Synthesis and characterization of nanocomposite based polymeric membrane (PES/PVP/GO-TiO2) and performance evaluation for the removal of various antibiotics (amoxicillin, azithromycin & ciprofloxacin) from aqueous solution.

The escalating global concern regarding antibiotic pollution necessitates the development of advanced water treatment strategies. This study presents an innovative approach through the fabrication and evaluation of a Polyethersulfone (PES) membrane adorned with GO-TiO2 nanocomposites. The objective is to enhance the removal efficiency of various antibiotics, addressing the challenge of emerging organic compounds (EOCs) in water systems. The nanocomposite membranes, synthesized via the phase inversion method, incorporate hydrophilic agents, specifically GO-TiO2 nanocomposites and Polyvinylpyrrolidone (PVP). The resultant membranes underwent comprehensive characterization employing AFM, EDS, tensile strength testing, water contact angle measurements, and FESEM to elucidate their properties. Analysis revealed a substantial improvement in the hydrophilicity of the modified membranes attributed to the presence of hydroxyl groups within the GO-TiO2 structure. AFM images demonstrated an augmentation in surface roughness with increasing nanocomposite content. FESEM images unveiled structural modifications, leading to enhanced porosity and augmented water flux. The pure water flux elevated from 0.980 L/m2.h-1 for unmodified membranes to approximately 6.85 L/m2.h-1 for membranes modified with 2 wt% nanocomposites. Membrane performance analysis indicated a direct correlation between nanocomposite content and antibiotic removal efficiency, ranging from 66.52% to 89.81% with 4 wt% nanocomposite content. Furthermore, the nanocomposite-modified membrane exhibited heightened resistance to fouling. The efficacy of the membrane extended to displaying potent antibacterial properties against microbial strains, including S. aureus, E. coli, and Candida. This study underscores the immense potential of GO-TiO2 decorated PES membranes as a sustainable and efficient solution for mitigating antibiotic contamination in water systems. The utilization of nanocomposite membranes emerges as a promising technique to combat the presence of EOC pollutants, particularly antibiotics, in water bodies, thus addressing a critical environmental concern.

Enhancing oil-water emulsion separation via synergistic filtration using graphene oxide-silver oxide nanocomposite-embedded polyethersulfone membrane.

This study introduces an innovative approach for enhancing oil-water emulsion separation using a polyethersulfone (PES) membrane embedded with a nanocomposite of graphene oxide (GO) and silver oxide (AgO). The composite membrane, incorporating PES and polyvinyl chloride (PVC), demonstrates improved hydrophilicity, structural integrity and resistance to fouling. Physicochemical characterization confirms successful integration of GO and AgO, leading to increased tensile strength, porosity and hydrophilicity. Filtration tests reveal substantial improvements in separating various oils from contaminated wastewater, with the composite membrane exhibiting superior efficiency and reusability compared to pristine PES membranes. This research contributes to the development of environmentally friendly oil-water separation methods with broad industrial applications.

Nanomaterials-based biosensor and their applications: A review.

A sensor can be called ideal or perfect if it is enriched with certain characteristics viz., superior detections range, high sensitivity, selectivity, resolution, reproducibility, repeatability, and response time with good flow. Recently, biosensors made of nanoparticles (NPs) have gained very high popularity due to their excellent applications in nearly all the fields of science and technology. The use of NPs in the biosensor is usually done to fill the gap between the converter and the bioreceptor, which is at the nanoscale. Simultaneously the uses of NPs and electrochemical techniques have led to the emergence of biosensors with high sensitivity and decomposition power. This review summarizes the development of biosensors made of NPssuch as noble metal NPs and metal oxide NPs, nanowires (NWs), nanorods (NRs), carbon nanotubes (CNTs), quantum dots (QDs), and dendrimers and their recent advancement in biosensing technology with the expansion of nanotechnology.

A review on the clean-up technologies for heavy metal ions contaminated soil samples.

