Rational synthesis and characterization of highly water stable MOF@GO composite for efficient removal of mercury (Hg2+) from water

Adsorptive removal of heavy metals from aqueous solutions: Progress of adsorbents development and their effectiveness

Increased levels of heavy metals (HMs) in aquatic environments poses serious health and ecological concerns. Hence, several approaches have been proposed to eliminate/reduce the levels of HMs before the discharge/reuse of HMs-contaminated waters. Adsorption is one of the most attractive processes for water decontamination; however, the efficiency of this process greatly depends on the choice of adsorbent. Therefore, the key aim of this article is to review the progress in the development and application of different classes of conventional and emerging adsorbents for the abatement of HMs from contaminated waters. Adsorbents that are based on activated carbon, natural materials, microbial, clay minerals, layered double hydroxides (LDHs), nano-zerovalent iron (nZVI), graphene, carbon nanotubes (CNTs), metal organic frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs) are critically reviewed, with more emphasis on the last four adsorbents and their nanocomposites since they have the potential to significantly boost the HMs removal efficiency from contaminated waters. Furthermore, the optimal process conditions to achieve efficient performance are discussed. Additionally, adsorption isotherm, kinetics, thermodynamics, mechanisms, and effects of varying adsorption process parameters have been introduced. Moreover, heavy metal removal driven by other processes such as oxidation, reduction, and precipitation that might concurrently occur in parallel with adsorption have been reviewed. The application of adsorption for the treatment of real wastewater has been also reviewed. Finally, challenges, limitations and potential areas for improvements in the adsorptive removal of HMs from contaminated waters are identified and discussed. Thus, this article serves as a comprehensive reference for the recent developments in the field of adsorptive removal of heavy metals from wastewater. The proposed future research work at the end of this review could help in addressing some of the key limitations facing this technology, and create a platform for boosting the efficiency of the adsorptive removal of heavy metals.

MOF/graphene oxide based composites in smart supercapacitors: a comprehensive review on the electrochemical evaluation and material development for advanced energy storage devices

The surge in interest surrounding energy storage solutions, driven by the demand for electric vehicles and the global energy crisis, has spotlighted the effectiveness of carbon-based supercapacitors in meeting high-power requirements. Concurrently, metal-organic frameworks (MOFs) have gained attention as a template for their integration with graphene oxide (GO) in composite materials which have emerged as a promising avenue for developing high-power supercapacitors, elevating smart supercapacitor efficiency, cyclic stability, and durability, providing crucial insights for overcoming contemporary energy storage obstacles. The identified combination leverages the strengths of both materials, showcasing significant potential for advancing energy storage technologies in a sustainable and efficient manner. In this research, an in-depth review has been presented, in which properties, rationale and integration of MOF/GO composites have been critically examined. Various fabrication techniques have been thoroughly analyzed, emphasizing the specific attributes of MOFs, such as high surface area and modifiable porosity, in tandem with the conductive and stabilizing features of graphene oxide. Electrochemical characterizations and physicochemical mechanisms underlying MOF/GO composites have been examined, emphasizing their synergistic interaction, leading to superior electrical conductivity, mechanical robustness, and energy storage capacity. The article concludes by identifying future research directions, emphasizing sustainable production, material optimization, and integration strategies to address the persistent challenges in the field of energy storage. In essence, this research article aims to offer a concise and insightful resource for researchers engaged in overcoming the pressing energy storage issues of our time through the exploration of MOF/GO composites in smart supercapacitors.

