Efficient cesium encapsulation from contaminated water by cellulosic biomass based activated wood charcoal

Zearalenone removal using inactivated yeast embedded in porous modified yam starch aerogels and its application in corn silk tea

Zearalenone contaminates food and poses a threat to human health. It is vital to develop cost-effective and environmentally-friendly adsorbents for its removal. By screening Sporobolomyces pararoseus (SZ4) and modified yam starch (adsorption capacity (qe) of 1.33 and 0.94 mg/g, respectively), this study prepared a novel composite aerogel adsorbent (P-YSA@SZ410). The compressive strength of P-YSA@SZ410 was 1.35-fold higher than unloaded yeast. It contained several functional groups and three-dimensional interconnected channels, achieving a 0° contact angle within 0.18 s, thereby demonstrating excellent water-absorbent properties. With a qe of 2.96 mg/g at 308 K, the adsorption process of P-YSA@SZ410 was spontaneous, endothermic, and matched pseudo-second-order and Langmuir models. The composite adsorbed zearalenone via electrostatic attraction and hydrogen bonding, maintaining a qe of 2.24 mg/g after five cycles. P-YSA@SZ410 was found to remove zearalenone effectively under various conditions and could be applied to corn silk tea, indicating its great potential as an adsorbent material.

Cesium adsorption from an aqueous medium for environmental remediation: A comprehensive analysis of adsorbents, sources, factors, models, challenges, and opportunities

Considering the widespread and indispensable nature of nuclear energy for future power generation, there is a concurrent increase in the discharge of radioactive Cs into water streams. Recent studies have demonstrated that adsorption is crucial in removing Cs from wastewater for environmental remediation. However, the existing literature lacks comprehensive studies on various adsorption methods, the capacities or efficiencies of adsorbents, influencing factors, isotherm and kinetic models of the Cs adsorption process. A bibliometric and comprehensive analysis was conducted using 1179 publications from the Web of Science Core Collection spanning from 2014 to 2023. It reviews and summarizes current publication trends, active countries, adsorption methods, adsorption capacities or efficiencies of adsorbents, tested water sources, influencing factors, isotherm, and kinetic models of Cs adsorption. The selection of suitable adsorbents and operating parameters is identified as a crucial factor. Over the past decade, due to their notable capacity for Cs adsorption, considerable research has focused on novel adsorbents, such as Prussian blue, graphene oxide, hydrogel, and nanoadsorbents (NA). However, there remains a need for further development of application-oriented laboratory-scale experiments. Future research directions should encompass exploring adsorption mechanisms, developing new adsorbents or their combinations, practical applications of lab-scale studies, and recycling radioactive Cs from wastewater. Drawing upon this literature review, we present the most recent research patterns concerning adsorbents to remove Cs, outline potential avenues for future research, and delineate the obstacles hindering effective adsorption. This comprehensive bibliometric review provides valuable insights into prevalent research focal points and emerging trends, serving as a helpful resource for researchers and policymakers seeking to understand the dynamics of adsorbents for Cs removal from water.

Linear and nonlinear regression modelling of industrial dye adsorption using nanocellulose@chitosan nanocomposite beads

Nanocellulose@chitosan (nc@ch) composite beads were prepared via coagulation technique for the elimination of malachite green dye from aqueous solution. As malachite green dye is highly used in textile industries for dyeing purpose which after usage shows fatal effects to the ecosystems and human beings also. In this study the formulated nanocellulose@chitosan composite beads were characterized by Particle size analysis (PSA), Field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis were done to evaluate nanoparticles size distribution, morphological behaviour, functional group entities and degree of crystallinity of prepared beads. The nanocomposite beads adsorption performance was investigated for malachite green (MG) dye and BET analysis were also recorded to know about porous behaviour of the nanocomposite beads. Maximum removal of malachite green (MG) dye was found to be 72.0 mg/g for 100 ppm initial dye concentration. For accurate observations linear and non-linear modelling was done to know about the best-fitted adsorption model during the removal mechanism of dye molecules, on evaluating it has been observed that Langmuir isotherm and Freundlich isotherm show best-fitted observation in the case of linear and non-linear isotherm respectively (R2 = 0.96 & R2 = 0.957). In the case of kinetic linear models, the data was well fitted with pseudo-second-order showing chemosorption mechanism (R2 = 0.999), and in the case of non-linear kinetic model pseudo first order showed good fit showing physisorption mechanism during adsorption (R2 = 0.999). The thermodynamic study showed positive values for ΔH° and ΔS° throughout the adsorption process respectively, implying an endothermic behaviour. In view of cost effectiveness, desorption or regeneration study was done and it was showed that after the 5th cycle, the removal tendency had decreased from 48 to 38 % for 20-100 ppm dye solution accordingly. Thus, nanocomposite beads prepared by the coagulation method seem to be a suitable candidate for dye removal from synthetic wastewater and may have potential to be used in small scale textile industries for real wastewater treatment.

Inclusive study of peanut shells derived activated carbon as an adsorbent for removal of lead and methylene blue from water

Green and efficient agro-waste-based activated carbon has been prepared utilizing peanut shells for adsorptive elimination of an industrial dye, methylene blue, and lead from polluted water. The carbonaceous biomass obtained from peanut shells was chemically activated using either NaOH, ZnCl2, or steam and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and N2 adsorption and desorption studies. The adsorption process was optimal for methylene blue at alkaline pH, while pH 4.5 was optimal for Pb (II) adsorption. The adsorption takes place through pseudo-second-order kinetic, and the rate-governing step of the adsorption procedure are intraparticle diffusion and film diffusion. Furthermore, the thermodynamics of the adsorption process has been studied, and the obtained Gibbs free energy (ΔG°) values are negative (- 35.90 to - 43.59 kJ mol-1) indicating the spontaneous adsorption of the investigated pollutants on the prepared activated carbon. As per the correlation coefficient, the obtained results were best fit by the Langmuir isotherm with maximum adsorption capacity of 303.03 mg g-1 for methylene blue and 130.89 mg g-1 for Pb (II). The activated carbon successfully removed methylene blue and Pb (II) with %removal exceeding 95%. The mechanisms of interaction of Pb (II) with the activated carbon is a combination of electrostatic interaction and ion exchange, while methylene blue interacts with the activated carbon via π-π interaction, hydrogen bonds, and electrostatic interaction. Thus, the prepared activated carbon has been employed to decontaminate wastewater and groundwater samples. The developed agro-waste-based activated carbon is a promising, cost-efficient, green, and accessible tool for water remediation.