The soil contamination with heavy metal ions is one of the grave intricacies faced worldwide over the last few decades by the virtue of rapid industrialization, human negligence and greed. Heavy metal ions are quite toxic even at low concentration a swell as non-biodegradable in nature. Their bioaccumulation in the human body leads to several chronic and persistent diseases such as lung cancer, nervous system break down, respiratory problems and renal damage etc. In addition to this, the increased concentration of these metal ions in soil, beyond the permissible limits, makes the soil unfit for further agricultural use. Hence it is our necessity, to monitor the concentration of these metal ions in the soil and water bodies and adopt some better technologies to eradicate them fully. From the literature survey, it was observed that three main types of techniques viz. physical, chemical, and biological were employed to harness the heavy metal ions from metal-polluted soil samples. The main goal of these techniques was the complete removal of the metal ions or the transformation of them into less hazardous and toxic forms. Further the selection of the remediation technology depends upon different factors such as process feasibility/mechanism of the process applied, nature and type of contaminants, type and content of the soil, etc. In this review article, we have studied in detail all the three technologies viz. physical, chemical and biological with their sub-parts, mechanism, pictures, advantages and disadvantages.

Novel supramolecular organo-oil gelators for fast and effective oil trapping: Mechanism and applications.

In this paper, for the sorption of oil from oil polluted soil/water systems, nine new supramolecular organo-oil gelators were synthesized using three distinct diisocyanates and alcohols. The manufactured gelators were characterized using various techniques. The Fourier transform infrared (FTIR) and mass spectra confirmed the successful formation of the oil gelators. The synthesis of the proposed gelators was confirmed by the 1H NMR, which exhibited three singlets that were attributed to an aliphatic side chain containing 29 protons. The scanning electron microscopy (SEM) analysis exhibited porous, sheets, prisms, and fibrous structures for the supramolecular oil gelators. The oil uptake data analysis was subjected to the Langmuir and Freundlich isotherm models which showed the R2 value of 0.99 and a maximum adsorption capacity (qmax) of 45 mLg-1. From the mechanistic point of view, it was proposed that the organo-oil gel initially leads to self-assembly and further entanglements forming the fibers, which finally make a trap for the oil molecules. Among all the nine gelators and different combinations used, the combination of ditetradecyl (TDI 14: DMI14: HMI 14) gelators in the ratio of 1:2:1 exhibited maximum oil uptake of ∼58% initially which further boosted to ∼99% using gasoline as the co-congealed solvent. Interestingly, the complete gelation of the oil from the oil-water mixture was achieved within 30 min of application with high oil recovery. The presented study confirmed that the oil removal by organo-oil gelator is a simple, novel, and facile technique, which could be employed for treating oil-contaminated soil/water mixture.

Novel Hydrophobic Polyvinyl-Alcohol Formaldehyde Sponges: Synthesis, Characterization, Fast and Effective Organic Solvent Uptake from Contaminated Soil Samples.

In the present research work, PVFTX-100, PVFSDS, and PVFT-80 sponges were prepared using polyvinyl-alcohol (PVA) with surfactants triton X-100/sodium dodecyl sulfate (SDS)/Tween 80, respectively, for the removal of organic solvents from polluted soil/water samples. All three obtained sponges were further made hydrophobic using dodecyltrimethoxysilane (DTMS). The prepared sponges were characterized using different spectroscopic techniques and SEM analysis. The peaks obtained near 1050 cm-1 and 790 cm-1 were attributed to Si-O-C and alkyl side chain C-H stretching vibration that confirmed the formation of desired sponges. The SEM images showed the random roughness with a number of protrusions on sponge surfaces, which further played an important role in the absorption and retention of organic solvents molecules. The Sears method was chosen to calculate the surface area and pore volume of all the synthesized sponge samples. Among all three prepared sponges, the PVFTX-100 sponge showed a high pore volume and large surface area, with a maximum percentage absorption capacity of 96%, 91%, 89.9%, 85.6%, and 80 for chlorobenzene, toluene, diesel, petrol, and hexane, respectively, after eightcycles. The organic solvent uptake using PVFTX-100, PVFSDS, and PVFT-80 sponges is quite a unique and simple technology, which could be employed at a large scale for contaminated soil/water systems.

