with the use of more environmentally friendly materials to avoid secondary contamination.
Strict environmental concerns, depleting natural recourses, and rising demand for building construction materials have promoted scientific research toward alternative building materials. This research supports the idea of sustainability and a circular economy via the utilization of waste to produce value-added products. The research explored the potential of waste plastics and silica sand for developing thermoplastic composite as floor tiles. The samples were characterized by water absorption, compressive strength, flexural strength, and sliding wear. The morphological analysis of the sand-plastic interfaces was covered under the umbrella of this study. The maximum compressive and flexural strength were found to be 46.20 N/mm2 and 6.24 N/mm2, respectively, with the minimum water absorption and sliding wear rate of 0.039% and 0.143 × 10-8 kg/m, respectively. The study suggests the workability of the developed floor tiles in non-traffic areas of public places. Thus, the study provides a green building material through recycling waste plastics for sustainable development.
The diverse nature of polymers with attractive properties has replaced the conventional materials with polymeric composites. The present study was sought to evaluate the wear performance of thermoplastic-based composites under the conditions of different loads and sliding speeds. In the present study, nine different composites were developed by using low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polyethylene terephthalate (PET) with partial sand replacements i.e., 0, 30, 40, and 50 wt%. The abrasive wear was evaluated as per the ASTM G65 standard test for abrasive wear through a dry-sand rubber wheel apparatus under the applied loads of 34.335, 56.898, 68.719, 79.461 and 90.742 (N) and sliding speeds of 0.5388, 0.7184, 0.8980, 1.0776 and 1.4369 (m/s). The optimum density and compressive strength were obtained to be 2.0555 g/cm3 and 46.20 N/mm2, respectively for the composites HDPE60 and HDPE50 respectively. The minimum value of abrasive wear were found to 0.02498, 0.03430, 0.03095, 0.09020 and 0.03267 (cm3) under the considered loads of 34.335, 56.898, 68.719, 79.461 and 90.742 (N), respectively. Moreover, the composites LDPE50, LDPE100, LDPE100, LDPE50PET20 and LDPE60 showed a minimum abrasive wear of 0.03267, 0.05949, 0.05949, 0.03095 and 0.10292 at the sliding speeds of 0.5388, 0.7184, 0.8980, 1.0776 and 1.4369 (m/s), respectively. The wear response varied non-linearly with the conditions of loads and sliding speeds. Micro-cutting, plastic deformations, fiber peelings, etc. were included as the possible wear mechanism. The possible correlations between wear and mechanical properties, and throughout discussions for wear behaviors through the morphological analyses of the worn-out surfaces were provided.
Semiconductor metal oxide with TiO2 nanoparticles removes hazardous compounds from environmental samples. TiO2 nanoparticles have shown potential as an efficient photocatalyst by being employed as a nano-catalyst for the breakdown of organic contaminants in wastewater samples. To separate substances from contaminated samples, combined UV and visible light irradiation has been used. Sol-gel synthesis was used to produce a copper chromite-titanium nanocomposite, which was then evaluated using analytical methods, such as XRD, BET, DRS-UV, and FT-IR. Using visible light, the photocatalytic activity of a nanocomposite made of CuCr2O4 and TiO2 was investigated for its role in the breakdown of malachite green. The effects of several parameters, including pH change, anions presence, contact time, catalyst amount, concentration variation, and the kinetics of photocatalytic degradation were investigated. The magnitude of transition energy calculated using UV-DRS spectra was found to be 3.1 eV for CuCr2O4-TiO2 nanocomposite. Maximum degradation was observed at pH 7.0. The surface area and pore volume of the co-doped samples of Cr2O4 - TiO2 obtained from BET were found to be 6.1213 m2/g and 0.045063 cm3/g respectively. The average particle size of the catalyst of the nano-catalysts calculated from XRD was found to be 8 nm for TiO2 and 66 nm for TiO2-CuCrO4. The peaks obtained in FTIR between the range of 900-500 cm-1 were due to the presence of an aromatic compound. The binding mechanism of a dye molecule to the surface of CuCr2O4-TiO2 nanocomposite was analysed using quantum chemical calculations with the self-consistent reaction field technique employing integral equation formalism for the polarized continuum method and the UFF atomic radii set.