Magnetic hierarchical titanium ferrocyanide for the highly efficient and selective removal of radioactive cesium from water

Selective adsorption is the most suitable technique for eliminating trace amounts of 137Cs from various volumes of 137Cs-contaminated water, including seawater. Although various metal ferrocyanide (MFC)-functionalized magnetic adsorbents have been developed for the selective removal of 137Cs and magnetic recovery of adsorbents, their adsorption capacity for Cs remains low. Here, magnetic hierarchical titanium ferrocyanide (mh-TiFC) was synthesized for the first time for enhanced Cs adsorption. Hierarchical TiFC, comprising 2-dimensional TiFC flakes, was synthesized on SiO2-coated magnetic Fe3O4 particles using a sacrificial TiO2 shell as a source of Ti4+ via a reaction with ferrocyanide under acidic conditions. The resultant mh-TiFC exhibited the highest maximum adsorption capacity (434.8 mg g-1) and enhanced Cs selectivity with an excellent Kd value (6,850,000 mL g-1) compared to those of previously reported magnetic Cs adsorbents. This enhancement was attributed to the hierarchical structure, which reduced intracrystalline diffusion and increased the surface area available for direct Cs adsorption. Additionally, mh-TiFC (0.1 g L-1) demonstrated an excellent removal efficiency of 137Cs exceeding 99.85% for groundwater and seawater containing approximately 22 ppt 137Cs. Therefore, mh-TiFC offers promising applications for the treatment of 137Cs-contaminated water.

The mechanism and behavior of cesium adsorption from aqueous solutions onto carbonated cement slurry powder

In this study, microstructural differences and changes in the adsorption capacity of cesium between cement and carbonated cement were investigated. Cement blocks were ground to powder for rapid carbonation, and microscopic variations were characterized by XRF, XRD, FT-IR, SEM, BET, and TGA. The characterization results show that the conversion of Ca(OH)2 and calcium silicate hydrate (C-S-H) gel to CaCO3 in cement after carbonation. And the component of Ca(OH)2 in the powder sample disappeared after three days of rapid carbonation. Batch experiments were used to investigate adsorption under the influence of time, initial cesium concentration, temperature, and ion coexistence. Pseudo-second-order kinetic and Langmuir isothermal model fitting could better describe the adsorption process and the results show that the maximum adsorption capacity of cement after carbonation surges from 29.6 μg‧g-1 to 1.58-5.89 mg‧g-1. (Different carbonating times lead to varying adsorption capacity.) The adsorption capacity decreases with increasing temperature. At temperatures of 293 K and 333 K, the calculated Gibbs free energy change values of cement with different carbonated degrees adsorbing cesium are -10.3 ∼ -14.9 kJ‧mol-1 and -8.03 ∼ -12.4 kJ‧mol-1. And the calculated values of enthalpy change and entropy change are -18.8 ∼ -23.8 kJ‧mol-1 and -27.9 ∼ -37.1 J‧mol-1‧K-1. Combining the characterization and adsorption results, the huge increase in cesium adsorption capacity is closely related to the conversion of Ca(OH)2 to CaCO3, which will provide a new perspective on the adsorption mechanism of cesium in cement.

Intimate coupling of gC3N4/CdS semiconductor on eco-friendly biocarrier loofah sponge for enhanced detoxification of ciprofloxacin

Ciprofloxacin is one of the antibiotics predominantly used to treat bacterial infections, however excess usage, and release of antibiotic from various sources to the environment can cause severe risks to human health since it was considered as emerging pollutant. This study deals with the intimately coupled photocatalysis and biodegradation (ICPB) of ciprofloxacin using gC3N4/CdS photocatalytic semiconductor and eco-friendly renewable loofah sponge as biocarrier in the ICPB. The photocatalyst gC3N4/CdS was prepared and their synergistic photocatalytic degradation of ciprofloxacin were assessed and the results shows that gC3N4/CdS (20%) exhibit 79% degradation efficiency in 36 h. Further ICPB exhibited enhanced ciprofloxacin degradation 95% at 36 h. The 62.4% and 81.1% of chemical oxygen demand (COD) removal was obtained in the photocatalysis and ICPB respectively. Enhanced degradation of ciprofloxacin and COD removal was due to the synergetic photoelectrons generated from the gC3N4/CdS (20%) transferred to the bacterial communities which intensely mineralize the degradation products produced from the photocatalysis process. Furthermore, production of hydroxyl •OH and superoxide radical anion O2• were identified actively involved in the degradation of ciprofloxacin. The biocarrier loofah sponge provided favourable environment to the bacterial communities for the formation of biofilm and production of extracellular polymeric substances (EPS). Excess quantity of EPS production in the ICPB helps in the prevention of toxicity of photocatalyst to bacterial communities as well as facilitate the extracellular electron transfer process. This work provides a novel path for enhanced degradation of ciprofloxacin using eco-friendly, low cost and renewable biocarrier loofah sponge in the ICPB system.

Development of a green metallochromic indicator for selective and visual detection of copper(II) ions

Heavy metal ions, i.e., copper(II) (Cu(II)), are harmful to the environment and our health. The current research established an eco-friendly and efficient metal-sensitive indicator, which can identify Cu(II) ions in both liquid and solid forms, by utilizing anthocyanin extract obtained from jambolao fruit (Syzgium cumini) that is incorporated within bacterial cellulose nanofibers (BCNF).The CIE Lab color parameters demonstrated that Cu(II) binding causes a sensible change in color. It was observed that the visible color altered with an increase in the Cu(II) concentration. The bacterial cellulose nanofibers that were altered with anthocyanin were analyzed using ATR-FTIR and FESEM. The sensor's selectivity was tested by using a range of metal ions such as lead (Pb2+), cobalt (Co2+), cadmium (Cd2+), nickel (Ni2+), aluminium (Al3+), barium (Ba2+), manganese (Mn2+), zinc (Zn2+), mercury (Hg2+) and sodium (Na+). The findings demonstrated that the suggested sensor showed excellent selectivity toward Cu(II) ion. Cu(II) can be accurately identified using the sensing technique, with detection limits ranging from 10-400 ppm and 50-500 ppm for liquid and solid samples, respectively, and through observation with naked eye. The fabricated green metallochromic sensor is promising to be a simple, cheap, mobile and easily operable for the real-time and on-site detection of Cu(II) ion.

Failure Mechanism of the Corrugated Medium under Simulated Cold Chain Logistics

It is necessary to develop corrugated medium food packaging, which is suitable for highly humid environments, to meet the demands of cold chain logistics. In this paper, we investigated the influence of the transverse ring crush index of different environmental factors of corrugated medium and the failure mechanisms during cold chain transportation. After freeze-thaw treatment of corrugated medium, XRD and DP showed a decrease in crystallinity and polymerization of 3.47 and 7.83%, respectively. Also, the FT-IR spectra of the paper showed that the number of intermolecular hydrogen bonds decreased by about 3.00% after freezing. SEM and XRD showed CaCO₃ precipitation on the paper surface and a 26.01% increase in pore size. This study would be beneficial in further expanding the applications of cellulose-based paperboard cold chain transportation.

Simultaneous achievement of efficient hemicellulose separation and inhibition of lignin repolymerization using pyruvic acid treatment

The efficiency of organic acid treatment in the conversion of lignocellulosic biomass fractions has been widely recognized. In this study, a novel green pyruvic acid (PA) treatment is proposed. The higher separation efficiency of eucalyptus hemicellulose was obtained at 4.0% PA and 150 °C. The hemicellulose separation yield was increased from 71.71 to 88.09% compared to glycolic acid (GA) treatment. In addition, the treatment time was significantly reduced from 180 to 40 min. The proportion of cellulose in the solid increased after PA treatment. However, the accompanying separation of lignin was not effectively controlled. Fortunately, a six-membered ring structure was formed on the diol structure of the lignin β-O-4 side chain. Fewer lignin-condensed structures were observed. High-value lignin rich in phenol hydroxyl groups were obtained. It provides a green path for the simultaneous achievement of efficient hemicellulose separation and inhibition of lignin repolymerization using organic acid treatment.

