Methods to prepare biosorbents and magnetic sorbents for water treatment: a review

Access to drinkable water is becoming more and more challenging due to worldwide pollution and the cost of water treatments. Water and wastewater treatment by adsorption on solid materials is usually cheap and effective in removing contaminants, yet classical adsorbents are not sustainable because they are derived from fossil fuels, and they can induce secondary pollution. Therefore, biological sorbents made of modern biomass are increasingly studied as promising alternatives. Indeed, such biosorbents utilize biological waste that would otherwise pollute water systems, and they promote the circular economy. Here we review biosorbents, magnetic sorbents, and other cost-effective sorbents with emphasis on preparation methods, adsorbents types, adsorption mechanisms, and regeneration of spent adsorbents. Biosorbents are prepared from a wide range of materials, including wood, bacteria, algae, herbaceous materials, agricultural waste, and animal waste. Commonly removed contaminants comprise dyes, heavy metals, radionuclides, pharmaceuticals, and personal care products. Preparation methods include coprecipitation, thermal decomposition, microwave irradiation, chemical reduction, micro-emulsion, and arc discharge. Adsorbents can be classified into activated carbon, biochar, lignocellulosic waste, clays, zeolites, peat, and humic soils. We detail adsorption isotherms and kinetics. Regeneration methods comprise thermal and chemical regeneration and supercritical fluid desorption. We also discuss exhausted adsorbent management and disposal. We found that agro-waste biosorbents can remove up to 68–100% of dyes, while wooden, herbaceous, bacterial, and marine-based biosorbents can remove up to 55–99% of heavy metals. Animal waste-based biosorbents can remove 1–99% of heavy metals. The average removal efficiency of modified biosorbents is around 90–95%, but some treatments, such as cross-linked beads, may negatively affect their efficiency.

     

Ozonation of metoprolol in aqueous solution: ozonation by-products and mechanisms of degradation

This study investigated the degradation pathway of metoprolol, a widely used β-blocker, in the ozonation via the identification of generated ozonation by-products (OPs). Structure elucidation of OPs was performed using HPLC coupled with quadrupole time-of-flight high-resolution mass spectrometry. Seven OPs were identified, and four of these have not been reported elsewhere. Identified OPs of metoprolol included aromatic ring breakdown by-products; aliphatic chain degraded by-products and aromatic ring mono-, di-, and tetrahydroxylated derivatives. Based on the detected OPs, metoprolol could be degraded through aromatic ring opening reaction via reaction with ozone (O₃) and degradation of aliphatic chain and aromatic ring via reaction with hydroxyl radical (?OH).     

Biofuel production,hydrogen production and water remediation by photocatalysis,biocatalysis and electrocatalysis

The energy crisis and environmental pollution have recently fostered research on efficient methods such as environmental catalysis to produce biofuel and to clean water. Environmental catalysis refers to green catalysts used to breakdown pollutants or produce chemicals without generating undesirable by-products. For example, catalysts derived from waste or inexpensive materials are promising for the circular economy. Here we review environmental photocatalysis, biocatalysis, and electrocatalysis, with focus on catalyst synthesis, structure, and applications. Common catalysts include biomass-derived materials, metal–organic frameworks, non-noble metals nanoparticles, nanocomposites and enzymes. Structure characterization is done by Brunauer–Emmett–Teller isotherm, thermogravimetry, X-ray diffraction and photoelectron spectroscopy. We found that water pollutants can be degraded with an efficiency ranging from 71.7 to 100%, notably by heterogeneous Fenton catalysis. Photocatalysis produced dihydrogen (H₂) with generation rate higher than 100 μmol h⁻¹. Dihydrogen yields ranged from 27 to 88% by methane cracking. Biodiesel production reached 48.6 to 99%.

     

Biosafety Act 2007: Does It Really Protect Bioethical Issues Relating To GMOS

Despite the (serious) global concerns about the safety and genetic stability of genetically modified organisms, the Malaysian National Biosafety Board (NBB) has recently approved the field testing for genetically modified (GM) male mosquitoes. With this development, bioethical issues, which in some respect could adversely impinge on the social, economic and environmental aspects of the society, have surfaced, and these concerns must be addressed by the authorities concerned. In reviewing this application, the National Biosafety Board has followed the requirements of the Biosafety Act 2007, which was created to strike a balance between promoting biotechnology and at the same time protecting against its potential environmental and human health risks in Malaysia. However, the 2007 Act fails to adequately take into account any bioethical issues in spite of the inclusion of a provision on socio-economic consideration. As part of an ongoing doctoral research project, and by way of an instrumental critique of the 2007 Act, the present paper attempts to address the role and function of the Malaysia biosafety legal framework in governing bioethical concerns relating to Genetically Modified Organisms (GMOs) within the current biotechnology background in Malaysia. Additionally, the paper suggests that the ambiguity of the provisions contained within the 2007 Act in governing such concerns, representing wider societal interests and welfare, in some ways might defeat the balancing role that this act was originally intended to fulfil.     