Green synthesis of Eucalyptus globulus zinc nanoparticles and its use in antimicrobial insect repellent paint formulation in bulk industrial production

Mitigating climate change can be achieved by opting for sustainable, plant-based materials instead of relying on hazardous chemicals that come with various side effects. Various natural plant extracts find widespread application in synthesizing insect-repellent coatings, particularly in industries such as paint manufacturing. The increasing demand for these coatings has led us to find out the effects of different plant extracts for the efficient preparation of paints with more advanced impacts and low cost. For this purpose, zinc nanoparticles of Eucalyptus globulus L. and its extracts were used in this study due to their remarkable biocidal and antimicrobial activities. The extract was prepared by the process of oven-drying and heating followed by their filtration. Then, they were subjected to different phytochemical tests that were performed in which plant material did not contain flavonoids and glycol. The comparison of the size of nanoparticles was visible during the weighing which was found to be 4.451 mg. Advanced characterization techniques like FTIR, UV visible spectroscopy, and particle size analysis were adopted for the analysis of nanoparticles of plant extract. The FTIR analysis of the plant material was reported to lie in the range of 1000-1800 cm-1. On the other hand, the results of UV visible spectroscopy of nanoparticles of plant extract showed absorption peaks around 300 nm. The produced material was integrated into paint formulations to impart insect-repellent and antibacterial characteristics. Painted panels exhibited notable antibacterial efficacy, presenting an inhibition zone of 0.7 cm for Escherichia coli and 0.3 cm for Staphylococcus aureus when utilizing biocide. Plant nanoparticles yielded inhibition zones of 1 and 1.2, while aqueous extract resulted in zones of 0.2 and 0.5, respectively. A thorough evaluation of the paint's color attributes, including ΔL, Δa, Δb, and ΔE, indicated noteworthy differences. The CMC ΔE values from the trials exceeded 1, indicating a substantial change in shade. The batches of paints containing E. globulus extracts and nanoparticles were found to be lighter in color specifically green and yellow colors. Their antimicrobial and insect repellant activity was tested using the mosquitos of Aedes aegypti with an age of 4-5 weeks, revealing that formulations with plant extracts exhibited a 61 % effective period, greater than the 7 % observed in non-biocidal formulations. The paint responded best towards these mosquitoes in terms of repellency and the ultimate target of this study was achieved.

Bulk industrial production of sustainable cellulosic printing fabric using agricultural waste to reduce the impact of climate change

In this research paper, a novel process was developed for reactive printing of cotton fabric, with the objective of producing a high-quality printed fabric that is sustainable, eco-friendly, and low-cost which will ultimately reduce the impact of climate change. The study incorporated substituted tamarind polysaccharide (STP) obtained from agricultural waste, trichloro-ethanoic acid (TCEA), and polyethylene glycol (PEG-400) in the reactive printing paste. Tamarind starch was extracted from the seeds having 72 % yield, and substitution was performed to use it as a thickener in the printing paste. The conventional printing system was formulated with sodium alginate, urea, and sodium bicarbonate at dose levels of 2 %, 15 %, and 2.5 %, respectively, while the modified recipe was formulated with STP and TCEA at 5 % and 3 % dose levels, respectively along with varying doses of PEG-400 (0 %, 1 %, and 2 %) in novel prints. Various factors such as shade comparison, penetration, staining on the white ground, washing, rubbing, light and perspiration fastness, sharpness of edges, and fabric hardness were evaluated for all the recipes. The study demonstrated that the optimal outcomes were obtained with a 2 % PEG-400 dose level. This study represents a significant contribution to sustainable textile production, as tamarind agriculture waste was used as a raw material, which is an environmentally friendly alternative of sodium alginate that reduces the wastewater load. Additionally, PEG-400 was utilized as a nitrogen-free solubilizing moisture management substitution of urea for printing, while TCEA dissociated at high temperature to make alkaline pH during curing of the printed fabric to replace sodium bicarbonate. This research is a novel contribution to the printing industry, as these three constituents have not been previously used together other than this research group, in the history of reactive printing.

Research progress of MOF-based membrane reactor coupled with AOP technology for organic wastewater treatment

MOF-based catalytic membrane reactor (MCMR), which can simultaneously achieve membrane separation and chemical catalytic degradation in an integrated system, is a cutting-edge technology for effective treatment of organic pollutants in water. The coupling of MCMR and advanced oxidation process (AOP) not only significantly improves the pollutant removal efficiency but also inhibits the membrane pollution through self-cleaning effect, thus improving the stability of MCMR. This paper reviews different MCMR systems combined with photocatalysis, Fenton oxidation, and persulfate activation, elucidates the reaction mechanism, discusses key issues to improve system effectiveness, and suggests future challenges and research directions.