Abscisic acid (ABA) alleviates cadmium toxicity by enhancing the adsorption of cadmium to root cell walls and inducing antioxidant defense system of Cosmos bipinnatus

Cadmium (Cd) pollution is a global problem affecting soil ecology and plant growth. Abscisic acid (ABA) acts as a growth and stress hormone, regulates cell wall synthesis, and plays an important role in plant responses to stress. There are few studies on the mechanisms behind abscisic acid alleviation of cadmium stress in Cosmos bipinnatus, especially in regards to regulation of the root cell wall. This study examined the effects of different concentrations of abscisic acid at different concentrations of cadmium stress. Through adding 5 μmol/L and 30 μmol/L cadmium, followed by spraying 10 μmol/L and 40 μmol/L ABA in a hydroponic experiment, it was found that under two concentrations of cadmium stress, low concentration of ABA improved root cell wall polysaccharide, Cd, and uronic acid content. Especially in pectin, after the application of low concentration ABA, the cadmium concentration was significantly increased by 1.5 times and 1.2 times compared with the Cd concentration under Cd5 and Cd30 treatment alone, respectively. Fourier-Transform Infrared spectroscopy (FTIR) demonstrated that cell wall functional groups such as -OH and -COOH were increased with exposure to ABA. Additionally, the exogenous ABA also increased expression of three kinds of antioxidant enzymes and plant antioxidants. The results of this study suggest that ABA could reduce Cd stress by increasing Cd accumulation, promoting Cd adsorption on the root cell wall, and activating protective mechanisms. This result could help promote application of C. bipinnatus for phytostabilization of cadmium-contaminated soil.

Anthocyanin-induced color changes in bacterial cellulose nanofibers for the accurate and selective detection of Cu(II) in water samples

The environment and our health are negatively impacted by heavy metal ions, like Cu(II). The present study developed a green and effective metallochromic sensor that detects copper (Cu(II)) ions in solution and solid state using anthocyanin extract from black eggplant peels embedded in bacterial cellulose nanofibers (BCNF). Cu(II) is quantitatively detected by the sensing method with detection limits between 10-400 ppm and 20-300 ppm in solution and solid state, respectively. In the solution state, we depicted a sensor for Cu(II) ions in aqueous matrices in the pH range from 3.0 to 11.0, with the capability to produce a visual color change from brown to light blue and dark blue depending on the Cu(II) concentration. Additionally, BCNF-ANT film can act as a sensor for Cu(II) ions in the pH range of 4.0-8.0. Neutral pH was selected from the standpoint of high selectivity. It was found that visible color changed when Cu(II) concentration was increased. Bacterial cellulose nanofibers modified with anthocyanin were characterized with ATR-FTIR and FESEM. Various metal ions, including Pb²⁺, Co²⁺, Zn²⁺, Ni²⁺, Al³⁺, Ba²⁺, Hg²⁺, Mg²⁺, and Na⁺, were used to challenge the sensor to determine its selectivity. Anthocyanin solution and BCNF-ANT sheet were employed in the actual tap water sample successfully. The results also clarified that the various foreign ions did not significantly interfere with Cu(II) ions detection at optimum conditions. Compared to previously developed sensors, no electronic components, trained personnel, or sophisticated equipment were needed to apply the colorimetric sensor developed in this research. Cu(II) contamination in food matrices and water can be monitored on-site easily.

Green synthesize of nano-MOF-ethylcellulose composite fibers for efficient adsorption of Congo red from water

Two novel MOF- ethyl cellulose (EC)- based nanocomposites have been designed and synthesized in water by electrospinning and applied for adsorption of congo red (CR) in water. Nano- Zeolitic Imidazolate Framework-67 (ZIF-67), and Materials of Institute Lavoisier (MIL-88A) were synthesized in aqueous solutions by a green method. To enhance the dye adsorption capacity and stability of MOFs, they have been incorporated into EC nanofiber to prepare composite adsorbents. The performance of both composites in the absorption of CR, a common pollutant in some industrial wastewaters, has then been investigated. Various parameters including initial dye concentration, the dosage of the adsorbent, pH, temperature and contact time were optimized. The results indicated 99.8 and 90.9% adsorption of CR by EC/ZIF-67 and EC/MIL-88A, respectively at pH = 7 and temperature at 25 °C after 50 min. Furthermore, the synthesized composites were separated conveniently and successfully reused five times without significant loss of their adsorption activity. For both composites, the adsorption behavior can be explained by pseudo-second-order kinetics, Intraparticular diffiusion and Elovich models demonstrated that the experimental data well matched to the pseudo-second-order kinetics. Intraparticular diffiusion model showed that the adsorption of CR on EC/ZIF-67 and EC/MIL-88a took place in one and two steps, respectively. Freundlich isotherm models and thermodynamic analysis indicated exothermic and spontaneous adsorption.

Behavior and mechanisms of ciprofloxacin adsorption on aged polylactic acid and polyethlene microplastics

Microplastics (MPs) and antibiotics are emerging pollutants in aquatic environments. MPs can absorb antibiotics, resulting in compound pollution. Batch adsorption experiments were used to investigate the adsorption behavior of CIP on polylactic (PLA) and polyethlene (PE) under various environmental conditions. After a lengthy aging process, both MPs underwent significant physicochemical changes. The equilibrium adsorption capacities of aged PLA and PE were 0.382 mg/g and 0.28 mg/g, respectively, which increased by 18.06% and 75% compared to pristine PLA and PE. The sorption capacity of MPs increased when the pH of the solution approached the dissociation constant (6.09, 8.74) of CIP. When the salinity of the solution was 3.5%, the adsorption capacity of MPs was reduced by more than 65%. The adsorption capacity of MPs rapidly decreased when 20 mg/L fulvic acid was added. Because norfloxacin (NOR) competes for adsorption sites on the microplastic, CIP adsorption is inhibited. Based on the adsorption models, FTIR, and XPS spectra, we demonstrated that the process was monolayer adsorption, with chemical and physical mechanisms including hydrogen bonding, π-π conjugation, ion exchange, and electrostatic interactions controlling it. Thus, PLA and PE microplastics may be a potential vector for CIP in water, and their interaction is mainly influenced by the physicochemical properties of the MPs and environmental factors.

Alkali-oxygen cooking coupled with ultrasonic etching for directly defibrillation of bagasse parenchyma cells into cellulose nanofibrils

A scheme combining alkali‑oxygen cooking and ultrasonic etching cleaning was developed for the short range preparation of CNF from bagasse pith, which has a soft tissue structure and is rich in parenchyma cells. This scheme expands the utilization path of sugar waste sucrose pulp. The effect of NaOH, O₂, macromolecular carbohydrates, and lignin on subsequent ultrasonic etching was analyzed, and it was found that the degree of alkali‑oxygen cooking was positively correlated with the difficulty of subsequent ultrasonic etching. The mechanism of ultrasonic nano-crystallization was found to be the bidirectional etching mode from the edge and surface cracks of the cell fragments by ultrasonic microjet in the microtopography of CNF. The optimum preparation scheme was obtained under the condition of 28 % NaOH content and 0.5 MPa O₂, which solves the problem of low-value utilization of bagasse pith and environmental pollution, providing a new possibility for the source of CNF.