Occupational exposure to gasoline in gasoline station male attendants promotes M1 polarization in macrophages

Environmental Science and Pollution Research - Several studies have reported the toxicological implications of exposure to petroleum hydrocarbon fumes in animal models. There is little...     

Performance improvement and advancement studies of mixed-mode solar thermal dryers: a review

Solar thermal dryers are solar-operated gadgets utilized to dehumidify various products, especially food items and rubber sheets. This article provides detailed design, parametric studies, and an in-depth review of mixed-mode solar dryers (MMSD) with a case study of fish drying near coastal lines. Due to several advantages compared to open sun drying and prominent performance index compared to indirect and direct type solar dryers, mixed-mode solar dryers have large adaptability on the field. Moreover, mixed-mode solar thermal dryers with different augmentations are reviewed, for instance, mixed-mode solar dryers with evacuated tube collectors, phase change materials, ultraviolet rays stabilized housing, and dehumidifiers. The case study of fish drying near the coastal line of Gujarat, India has been carried out to study the present scenario of the drying activities. Hence, the objective of this review is to identify the capable mixed-mode solar dryer with heat recovery systems. Substantial reviews within the article suggest an essential need to implement the hybrid mixed-mode solar dryer cum distiller technology for small-scale enterprises that can simultaneously provide potable water near coastal lines along with drying of fishes from the solar dryer. Furthermore, future research demands such hybrid mixed-mode solar drying systems that strongly fulfill the requirements of local communities near coastal lines involved in fish drying activities.

     

The impact of storm events on a riverbed system and its hydraulic conductivity at a site of induced infiltration

The spatial and temporal variability of riverbed vertical hydraulic conductivity (K(v)) was investigated at a site of induced infiltration, associated with a municipal well field, to assess the impact of high-stage events on scour and subsequently the riverbed K(v). Such impacts are important when considering the potential loss of riverbank filtration capacity due to storm events. The study site, in and along the Great Miami River in southwest Ohio, overlaid a highly productive glacial-outwash aquifer. A three-layer model for this system was conceptualized: a top layer of transient sediment, a second layer comprising large sediment resistant to scour, but clogged with finer sediment (the armor/colmation layer), and a third layer that was transitional to the underlying higher-K(v) aquifer. One location was studied in detail to confirm and quantify the conceptual model. Methods included seepage meters, heat-flow modeling, grain-size analyses, laboratory permeameter tests, slug tests and the use of scour chains and pressure-load cells to directly measure the amount of sediment scour and re-deposition. Seepage meter measured riverbed K(v) ranged from 0.017 to 1.7 m/d with a geometric mean of 0.19 m/d. Heat-transport model-calibrated estimates were even lower, ranging from 0.0061 to 0.046 m/d with a mean of 0.017 m/d. The relatively low K(v) was indicative of the clogged armor layer. In contrast, slug tests in the underlying riverbed sediment yielded K(v) values an order of magnitude greater. There was a linear relationship between scour chain measured scour and event intensity with a maximum scour of only 0.098 m. Load-cell pressure sensor data over a 7-month period indicated a total sediment-height fluctuation of 0.42 m and a maximum storm-event scour of 0.28 m. Scour data indicated that the assumed armor/colmation layer almost always remained intact. Based on measured layer conductivities and thicknesses, the overall K(v) of this conceptualized system was 1.6 m/d. Sensitivity analyses indicated that even complete scour of the armor/colmation layer would likely increase the overall K(v) only by a factor of 1.5. Most scour events observed removed only the transient sediment, having very little effect on the entire system indicating low risk of losing filtration capacity during storms. The research, however, focused on the point bar, depositional side of the river. More research of the entire river profile is necessary.     

An experimental investigation of a water desalination unit using different microparticle-coated absorber plate: yield,thermal, economic,and environmental assessments

Environmental Science and Pollution Research - This study aims to augment the performance of a solar desalination unit. To experimental examine this idea, a modified solar still with three...     

Deciphering epigenetic(s) role in modulating susceptibility to and severity of COVID-19 infection and/or outcome: a systematic rapid review

Environmental Science and Pollution Research - COVID-19 pandemic waves hitting worldwide result in drastic postinfection complications with interindividual variations, which raised the question for...