The present study describes the phytoremediation performance of water lettuce (Pistia stratiotes L.) for physicochemical pollutants elimination from paper mill effluent (PME). For this, pot (glass aquarium) experiments were conducted using 0% (BWW: borewell water), 25%, 50%, 75%, and 100% treatments of PME under natural day/light regime. Results of the experiments showed that the highest removal of pH (10.75%), electrical conductivity (EC: 63.82%), total dissolved solids (TDS: 71.20%) biological oxygen demand (BOD: 85.03%), chemical oxygen demand (COD: 80.46%), total Kjeldahl's nitrogen (TKN: 93.03%), phosphorus (P: 85.56%), sodium (Na: 91.89%), potassium (K: 84.04%), calcium (Ca: 84.75%), and magnesium (Mg: 83.62%), most probable number (MPN: 77.63%), and standard plate count (SPC: 74.43%) was noted in 75% treatment of PME after treatment by P. stratiotes. PCA showed the best vector length for TKN, Na, and Ca. The maximum plant growth parameters including, total fresh biomass (81.30 ± 0.28 g), chlorophyll content (3.67 ± 0.05 mg g-1 f.wt), and relative growth rate (0.0051 gg-1 d-1 ) was also measured in 75% PME treatment after phytoremediation experiments. The findings of this study make useful insight into the biological management of PME through plant-based pollutant eradication while leftover biomass may be used as a feedstock for low-cost bioenergy production. PRACTITIONER POINTS: Biological treatment of paper mill effluent using water lettuce is presented. Best reduction of physicochemical and microbiological pollutants was attained in 75% treatment. Maximum production of chlorophyll, plant biomass, and highest growth rate was also observed in 75% treatment.
The aim of this study was ultrasound assisted removal of Ceftriaxone sodium (CS) based on CCD model. Using sonochemical synthesized Bi2WO6 implanted on graphitic carbon nitride/Multiwall carbon nanotube (g-C3N4/MWCNT/Bi2WO6). For this purpose g-C3N4/MWCNT/Bi2WO6 was synthesized and characterized using diverse approaches including XRD, FE-SEM, XPS, EDS, HRTEM, FT-IR. Then, the contribution of conventional variables including pH, CS concentration, adsorbent dosage and ultrasound contact time were studied by central composite design (CCD) under response surface methodology (RSM). ANOVA was employed to the variable factors, and the most desirable operational conditions mass provided. Drug adsorption yield of 98.85% obtained under these defined conditions. Through conducting five experiments, the proper prediction of the optimum point were examined. The respective results showed that RSD% was lower than 5% while the t-test confirmed the high quality of fitting. Langmuir isotherm equation fits the experimental data best and the removal followed pseudo-second order kinetics. The estimation of the experimentally obtained maximum adsorption capacities was 19.57 mg.g- of g-C3N4/MWCNT/Bi2WO6 for CS. Boundary layer diffusion explained the mechanism of removal via intraparticle diffusion.
Agriculture is a leading sector in international initiatives to mitigate climate change and promote sustainability. This article exhaustively examines the removals and emissions of greenhouse gases (GHGs) in the agriculture industry. It also investigates an extensive range of GHG sources, including rice cultivation, enteric fermentation in livestock, and synthetic fertilisers and manure management. This research reveals the complex array of obstacles that are faced in the pursuit of reducing emissions and also investigates novel approaches to tackling them. This encompasses the implementation of monitoring systems powered by artificial intelligence, which have the capacity to fundamentally transform initiatives aimed at reducing emissions. Carbon capture technologies, another area investigated in this study, exhibit potential in further reducing GHGs. Sophisticated technologies, such as precision agriculture and the integration of renewable energy sources, can concurrently mitigate emissions and augment agricultural output. Conservation agriculture and agroforestry, among other sustainable agricultural practices, have the potential to facilitate emission reduction and enhance environmental stewardship. The paper emphasises the significance of financial incentives and policy frameworks that are conducive to the adoption of sustainable technologies and practices. This exhaustive evaluation provides a strategic plan for the agriculture industry to become more environmentally conscious and sustainable. Agriculture can significantly contribute to climate change mitigation and the promotion of a sustainable future by adopting a comprehensive approach that incorporates policy changes, technological advancements, and technological innovations.
In this study, water hyacinth (Eichhornia crassipes) was used to treat domestic wastewater. Ten organic and inorganic parameters were monitored in three weeks for water purification. The six chemical, biological and physical parameters included Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Ammoniacal Nitrogen (NH3-N), Total Suspended Solids (TSS), and pH were compared with the Interim National Water Quality Standards, Malaysia River classification (INWQS) and Water Quality Index (WQI). Between 38% to 96% of reduction was observed and water quality has been improved from class III and IV to class II. Analyses for Electricity Conductivity (EC), Salinity, Total Dissolved Solids (TDS) and Ammonium (NH4) were also investigated. In all parameters, removal efficiency was in range of 13-17th day (optimum 14th day) which was higher than 3 weeks except DO. It reveals the optimum growth rate of water hyacinth has great effect on waste water purification efficiency in continuous system and nutrient removal was successfully achieved.