Healthcare waste in Bangladesh: Current status, the impact of Covid-19 and sustainable management with life cycle and circular economy framework

COVID-19 has accelerated the generation of healthcare (medical) waste throughout the world. Developing countries are the most affected by this hazardous and toxic medical waste due to poor management systems. In recent years, Bangladesh has experienced increasing medical waste generation with estimated growth of 3 % per year. The existing healthcare waste management in Bangladesh is far behind the sustainable waste management concept. To achieve an effective waste management structure, Bangladesh has to implement life cycle assessment (LCA) and circular economy (CE) concepts in this area. However, inadequate data and insufficient research in this field are the primary barriers to the establishment of an efficient medical waste management systen in Bangladesh. This study is introduced as a guidebook containing a comprehensive overview of the medical waste generation scenario, management techniques, Covid-19 impact from treatment to testing and vaccination, and the circular economy concept for sustainable waste management in Bangladesh. The estimated generation of medical waste in Bangladesh without considering the surge due to Covid-19 and other unusual medical emergencies would be approximately 50,000 tons (1.25 kg/bed/day) in 2025, out of which 12,435 tons were predicted to be hazardous waste. However, our calculation estimated that a total of 82,553, 168.4, and 2300 tons of medical waste was generated only from handling of Covid patients, test kits, and vaccination from March 2021 to May 2022. Applicability of existing guidelines, and legislation to handle the current situation and feasibility of LCA on medical waste management system to minimize environmental impact were scrutinized. Incineration with energy recovery and microwave sterilization were found to be the best treatment techniques with minimal environmental impact. A circular economy model with the concept of waste minimizaton, and value recovery was proposed for sustainable medical waste management. This study suggests proper training on healthcare waste management, proposing strict regulations, structured research allocation, and implementation of public-private partnerships to reduce, and control medical waste generation for creating a sustainable medical waste management system in Bangladesh.

Effective Adsorption and Removal of Doxorubicin from Aqueous Solutions Using Mesostructured Silica Nanospheres: Box-Behnken Design Optimization and Adsorption Performance Evaluation

The aim of this study is to evaluate the efficacy of mesoporous silica nanospheres as an adsorbent to remove doxorubicin (DOX) from aqueous solution. The surface and structural properties of mesoporous silica nanospheres were investigated using BET, SEM, XRD, TEM, ζ potential, and point of zero charge analysis. To optimize DOX removal from aqueous solution, a Box-Behnken surface statistical design (BBD) with four times factors, four levels, and response surface modeling (RSM) was used. A high amount of adsorptivity from DOX (804.84 mg/g) was successfully done under the following conditions: mesoporous silica nanospheres dose = 0.02 g/25 mL; pH = 6; shaking speed = 200 rpm; and adsorption time = 100 min. The study of isotherms demonstrated how well the Langmuir equation and the experimental data matched. According to thermodynamic characteristics, the adsorption of DOX on mesoporous silica nanospheres was endothermic and spontaneous. The increase in solution temperature also aided in the removal of DOX. The kinetic study showed that the model suited the pseudo-second-order. The suggested adsorption method could recycle mesoporous silica nanospheres five times, with a modest reduction in its ability for adsorption. The most important feature of our adsorbent is that it can be recycled five times without losing its efficiency.

Valorization of biowastes for clean energy production, environmental depollution and soil fertility

The mother earth is a source of natural resources that, in conjunction with anthropogenic activities, generates a wide spectrum of different biowastes. These biomaterials can be used as low-cost raw feedstock to produce bioenergy, value-added products, and other commodities. However, the improper management and disposal of these biowastes can generate relevant environmental impacts. Consequently, it is imperative to explore alternative technologies for the valorization and exploitation of these wastes to obtain benefits for the society. This review covers different aspects related to valorization of biowastes and their applications in water pollution, soil fertility and green energy generation. The classification and characteristics of different biowastes (biosolids, animal wastes and effluents, plant biomass, wood and green wastes) including their main generation sources are discussed. Different technologies (e.g., pyrolysis, hydrothermal carbonization, anaerobic digestion, gasification, biodrying) for the transformation and valorization of these residues are also analyzed. The application of biowastes in soil fertility, environmental pollution and energy production are described and illustrative examples are provided. Finally, the challenges related to implement low-cost and sustainable biowaste management strategies are highlighted. It was concluded that reliable simulation studies are required to optimize all the logistic stages of management chain of these residues considering the constraints generated from the economic, environmental and social aspects of the biowaste generation sources and their locations. The recollection and sorting of biowastes are key parameters to minimize the costs associated to their management and valorization. Also, the concepts of Industry 4.0 can contribute to achieve a successful commercial production of the value-added products obtained from the biowaste valorization. Overall, this review provides a general outlook of biowaste management and its valorization in the current context of circular economy.

Facile fabrication of Mxene coated metal mesh-based material for oil /water emulsion separation

The present study was set out to synthesize Mxene (Ti₃C₂Tx) and functionalized Mxene nanoparticles and fabricating Mxene coated stainless steel meshes using the dip-coating methodology to investigate the capability of Mxene nanoparticles in oil-water emulsion separation. O/W mixtures separation with extraordinary 100% of effectiveness and purity using designed grid was observed. Most specifically, Mxene fabricated mesh showed good resistance to corrosive solutions of HCl and NaOH and was used to separate O/W at harsh medium condition with a separation efficiency of more than after 96.0% replicated experiment, and its super-hydrophilicity persisted in spite of the air exposure condition, extreme fluids immersion, or abrasion. The XRD, FTIR, SEM, FESEM, AFM and DLS tests have been performed to characterize the Mxene coating and its effectiveness on the O/W separation. These analyzes confirm the fabricated tough super-hydrophilic stainless-steel mesh explored in this research can basically be utilized as a highly effective useful mesh for O/W fluid separation under different sever circumstances. The XRD pattern of the resulting powder shows a single phase formation of Mxene, the SEM and FESEM images confirms creation of coated mesh with approximately 30 µ pore size, AFM tests verify that structures (both in nm and µm sizes) formation with high RMS (Root Mean Square) roughness values of 0.18 µm and 0.22 µm for Mxene and carboxylic-Mxene coated mesh. The DLS tests prove the droplets size distribution of emulsion has been augmented after several O/W separation, which confirmed the coagulating mechanism of oil droplets once contacting with the Mxene and carboxylic Mxene coatings of the mesh.