Terbium-based dual-ligand metal organic framework by diffusion method for selective and sensitive detection of danofloxacin in aqueous medium

A water-dispersible Tb(III)-based metal organic framework (TBP) was produced by diffusion technique using benzene-1,3,5-tricarboxylic acid (BTC) and pyridine as easily accessible ligands at low cost. The as-synthesized TBP with a crystalline structure and rod-shaped morphology has exhibited thermal stability up to 465 °C. Elemental analysis confirmed the presence of carbon, oxygen, nitrogen, and terbium in the synthesized MOF. TBP was used as a fluorescent probe for detection of danofloxacin (DANO) in an aqueous medium with significant enhancement of fluorescence intensity as compared to various fluoroquinolone antibiotics (levofloxacin (LEVO), ofloxacin (OFLO), norfloxacin (NOR), and ciprofloxacin (CIPRO)) with a low detection limit of 0.45 ng/mL (1.25 nm). The developed method has successfully detected DANO rapidly (i.e., response time = 1 min) with remarkable recovery (97.66-101.96%) and a relative standard deviation (RSD) of less than 2.2%. Additionally, TBP showcased good reusability up to three cycles without any significant performance decline. The in-depth mechanistic studies of the density functional theory (DFT) calculations and mode of action revealed that hydrogen bonding interactions and photo-induced electron transfer (PET) are the major factors for the turn-on enhancement behavior of TBP towards DANO. Thus, the present work provides the quick and precise identification of DANO using a new fluorescent MOF (TBP) synthesized via a unique and facile diffusion technique.

Recent advancements in non-enzymatic electrochemical sensor development for the detection of organophosphorus pesticides in food and environment

Organophosphorus Pesticides (OPPs) are among the extensively used pesticides throughout the world to boost agricultural production. However, persistent residues of these toxic pesticides in various vegetables, fruits, and drinking water poses detrimental health effects. Consequently, the rapid monitoring of these harmful chemicals through simple and cost-effective methods has become crucial. In such an instance, electrochemical methods offer simple, rapid, sensitive, reproducible, and affordable detection pathways. To overcome the limitations associated with electrochemical enzymatic sensors, non-enzymatic sensors have emerged as promising and simpler alternatives. The non-enzymatic sensors have demonstrated superior activity, reaching detection limit up to femto (10-15) molar concentration in recent years, leveraging higher selectivity obtained through the molecularly imprinted polymers, synergistic effects between carbonaceous nanomaterials and metals, metal oxide alloys, and other alternative approaches. Herein, this review paper provides an overview of the recent advancements in the development of non-enzymatic electrochemical sensors for the detection of commonly used OPPs, such as Chlorpyrifos (CHL), Diazinon (DZN), Malathion (MTN), Methyl parathion (MP) and Fenthion (FEN). The design method of the electrodes, electrode functioning mechanism, and their analytical performance metrics, such as limit of detection, sensitivity, selectivity, and linearity range, were reviewed and compared. Furthermore, the existing challenges within this rapidly growing field were discussed along with their potential solutions which will facilitate the fabrication of advanced and sustainable non-enzymatic sensors in the future.

Synthesis of a novel multifunctional organic-inorganic nanocomposite for metal ions and organic dye removals