Environmental pollution specifically water pollution is alarming both in the developed and developing countries. Heavy metal contamination of water resources is a critical issue which adversely affects humans, plants and animals. Phytoremediation is a cost-effective remediation technology which able to treat heavy metal polluted sites. This environmental friendly method has been successfully implemented in constructed wetland (CWs) which is able to restore the aquatic biosystem naturally. Nowadays, many aquatic plant species are being investigated to determine their potential and effectiveness for phytoremediation application, especially high growth rate plants i.e. macrophytes. Based on the findings, phytofiltration (rhizofiltration) is the sole method which defined as heavy metals removal from water by aquatic plants. Due to specific morphology and higher growth rate, free-floating plants were more efficient to uptake heavy metals in comparison with submerged and emergent plants. In this review, the potential of wide range of aquatic plant species with main focus on four well known species (hyper-accumulators): Pistia stratiotes, Eicchornia spp., Lemna spp. and Salvinia spp. was investigated. Moreover, we discussed about the history, methods and future prospects in phytoremediation of heavy metals by aquatic plants comprehensively.
Microplastics (MPs) are generated from plastic and have negative impact to our environment due to high level of fragmentation. They can be originated from various sources in different forms such as fragment, fiber, foam and so on. For detection of MPs, many techniques have been developed with different functions such as microscopic observation, density separation, Raman and FTIR analysis. Besides, due to ingestion of MPs by wide range of marine species, research on the effect of this pollution on biota as well as human is vital. Therefore, we comprehensively reviewed the occurrence and distribution of MPs pollution in both marine and freshwater environments, including rivers, lakes and wastewater treatment plants (WWTPs). For future studies, we propose the development of new techniques for sampling MPs in aquatic environments and biota and recommend more research regarding MPs release by WWTPs.
In this study, palm oil mill effluent (POME) was treated using electrocoagulation, whereby the influencing factors including voltage, electrolysis time, and electrolyte amount were optimized to achieve the highest chemical oxygen demand (COD) and color removal efficiencies. Graphite was selected as electrode material due to its performance better compared to aluminum and copper. Response surface methodology (RSM) was carried out for optimization of the electrocoagulation operating parameters. The best model obtained using Box-Behnken design (BBD) were quadratic for COD removal (R2 = 0.9844), color reduction (R2 = 0.9412), and oil and grease removal (R2 = 0.9724). The result from the analysis of variance (ANOVA) was obtained to determine the relationship between factors and treatment efficiencies. The experimental results under optimized conditions such as voltage 14, electrolysis time of 3 h, and electrolyte amount of 13.41 g/L show that the electrocoagulation process effectively reduced the COD (56%), color (65%), and oil and grease (99%) of the POME treatment. Graphical abstract.
Hydrogen (H2) is a possible energy transporter and feedstock for energy decarbonization, transportation, and chemical sectors while reducing global warming's consequences. The predominant commercial method for producing H2 today is steam methane reforming (SMR). However, there is still room for development in process intensification, energy optimization, and environmental concerns related to CO2 emissions. Reactors using metallic membranes (MRs) can handle both problems. Compared to traditional reactors, MRs operates at substantially lower pressures and temperatures. As a result, capital and operational costs may be significantly cheaper than traditional reactors. Furthermore, metallic membranes (MMs), particularly Pd and its alloys, naturally permit only H2 permeability, enabling the production of a stream with a purity of up to 99.999%. This review describes several methods for H2 production based on the energy sources utilized. SRM with CO2 capture and storage (CCUS), pyrolysis of methane, and water electrolysis are all investigated as process technologies. A debate based on a color code was also created to classify the purity of H2 generation. Although producing H2 using fossil fuels is presently the least expensive method, green H2 generation has the potential to become an affordable alternative in the future. From 2030 onward, green H2 is anticipated to be less costly than blue hydrogen. Green H2 is more expensive than fossil-based H2 since it uses more energy. Blue H2 has several tempting qualities, but the CCUS technology is pricey, and blue H2 contains carbon. At this time, almost 80-95% of CO2 can be stored and captured by the CCUS technology. Nanomaterials are becoming more significant in solving problems with H2 generation and storage. Sustainable nanoparticles, such as photocatalysts and bio-derived particles, have been emphasized for H2 synthesis. New directions in H2 synthesis and nanomaterials for H2 storage have also been discussed. Further, an overview of the H2 value chain is provided at the end, emphasizing the financial implications and outlook for 2050, i.e., carbon-free H2 and zero-emission H2.
Microplastics (MPs) in environmental studies have revealed that public sewage treatment plants are a common pathway for microplastics to reach local surroundings. Microplastics are becoming more of a worry, posing a danger to both marine wildlife and humans. These plastic items not only contribute to the macrocosmic proliferation of plastics but also the scattering of microplastics and the concentration of other micropollutant-containing objects, increasing the number of pollutants identified. Microplastics' behavior, movement, transformation, and persistence mechanisms, as well as their mode of action in various wastewater effluent treatment procedures, are still unknown. They are making microplastics made from wastewater a big deal. We know that microplastics enter wastewater treatment facilities (WWTPs), that wastewater is released into the atmosphere, and that this wastewater has been considered to represent a threat to habitats and ground character based on our literature assessment. The basic methods of wastewater and sewage sludge, as well as the treatment procedure and early characterization, are covered throughout the dissection of the problematic scientific conceptualization.