Concepts of circular economy for sustainable management of electronic wastes: challenges and management options

The electronic and electrical industrial sector is exponentially growing throughout the globe, and sometimes, these wastes are being disposed of and discarded with a faster rate in comparison to the past era due to technology advancements. As the application of electronic devices is increasing due to the digitalization of the world (IT sector, medical, domestic, etc.), a heap of discarded e-waste is also being generated. Per-capita e-waste generation is very high in developed countries as compared to developing countries. Expansion of the global population and advancement of technologies are mainly responsible to increase the e-waste volume in our surroundings. E-waste is responsible for environmental threats as it may contain dangerous and toxic substances like metals which may have harmful effects on the biodiversity and environment. Furthermore, the life span and types of e-waste determine their harmful effects on nature, and unscientific practices of their disposal may elevate the level of threats as observed in most developing countries like India, Nigeria, Pakistan, and China. In the present review paper, many possible approaches have been discussed for effective e-waste management, such as recycling, recovery of precious metals, adopting the concepts of circular economy, formulating relevant policies, and use of advance computational techniques. On the other hand, it may also provide potential secondary resources valuable/critical materials whose primary sources are at significant supply risk. Furthermore, the use of machine learning approaches can also be useful in the monitoring and treatment/processing of e-wastes. HIGHLIGHTS: In 2019, ~ 53.6 million tons of e-wastes generated worldwide. Discarded e-wastes may be hazardous in nature due to presence of heavy metal compositions. Precious metals like gold, silver, and copper can also be procured from e-wastes. Advance tools like artificial intelligence/machine learning can be useful in the management of e-wastes.

Encapsulated laccase in bimetallic Cu/Zn ZIFs as stable and reusable biocatalyst for decolorization of dye wastewater

Laccase have received extensive attention in pollutant degradation, but its practical viability is largely affected by the poor stability, easy inactivation and difficulty in recycling for the present. Enzyme immobilization offers enhanced enzyme stability and constructs a synergistic system for the efficient adsorption and degradation of pollutants. In this study, bimetallic Cu/Zn ZIFs were synthesized by co-precipitation method as the protective carrier for laccase. Lac@Cu-ZIF-90 exhibited a good protective effect on laccase and showed a high operational stability in various interfering environments. Free laccase was completely inactivated at pH 7.0 but Lac@Cu-ZIF-90 could maintain 50.0 % activity. Benefiting from the encapsulation of laccase and porous structure of Cu-ZIF-90, the Lac@Cu-ZIF-90 exhibited decolorization efficiency for dye wastewater. More importantly, the Lac@Cu-ZIF-90 could be recovered from the dye solution and re-used to adsorb and degrade the synthetic dye for multiple times, its removal rate for reactive deep green was only decreased about 10.8 % after five cycles. This work reveals that the Cu-ZIF-90 provides a favorable environment for laccase and as a protective layer to relieve the conformation change, which provides an efficient strategy to decolorize dye wastewater. Therefore, Cu-ZIF-90 promises applications as enzymes encapsulation has great potential in water remediation.

Building of soft-hard compound brush in porous PVA/NH2@TAtZnO plural gel and the high-efficiency anti-interference removal on Pb(II)

In order to promote the heavy metal ions removal of porous gel adsorbent and protect the adsorbent from other pollutants in wastewater, the tetrapod ZnO whiskers (tZnO) modified by amino-chain brush was introduced into the polyvinyl alcohol (PVA) matrix to prepare the PVA/NH₂@TAtZnO composites with brush structure for toxic Pb(II) removal. The adsorption property, adsorption process and adsorption mechanism were studied by adsorption isotherms, adsorption kinetics, adsorption thermodynamics, SEM-EDS analysis and XPS analysis. And the anti-interference ability and anti-interference mechanism were researched by SEM-EDS analysis and XPS analysis. It was found that the PVA/NH₂@TAtZnO composites displayed a soft-hard compound pore-brush structure and showed a good selective adsorption on Pb(II). The research of isotherms and kinetics indicated that the adsorption process was fitted well to Langmuir model and pseudo-second-order model, respectively, and the research of thermodynamics revealed the endothermic nature. The adsorption mechanism was inferred as the combination of predominant chemisorption and subsidiary physisorption. Comparing with the neat PVA matrix, the PVA/NH₂@TAtZnO composites displayed a good anti-interference property on Pb(II) adsorption and showed an alleviative clogging pore-canal structure in the wastewater with SiO₂ NPs or PAC flocculants. The anti-interference intensity ΔQ and anti-interference factor χ were proposed to reflect the anti-interference ability of this adsorbent which was promoted with the increasing amino brush length or density. By the analysis of SEM-EDS and XPS, the anti-interference mechanism was explored as the steric-hinerance effect of tZnO hard brush to suspended SiO₂ NPs pollutant and the coordination effect of functional amino soft brush to soluble PAC pollutant. Besides, the prepared PVA/NH₂@TAtZnO adsorbent possessed a good reusability under multiple adsorption-desorption processes and also presented a well applicability in real water matrix. The research indicated the huge potential of prepared PVA/NH₂@TAtZnO adsorbent in heavy metal ions removal.

Sustainability for wastewater treatment: bioelectricity generation and emission reduction

This review covers the technological measures of a self-sustainable anaerobic up-flow sludge blanket (UASB) system compared with an aerobic activated sludge process (ASP) for wastewater treatment plants (WWTPs). The ASP requires a huge amount of electricity and chemicals and also results in the emission of carbon. The UASB system, instead, is based on greenhouse gas (GHG) emission reduction and is associated with biogas production for cleaner electricity. WWTPs including the ASP system are not sustainable due to the massive financial power required for clean wastewater. When the ASP system was used, the amount of production was estimated to be 10658.98 tonnes CO₂eq-d^- of carbon dioxide. Whereas it was 239.19 tonnes CO₂eq-d^-1 with the UASB. The UASB system is advantageous over the ASP system as it has a high production of biogas, needs low maintenance, yields a low amount of sludge, and is also a source of electricity that can be used as a power source for the WWTPs. Also, the UASB system produces less biomass, and this helps in reducing costs and maintaining work. Moreover, the aeration tank of the ASP needs 60% of energy distribution; on the other hand, the UASB consumes less energy, approximately 3-11%.

Evolution of pore structure and radon exhalation characterization of porous media grouting

Cracks and pores are considered as major sources of radon. Cement is widely used as a grouting material in mines, tunnels, and other projects for reinforcement, seepage prevention, and water plugging. This paper mainly experimentally studied the correlation between the radon exhalation rate of the porous medium after grouting and the sand grain diameter, grouting pressure, and slurry water-cement ratio. The pore characteristics of the samples before and after grouting were also studied based on the low field nuclear magnetic resonance (LF-NMR). The findings of the study show that the porosity of samples increases after the superfine cement solidification with an increase in the water-cement ratio, and the radon exhalation rate is proportional to porosity, the radon exhalation rate increases by 0.0005 Bq·m-2/s at W/C = 1.5, and by 0.0017 Bq·m^-2/s at W/C = 2 increases, in comparison to the W/C = 1.The radon exhalation rate of porous media gradually increased after grouting in response to an increase in grouting pressure and the water-cement ratio. The radon exhalation rate of the porous media with larger pores was relatively higher and exhibited a positive correlation with the volume of micropores in porous media，the correlations of coarse, medium and fine media are 0.815, 0.826, and 0.859. The change in pore structure has an influence on radon exhalation. Although grouting changes the pore structure and reduces the connectivity between internal pores, the micropores generated after cement slurry solidification improves the radon exhalation rate by providing new channels, When the water-cement ratio is 1.5 and the grouting pressure is 1.5 MPa, the radon exhalation rate of porous media is 0.00273 Bq·m^-2/s. The research results serve as a reference basis for the evaluation of the impact of rock masses on grouting reinforcement and pore sealing.