In this study, we used solvent assisted mechano-synthesis strategies to form multifunctional organic-inorganic nanocomposites capable of removing both organic and inorganic contaminants. A zeolite X (Ze) and activated carbon (AC) composite was synthesized via state-of-the-art mechanical mixing in the presence of few drops of water to form Ze/AC. The second composite (Ze/L/AC) was synthesized in a similar fashion, however this composite had the addition of disodium terephthalate as a linker. Both materials, Ze/AC and Ze/L/AC, were characterized using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Powdered X-ray diffraction (P-XRD), Fourier-transform infrared spectrometry (FTIR), Accelerated Surface Area and Porosimetry System (ASAP), and thermal gravimetric analysis (TGA). The SEM-EDS displayed the surface structure and composition of each material. The sodium, oxygen and carbon contents increased after linker connected Ze and AC. The P-XRD confirmed the crystallinity of each material as well as the composites, while FTIR indicated the function groups (C=C, O-H) in Ze/L/AC. The contaminant adsorption experiments investigated the effects of pH, temperature, and ionic strength on the adsorption of methylene blue (MB) and Co(II) for each material. In MB adsorption, the first-order reaction rate of Ze/L/AC (0.02 h-1) was double that of Ze/AC (0.01 h-1). The reaction rate of Ze/L/AC (4.8 h-1) was also extraordinarily higher than that of Ze/AC (0.6 h-1) in the adsorption of Co(II). Ze/L/AC composite achieved a maximum adsorption capacity of 44.8 mg/g for MB and 66.6 mg/g for Co(II) ions. The MB adsorption of Ze/AC and Ze/L/AC was best fit in Freundlich model with R2 of 0.96 and 0.97, respectively, which indicated the multilayer adsorption. In the Co(II) adsorption, the data was highly fit in Langmuir model with R2 of 0.94 and 0.92 which indicated the monolayer adsorption. These results indicated both materials exhibited chemisorption. The activation energy of Ze/L/AC in MB adsorption (34.9 kJ mol-1) was higher than that of Ze/L/AC in Co (II) adsorption (26 kJ mol-1).

The Influence of Oxidation and Nitrogenation on the Physicochemical Properties and Sorption Capacity of Activated Biocarbons Prepared from the Elderberry Inflorescence

The main objective of the study was to prepare a series of new activated biocarbons by means of physical and chemical activation of elderberry inflorescence. The influence of carbon matrix nitrogenation/oxidation on the physicochemical properties and sorption abilities of the carbonaceous materials was investigated. The impact of initial dye concentration, pH and temperature of the system on methylene blue and rhodamine B removal efficiency was checked. It was shown that activation of elderberry inflorescences with CO₂ or H₃PO₄, and their further modification by introducing nitrogen or oxygen functional groups, allowed us obtain a wide range of materials that differ significantly in terms of the chemical nature of the surface, degree of specific surface development and the type of porous structure generated. The samples prepared by chemical activation proved to be very effective in terms of cationic dyes adsorption. The maximum sorption capacity toward methylene blue and rhodamine B reached the level of 277.8 and 98.1 mg/g, respectively. A better fit to the experimental data was achieved with a Langmuir isotherm than a Freundlich one. It was also shown that the efficiency of methylene blue and rhodamine B adsorption from aqueous solutions decreased with increasing temperature of the system.

Antibacterial and antioxidant activities of curcumin/Zn metal complex with its chemical characterization and spectroscopic studies

Curcumin is an active component of the rhizome turmeric. Curcumin/zinc (Cur/Zn) complex was synthesized and characterized using the elemental analysis, the molar conductance, FT-IR, UV-Vis,¹HNMR, scanning (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The molar conductance value is very low, referring to the absence of Cl^- ions inside or outside chelate sphere confirming non electrolytic nature. Based on IR and electronic spectra curcumin C[bond, double bond]O group in enol form chelated to Zn (II) ion. The surface morphology of curcumin chelate with Zn showed elevated in particle size and irregular grains shaped with elongated morphology. Transmission electron microscopy revealed that the curcumin chelate with Zn has spherical black spots like shape with particle size range from (33-97 nm). The antioxidant activities of curcumin and Cur/Zn complex were assessed. Results showed that the Cur/Zn complex showed potent antioxidant activities than curcumin. For antibacterial activity, Curcumin/Zn showed inhibitory effect against both (+ve and -ve) gram bacteria (Bacillus subtilis and Escherichia coli) at very low concentration. Cur/Zn recorded antibacterial and inhibition activity at 0.009 against E. coli and at 0.625 against B. subtilis. Cur/Zn complex showed higher capacity in scavenging the ABTS radical, FARAP capacity and metal chelating activity than curcumin itself and it showed more scavenging and inhibition activity for DPPH. The synthesized complex of Cur/Zn showed potent antioxidant and antibacterial activities than curcumin itself and it may benefit in treatment of aging and degenerative diseases with elevated and excessive production of free radicals.