Synthesis of Graphene-Based Nanocomposites for Environmental Remediation Applications: A Review.

The term graphene was coined using the prefix "graph" taken from graphite and the suffix "-ene" for the C=C bond, by Boehm et al. in 1986. The synthesis of graphene can be done using various methods. The synthesized graphene was further oxidized to graphene oxide (GO) using different methods, to enhance its multitude of applications. Graphene oxide (GO) is the oxidized analogy of graphene, familiar as the only intermediate or precursor for obtaining the latter at a large scale. Graphene oxide has recently obtained enormous popularity in the energy, environment, sensor, and biomedical fields and has been handsomely exploited for water purification membranes. GO is a unique class of mechanically robust, ultrathin, high flux, high-selectivity, and fouling-resistant separation membranes that provide opportunities to advance water desalination technologies. The facile synthesis of GO membranes opens the doors for ideal next-generation membranes as cost-effective and sustainable alternative to long existing thin-film composite membranes for water purification applications. Many types of GO-metal oxide nanocomposites have been used to eradicate the problem of metal ions, halomethanes, other organic pollutants, and different colors from water bodies, making water fit for further use. Furthermore, to enhance the applications of GO/metal oxide nanocomposites, they were deposited on polymeric membranes for water purification due to their relatively low-cost, clear pore-forming mechanism and higher flexibility compared to inorganic membranes. Along with other applications, using these nanocomposites in the preparation of membranes not only resulted in excellent fouling resistance but also could be a possible solution to overcome the trade-off between water permeability and solute selectivity. Hence, a GO/metal oxide nanocomposite could improve overall performance, including antibacterial properties, strength, roughness, pore size, and the surface hydrophilicity of the membrane. In this review, we highlight the structure and synthesis of graphene, as well as graphene oxide, and its decoration with a polymeric membrane for further applications.

Modified low-temperature synthesis of graphene oxide nanosheets: Enhanced adsorption, antibacterial and antioxidant properties.

Herein, we report a simple, low-temperature, ecofriendly synthesis of graphene oxide nanosheets (GONs). Graphite powder was treated with KMnO4 and a concentrated H2SO4/H3PO4 mixture to synthesize GONs. The effects of various reaction conditions such as reaction time, temperature, amounts of cleaving agents (H2SO4/H3PO4), and oxidant (KMnO4) were investigated. The synthesized GONs were examined by various techniques in order to investigate their characteristics. The best results of the synthesized GONs were observed at 35 °C within 10 h of reaction time having 8:2 ratios of H2SO4/H3PO4 acid mixture. The main absorption peak in the UV-vis spectra of GONs was at 258 nm, which is due to the π-π* transition of the atomic CC bonds. The existence of stretching vibrations of C꞊O, O-H, C-H, and C-O in the Fourier transform infrared (FTIR) spectra verified the formation of GONs. Presence of a sharp peak at 2θ = 10° with an interlayer spacing distance of 0.88 nm in the observed XRD pattern revealed that the synthesized GONs were totally oxidized and that the interlayer spacing increased. The morphological investigations confirmed the formation of ultrathin, transparent, curly, and homogenous GONs. The synthesized GONs were applied as an adsorbent for the rapid uptake of four different pesticides viz.; Profenofos, Ethion, Cypermethrin, Thiamethoxam (TMX) from the pesticides spiked water samples. About 86% adsorption of Profenofos + Cypermethrin, and 50% adsorption of ethion and thiamethoxam took place within 20 min in presence of 10 mg GONs. In addition to this, the prepared GONs were tested for the antibacterial activity against four bacterial strains by agar well diffusion method. The synthesized GONs provide a significant inhibition for gram -positive (Bacillus subtilis, and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. Moreover, the radical scavenging activities (RSA) of GONs were also checked and compared with Gallic acid as a standard. The obtained RSA of GONs was 60% in comparison to the 80% as of the standard Gallic acid at 1000 µg/mL concentration.