Sustainable futures in agricultural heritage: Geospatial exploration and predicting groundwater-level variations in Barind tract of Bangladesh

Groundwater resources are one of the essential aspects of achieving self-sufficiency in a country's agricultural production, poverty alleviation, and socioeconomic development, particularly in agricultural heritage management and practices. In the Barind Tract in Bangladesh, groundwater levels have steadily declined due to growing irrigation demand. Surface water sources become scarce during the dry season, and groundwater levels fall to levels that make minimum cultivation challenging. In these circumstances, determining the current status of groundwater is key to any action in the future. This study investigated the existing geospatial pattern and critical zone of groundwater level in Chapainawabganj District, a significant area of the Barind Tract of Bangladesh, and predicted future groundwater levels considering multiple factors. Kriging, a sophisticated geostatistical method, was performed to examine the geographical pattern and groundwater variations, and time series analysis was employed to determine data trends and make future projections. The current study used groundwater level data from 23 monitoring stations over 10 years (2009-2018). Exponential, Gaussian, and Spherical models were cross-matched here for the best predictor model in four fitness measures to determine groundwater concentrations (RMSE, ME, RMSS, ASE), and Box-Jenkins ARIMA (3,1,0) was found best-fit for predictions, and variance estimation. Likewise, cross-validation has been assessed for the accuracy of anticipated results across spatial scales. Although more research is needed to identify the underlying mechanisms, critical zones, and their pattern of modification, possible recharge zones and their locations have been identified. Future groundwater levels, critical zones, and recharge locations have been indicated for the research area and potential recommendations.

Improving the rate capacity and cycle stability of FeP anodes for lithium-ion batteries via in situ carbon encapsulation and copper doping

FeP has emerged as an appealing anode material for lithium-ion batteries (LIBs) thanks to its high theoretical capacity, safe voltage platform and rich resources. Nevertheless, sluggish charge transfer kinetics, inevitable volume expansion and easy agglomeration of active materials limit its practical applications. Here, novel Cu-doped FeP@C was synthesized by a synergistic strategy of metal doping and in situ carbon encapsulation. The optimized Cu-doped FeP@C anode demonstrates a highly reversible specific capacity (920 mAh g^-1 at 0.05 A g^-1), superb rate performance (345 mAh g^-1 at 5 A g^-1) and long-term cycle stability (340 mAh g^-1 at 2 A g^-1 after 600 cycles). The electrochemical mechanism was investigated by cyclic voltammetry, kinetic analysis and DFT calculations. The results reveal that carbon frameworks can improve the conductivity and slow down the volume expansion, with highly dispersed FeP facilitating Li-ion migration during the charge and discharge processes. Additionally, Cu doping leads to rearrangement of the charge density and an additional lattice distortion in FeP, which boosts the electron mobility and enriches the surface-active sites, promoting electrochemical reaction and charge storage. This study presents a feasible and effective design for developing transition metal phosphate (TMP) anodes for high-performance LIBs.

Mixed-valence molybdenum oxide as a recyclable sorbent for silver removal and recovery from wastewater

Silver ions in wastewater streams are a major pollutant and a threat to human health. Given the increasing demand and relative scarcity of silver, these streams could be a lucrative source to extract metallic silver. Wastewater is a complex mixture of many different metal salts, and developing recyclable sorbents with high specificity towards silver ions remains a major challenge. Here we report that molybdenum oxide (MoO_x) adsorbent with mixed-valence (Mo(V) and Mo(VI)) demonstrates high selectivity (distribution coefficient of 6437.40 mL g^-1) for Ag⁺ and an uptake capacity of 2605.91 mg g^-1. Our experimental results and density functional theory calculations illustrate the mechanism behind Ag⁺ adsorption and reduction. Our results show that Mo(V) species reduce Ag⁺ to metallic Ag, which decreases the energy barrier for subsequent Ag⁺ reductions, accounting for the high uptake of Ag⁺ from wastewater. Due to its high selectivity, MoO_x favorably adsorbs Ag⁺ even in the presence of interfering ions. High selective recovery of Ag⁺ from wastewater (recovery efficiency = 97.9%) further supports the practical applications of the sorbent. Finally, MoO_x can be recycled following silver recovery while maintaining a recovery efficiency of 97.1% after five cycles. The method is expected to provide a viable strategy to recover silver from wastewater.

Investigations of microwave absorption performance of bi-layer absorber composed of FeWO4 & BiVO4 nanocomposite powder in 2-18 GHz

Optimization necessitates every feature to be scrutinized associated with enhancement for microwave absorption. So, interplay between simulation and experiment is a significant aspect to find optimal findings in this regard. Herein, microwave absorption characteristics of as-prepared FeWO₄ and BiVO₄ nanomaterials were investigated by preparing mono layer and bilayer samples. For the bilayer samples, simulation technique was used to regulate microwave absorption efficiency. Using simulation technique, bilayer sample has achieved a minimum reflection loss (RL_min) of -42 dB with BiVO₄ as a top layer (0.6 mm thickness) and FeWO₄ as a bottom layer (0.8 mm thickness) with effective absorption Bandwidth (EAB) of 13 GHz (15-2 GHz) at 8.2 GHz frequency. The results show that the layered architecture of the absorbent is substantially responsible for its remarkable microwave absorption efficiency. Simulated results of the bilayer sample were also verified with experimental findings. This work provides a facile synthesis route, novel insights into the design of bilayer absorbent as well as simulation and experimental support for high-performance microwave bilayer absorber.

Synthesis of hybrid framework of tenorite and octahedrally coordinated aluminosilicate for the robust adsorption of cationic and anionic dyes

Adsorption is an important process for the industrial dye effluent treatment. Many adsorbents are employed such as activated carbon, metal oxide, molecular sieves etc. All those adsorbents are having their own setbacks like longer adsorption time and lower adsorption capacity. So development of fast adsorption and higher adsorption capacity is very much essential. In this view, we synthesized hybrid crystal system of tenorite and aluminosilicate framework (CuO@AS) for the faster adsorption. It is characterized by FT-IR, HRTEM and WAXRD. WAXRD proved the hybridization of two crystal systems viz tenorite & alumina in monoclinic phase and silica in trigonal phase. The crystal structure drawn based on the WAXRD data. It is observed that the tenorite and aluminosilicate framework are separate, but they are interlinked through Cu-O-Al and Cu-O-Si bond. This interconnection makes the aluminium in six coordination and Cu in four coordination. Aluminium and copper has 3 and 2 Brønsted acid sites respectively. Moreover, copper has three more OH group, so totally 5 H⁺ and 3 OH^- sites in copper and aluminium are responsible for the faster adsorption with high adsorption capacity compared to reported literature. To test the adsorption tendency, Victoria Blue (VB) and Metanil Yellow (MY) dyes are employed at room temperature. The rate constant of Pseudo-second order kinetics for the VB and MY are 0.002462 g mg^-1 min^-1 and 0.001619 g mg^-1 min^-1 which indicated faster adsorption of VB than MY. Moreover, total adsorption capacity for VB (636 mg/g) is higher than MY (52 mg/g). This is due to the hybridization of tenorite and aluminosilicate. Thermodynamic data such as ΔG°, ΔH° and ΔS° revealed that the adsorption is spontaneous, chemisorption and highly disordered in the adsorbent-adsorbate interface. This disorderness is due to the disordered pores present in the material.