Olive mill waste sludge: From permanent pollution to a highly beneficial organic biofertilizer: A critical review and future perspectives

Olive mill wastewater sludge (OMWS) is a by-product of the olive extraction process that is attracting substantial attention due to its extremely hazardous effects on aquatic and terrestrial ecosystems. OMWS is a product of the common disposal method of olive oil mill wastewater (OMWW) that accumulates in evaporation ponds. It is estimated that approximately 10 × 10⁶ m³ of OMWS is generated worldwide each year. OMWS is characterized by its significantly variable physicochemical properties and organic pollutant constituents, such as phenols and lipids, which are dependent upon the environmental features of the receiving ponds. Nonetheless, many related studies have recognized the biofertilizer potential of this sludge owing to its high mineral nutrient and organic matter load. OMWS exhibits promising valorization potential in several fields, including agriculture and energy production. Compared to those of OMWW, studies of OMWS are still lacking concerning its composition and characteristics, which are necessary for the future implementation of efficient valorization strategies. The main purpose of this review paper is to fill the gap that exists in the literature by providing a critical analysis of the available data on OMWS production, distribution, characteristics, and properties. Additionally, this work sheds light on important factors affecting OMWS properties, including the variability of the indigenous microbial communities regarding bioremediation. Finally, this review addresses the current and future valorization routes, from detoxification to the development of promising applications in agriculture, energy, and the environment, which could have significant socioeconomic implications for low-income Mediterranean countries.

Rational synthesis, biological screening of azo derivatives of chloro-phenylcarbonyl diazenyl hydroxy dipyrimidines/thioxotetrahydropyrimidines and their metal complexes

Herein, a new series of azo ligands HL-1 (5-(2-chloro-6-(phenylcarbonyl)phenyl)diazenyl)-6-hydroxydihydropyrimidines-2,4dione), HL-2 (5-(2-chloro-6-(phenylcarbonyl)phenyl)diazenyl)-6-hydroxy-2-thioxottetrahydropyrimidin-4one), HL-3 (5-(2,4-dichloro-6-(phenylcarbonyl)phenyl) diazenyl)-6-hydroxydihydropyrimidines-2,4dione), HL-4 (5-(2,4-dichloro-6-(phenylcarbonyl) phenyl)diazenyl)-6-hydroxy-2-thioxotetrahydropyrimidin-4one) and their metal complexes with Cu(II) & Ni(II) were synthesized successfully having excellent yield, in reproducible conditions and for structure elucidation different advance spectroscopic techniques (FTIR, ¹H NMR, ¹³C NMR and Mass Spectrometry) were applied. In FTIR analysis, the absence of peak at 3450-3550 cm ^-1 due to -NH₂ and presence of a new peak of N=N at 1390-1520 cm^-1 confirmed synthesis of the ligands. The ¹H NMR spectra of azo ligands showed singlet peak at 11.5-13.5 ppm (Ar-OH) for hydroxyl group and -NH₂ signals disappearance of anilines at 4-5 ppm also gives strong indication for the synthesis of azo compounds. On complexation two most important peaks (M-O, M-N) appeared in all the metal chelates in the range of 400-600 cm^-1 which were not present in any of the ligands, confirmed the formation of complexes. Molecular ion peaks in mass spectra at 273, 388, 407 and 423 m/z value for ligands as well as for complexes at 803, 835, 871 and 904 m/z also give strong indication that proposed ligands and their metal complexes are produced successfully. Biological screening of the synthesized compounds were also carried out against different bacterial strains (E.coli, S.typhi, and B.subtilis), antifungal (C.albicans, A.niger, and C.glabrata) strains and antioxidant activity. From results it was observed that HL-4 and Cu complexes exhibited maximum inhibition against all bacterial and fungal strains as compared to other ligands and standard drug.