Tumor microenvironment responded naturally extracted FOF1-ATPase loaded chromatophores for antitumor therapy

Tumor microenvironment (TME) plays an important role in the growth, invasion, and metastasis of tumor cells. The pH of TME is more acidic in solid tumors than in normal tissues. Although targeted delivery in TME has progressed, the complex and expensive construction of delivery systems has limited their application. F_OF1-ATP synthase (F_OF1-ATPase) is a rotation molecular motor found in bacteria, chloroplasts, and mitochondria. Here, F_OF1-ATPase loaded chromatophores (chroma) isolated from thermophilic bacteria were extracted and utilized as a new delivery system targeting TME for the first time. Curcumin as model drug was successfully loaded by a filming-rehydration ultrasonic dispersion method to prepare a curcumin-loaded chroma delivery system (Cur-Chroma). The mobility and propensity distributions of Cur-Chroma reveal its specific pH-sensitive targeting driven by the transmembrane proton kinetic potential, demonstrating its distinct distribution in the TME and more favorable targeting delivery. Cellular uptake experiments indicated that Cur-Chroma entered cells through grid pathway-mediated endocytosis. In vivo studies have shown that Cur-Chroma can specifically target tumor tissue and effectively inhibit tumor growth with good safety. Curcumin's bioavailability and anti-tumor effects were significantly improved. These studies demonstrate that ATPase-loaded chromatophores are potentially ideal vehicles for anti-tumor drug delivery and have promising applications.

CoO embedded porous biomass-derived carbon as dual-functional host material for lithium-sulfur batteries

A new strategy is developed to fabricate sulfur electrode by infusing sulfur into a conductive biochar decorated with highly dispersed CoO nanoparticles. The loading of the CoO nanoparticles, as the active sites for reactions, is efficiently increased by using the microwave-assisted diffusion method. It is demonstrated that biochar can serve as an excellent conductive framework to effectively activate sulfur. Simultaneously, the CoO nanoparticles possessing excellent capability to adsorb polysulfides can remarkably alleviate the dissolution of polysulfides, and greatly enhance the conversion kinetics between the polysulfides and Li₂S₂/Li₂S in the charge/discharge processes. The sulfur electrode dual-functionalized with biochar and CoO nanoparticles exhibits excellent electrochemical performance, including high initial discharge specific capacity of 930.5 mAh g^-1 and low capacity decay rate of 0.069 % per cycle during 800 cycles at 1C rate. It is particularly interesting that the CoO nanoparticles distinctively enhance the Li⁺ diffusion during the charge process, endowing the material with excellent high-rate charging performance. This could be beneficial for the development of Li-S batteries with fast charging feature.

Enhanced Adsorption and Evaluation of Tetracycline Removal in an Aquatic System by Modified Silica Nanotubes

In the present study, a nanocomposite adsorbent based on mesoporous silica nanotubes (MSNTs) loaded with 3-aminopropyltriethoxysilane (3-APTES@MSNTs) was synthesized. The nanocomposite was employed as an effective adsorbent for the adsorption of tetracycline (TC) antibiotics from aqueous media. It has an 848.80 mg/g maximal TC adsorption capability. The structure and properties of 3-APTES@MSNT nanoadsorbent were detected by TEM, XRD, SEM, FTIR, and N₂ adsorption-desorption isotherms. The later analysis suggested that the 3-APTES@MSNT nanoadsorbent has abundant surface functional groups, effective pore size distribution, a larger pore volume, and a relatively higher surface area. Furthermore, the influence of key adsorption parameters, including ambient temperature, ionic strength, initial TC concentration, contact time, initial pH, coexisting ions, and adsorbent dosage, had also been investigated. The 3-APTES@MSNT nanoadsorbent's ability to adsorb the TC molecules was found to be more compatible with Langmuir isothermal and pseudo-second-order kinetic models. Moreover, research on temperature profiles pointed to the process' endothermic character. In combination with the characterization findings, it was logically concluded that the 3-APTES@MSNT nanoadsorbent's primary adsorption processes involved interaction, electrostatic interaction, hydrogen bonding interaction, and the pore-fling effect. The synthesized 3-APTES@MSNT nanoadsorbent has an interestingly high recyclability of >84.6 percent up to the fifth cycle. The 3-APTES@MSNT nanoadsorbent, therefore, showed promise for TC removal and environmental cleanup.

Phosphonation of Alginate-Polyethyleneimine Beads for the Enhanced Removal of Cs(I) and Sr(II) from Aqueous Solutions

Although Cs(I) and Sr(II) are not strategic and hazardous metal ions, their recovery from aqueous solutions is of great concern for the nuclear industry. The objective of this work consists of designing a new sorbent for the simultaneous recovery of these metals with selectivity against other metals. The strategy is based on the functionalization of algal/polyethyleneimine hydrogel beads by phosphonation. The materials are characterized by textural, thermo-degradation, FTIR, elemental, titration, and SEM-EDX analyses to confirm the chemical modification. To evaluate the validity of this modification, the sorption of Cs(I) and Sr(II) is compared with pristine support under different operating conditions: the pH effect, kinetics, and isotherms are investigated in mono-component and binary solutions, before investigating the selectivity (against competitor metals) and the possibility to reuse the sorbent. The functionalized sorbent shows a preference for Sr(II), enhanced sorption capacities, a higher stability at recycling, and greater selectivity against alkali, alkaline-earth, and heavy metal ions. Finally, the sorption properties are compared for Cs(I) and Sr(II) removal in a complex solution (seawater sample). The combination of these results confirms the superiority of phosphonated sorbent over pristine support with promising performances to be further evaluated with effluents containing radionuclides.

Subcellular distribution, chemical forms of cadmium and rhizosphere microbial community in the process of cadmium hyperaccumulation in duckweed

Duckweed is a newly reported Cd hyperaccumulator that grow rapidly; however, little is known about its tolerance and detoxification mechanisms. In this study, we investigated the tissue, subcellular, and chemical form distribution of the Cd in duckweed and studied the influences of Cd on duckweed growth, ultrastructure, and rhizosphere microbial community. The results showed that Cd could negatively affect the growth of duckweed and shorten the root length. More Cd accumulated in the roots than in the leaves, and Cd was transferred from the roots to the leaves with time. During 12-24 h, Cd mainly existed in the cell wall fraction (2.05 %-95.52 %) and the organelle fraction (5.03 %-97.80 %), followed the soluble fraction (0.14 %-16.98 %). Over time, the proportion of Cd in the organelles increased (46.64 %-92.83 %), exceeding that in the cell wall (6.79 %-66.23 %), which indicated that duckweed detoxification mechanism may be related to the retention of cell wall and vacuole. The main chemical form of Cd was the NaCl-extracted state (30.15 %-88.66 %), which was integrated with pectate and protein. With increasing stress concentration and time, the proportion of the HCl-extracted state and HAc-extracted state increased, and they were low-toxic Cd oxalate and Cd phosphate, respectively. Cd damaged the ultrastructure of cells such as chloroplasts and mitochondria and inhibited the diversity of microbial communities in the duckweed rhizosphere; however, the dominant populations that could tolerate heavy metals increased. It was speculated that duckweed distributed Cd in a less toxic chemical form in a less active location, mainly through retention in the root cell wall and sequestration in the leaf vacuoles, and is dynamically adjusted. The rhizosphere microbial communities tolerate heavy metals may also be one of the mechanisms by which duckweed can tolerate Cd. This study revealed the mechanism of duckweed tolerance and detoxification of Cd at the molecular level and provides a theoretical basis for further development of duckweed.

The efficient adsorption of tetracycline from aqueous solutions onto polymers with different N-vinylpyrrolidone contents: equilibrium, kinetic and dynamic adsorption

Extensive use of antibiotics in the world will cause potential risks to human health and ecosystems. The removal of these antibiotics has attracted much attention. Composite materials are growing attention for diverse pollutants separation and removal based on their specific functionality and surface area. In this study, a series of N-vinylpyrrolidone-divinylbenzene polymers (NVPD) with different N-vinylpyrrolidone (NVP) contents were facilely prepared for the adsorption of tetracycline (TC). The effect of polymer surface properties and aqueous solution chemistry (pH, ionic strength, humic acid) on TC adsorption was further studied. The dynamic adsorption and regeneration experiments were also assessed. The results showed that only 25% of NVP was involved in the reaction. When NVP dosage (%) was 75%, polymer (NVPD-g) owned the largest BET surface area (613.23 m2/g) and obtained the maximum TC adsorption capacities (258.76 mg/g). In the kinetic, the adsorption between TC and polymers with NVP was controlled by chemical adsorption and intra-particle diffusion. The TC adsorption process of NVPD-g depended on the contribution of the hydrophobic effect, electrostatic interactions, H-bonding, π-π electron donor-acceptor (EDA) interactions, and cation-π bonding. Moreover, the removal efficiency of TC by NVPD-g was enhanced in the presence of humic acid (HA) in the dynamic adsorption and 1197 BV (2394 mL) of TC simulated wastewater can be treated. These findings suggest that NVPD-g has a potential application in the purification of TC.

A novel static cultivation of bacterial cellulose production from sugar beet molasses: Series static culture (SSC) system

In bacterial cellulose (BC) production, we developed a new static cultivation system named series static culture (SSC) to eliminate air limitation problem encountered in conventional static culture (CSC). In SSC system, the fermentation broth at the bottom of BC pellicle produced in initial culture medium is transferred to the next empty sterile culture medium at the end of a certain fermentation period. This procedure was performed until BC production ceased. Fermentation experiments were carried out using Gluconacetobacter xylinus NRRL B-759 and sugar beet molasses at 30 °C and initial pH 5. Also, some quality parameters of produced BC pellicles were determined. Final pH at the stages of SSC system was higher that of the initial pH due to sugar content (sucrose) of molasses and microorganism used. Total BC production increased with increasing sugar concentration in SSC. As a result, an increase of 22.02 % in BC production was achieved using developed SSC. FT-IR spectra of all BC pellicles produced were typical spectra. The absorption bands at the relevant wavenumbers identify the mode of vibrations of the created chemical bonds arising at the BC surface such as OH, CH, H-O-H, C-O-C, and C-OH. XRD analyses showed that the crystallinity index values of BC obtained from CCS and SSC were high. The form of produced all BC pellicles is generally Cellulose I. Removal of surface moisture and depolymerisation of carbon skeleton were determined from TGA-DTA thermograms. SEM images showed that the BC samples produced had nano-sized cellulose fibrils which were aggregated in fermentation media containing molasses. Finally, the BC samples, especially in molasses media, having high mechanical strength and WHC were found.

Three-dimension titanium phosphate aerogel for selective removal of radioactive strontium(II) from contaminated waters

The effective removal of radioactive strontium (especially ⁹⁰Sr) from nuclear wastewater is crucial to environmental safety. Nevertheless, materials with excellent selectivity in Sr removal remain a challenge since the similarity with alkaline earth metal ions in the liquid phase. In this work, a novel titanium phosphate (TiP) aerogel was investigated for Sr(II) removal from the radioactive wastewater based on the sol-gel method and supercritical drying technique. The TiP aerogel has amorphous, three-dimensional and mesoporous structures with abundant phosphate groups, which was confirmed by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR). The adsorbent exhibited high efficiency and selectivity for the removal of Sr(II) with an extensive distribution coefficient up to 4740.03 mL/g. The adsorption equilibrium reached within 10 min and the maximum adsorption capacity was 373.6 mg/g at pH 5. And the kinetics and thermodynamics data fitted well with the pseudo-second-order model and Langmuir model respectively. It can be attributed to the rapid trapping and slow intraparticle diffusion of Sr(II) inside the mesoporous channels of the TiP aerogel. Furthermore, TiP aerogel exhibited over 80% removal for 50 mg/L Sr²⁺ in real water systems (seawater, lake water and tap water). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy revealed that strong ionic bonding formed during Sr(II) adsorption with the phosphate group on TiP aerogel. These results indicated that TiP aerogel is a promising high-capacity adsorbent for the effective and selective capture of Sr(II) from radioactive wastewater.

Simultaneous electrochemical degradation of pesticides from the aqueous environment using Ti/SnO2-Sb2O3/PbO2/Bi electrode; process modeling and mechanism insight

In this work, modified Bi-PbO₂ electrode was fabricated and employed for simultaneous degradation of fenitrothion (FT), trifluralin (TF), and chlorothalonil (CT) from synthetic and pesticide wastewater through the anodic oxidation process. A novel high-performance liquid chromatography method was developed and optimized to identify the pesticides simultaneously. Quadratic models were developed to investigate the effects of main operating parameters and predict the degradation efficiencies of the treatment processes. The R² of the degradation efficiencies were obtained of 0.9847, 0.9910, and 0.9821 for FT, TF, and CT, respectively, which indicates the degree of conformity between the experimental and the actual values of degradation efficiencies, and the adjusted R² values for the degradation efficiency of FT, TF, and CT in proposed models were 0.9826, 0.9898, and 0.9796, and the values of the predicted R² were 0.9792, 0.9875, and 0.9755, respectively. The maximum degradation efficiencies of 99.7, 100, and 100% obtained for FT, TF, and CT, respectively, under the optimal operating condition of FT, TF, and CT concentration of 10.0, 6.0, and 8.0 mg L^-1, respectively, pH 6.0, the current density 6.0 mA cm^-2, and electrolysis time of 60 min. Chemical oxygen demand removal and energy consumption were 64.7% and 5.1 kWh m^-3. Eventually, the generated intermediates and other produced species of pesticides through the treatment process was evaluated using a gas chromatography-mass spectrometry method, and their degradation pathways were proposed.