Superhydrophilic graphene oxide/electrospun cellulose nanofibre for efficient adsorption of organophosphorus pesticides from environmental samples

On the versatility of graphene-cellulose composites: An overview and bibliometric assessment

Practical benefits of graphene-cellulose composites (GCC) are categorical. Diverse salient features like thermal and electrical conductivity, mechanical strength, and durability make GCC advantageous for widespread applications. Despite extensive studies the basic understanding of various fundamental aspects of this novel complex remains deficient. Based on this fact, a critical overview and bibliometric analysis involving the overall prospects of GCC was made wherein a total of 1245 research articles from the Scopus database published during the year 2002 to 2020 were used. For the bibliometric assessment, various criteria including the publication outputs, co-authorships, affiliated countries, and co-occurrences of the authors' keywords were explored. Environmental amiability, sustainability, economy, and energy efficiency of GCC were emphasized. In addition, the recent trends, upcoming challenges, and applied interests of GCC were highlighted. The findings revealed that the studies on GCC related to the energy storage, adsorption, sensing, and printing are ever-increasing, indicating the global research drifts on GCC. The bibliometric map analysis displayed that among the researchers from 61 countries/territories, China alone contributed about 50 % of the international publications. It is asserted that the current article may offer taxonomy to navigate into the field of GCC wherein stronger collaboration networks can be established worldwide through integrated research activities desirable for sustainable development.

Synthesis and Characterization of Environmentally Friendly β-Cyclodextrin Cross-Linked Cellulose/Poly(vinyl alcohol) Hydrogels for Adsorption of Malathion

The widespread use of malathion enhances agricultural plant productivity by eliminating pests, weeds, and diseases, but it may lead to serious environmental pollution and potential health risks for humans and animals. To mitigate these issues, environmentally friendly hydrogel adsorbents for malathion were synthesized using biodegradable polymers, specifically cellulose, β-cyclodextrin (β-CD), poly(vinyl alcohol) (PVA), and biobased epichlorohydrin as a cross-linker. This study investigated the effects of the cellulose-to-PVA ratio and epichlorohydrin (ECH) content on the properties and malathion adsorption capabilities of β-CD/cellulose/PVA hydrogels. It was found that the gel content of the hydrogels increased with a higher cellulose-to PVA and ECH ratio, whereas the swelling ratio decreased, indicating a denser structure that impedes water permeation. In addition, various parameters affecting the malathion adsorption capacity of the hydrogel, namely, contact time, pH, hydrogel dosage, initial concentration of malathion, and temperature, were studied. The hydrogel prepared with a β-CD/cellulose/PVA ratio of 20:40:40 and 9 mL of ECH exhibited the highest malathion adsorption rate and capacity, which indicated an equilibrium adsorption capacity of 656.41 mg g-1 at an initial malathion concentration of 1000 mg L-1. Fourier transform infrared spectroscopy (FTIR), ζ-potential, and X-ray photoelectron spectroscopy (XPS) and NMR spectroscopy confirmed malathion adsorption within the hydrogel. The adsorption process followed intraparticle diffusion kinetics and corresponded to Freundlich isotherms, indicating multilayer adsorption on heterogeneous substrates within the adsorbent, facilitated by diffusion.

Recent advances in nanocellulose-based two-dimensional nanostructured membranes for sustainable water purification: A review

Nanocellulose (NC), a one-dimensional nanomaterial, is considered a sustainable material for water and wastewater purification because of its promising hydrophilic surface and mechanical characteristics. In this regard, nanostructured membranes comprising NC and two-dimensional (2D) nanomaterials emerged as advanced membranes for efficient and sustainable water purification. This article critically reviews the recent progress on NC-2D nanostructured membranes for water and wastewater treatment. The review highlights the main techniques employed to fabricate NC-2D nanostructured membranes. The physicochemical properties, including hydrophilicity, percent porosity, surface roughness, structure, and mechanical and thermal stability, are summarized. The key performance indicators such as permeability, rejection, long operation stability, antifouling, and interaction mechanisms are thoroughly discussed to evaluate the role of NC and 2D nanomaterials. Finally, summary points and future development work are highlighted to overcome the challenges for potential practical applications. This review contributes to the design and development of advanced membranes to solve growing water pollution concerns in a sustainable manner.

Advances in metal-organic frameworks for water remediation applications

Rapid industrialization and agricultural development have resulted in the accumulation of a variety of harmful contaminants in water resources. Thus, various approaches such as adsorption, photocatalytic degradation and methods for sensing water contaminants have been developed to solve the problem of water pollution. Metal-organic frameworks (MOFs) are a class of coordination networks comprising organic-inorganic hybrid porous materials having organic ligands attached to inorganic metal ions/clusters via coordination bonds. MOFs represent an emerging class of materials for application in water remediation owing to their versatile structural and chemical characteristics, such as well-ordered porous structures, large specific surface area, structural diversity, and tunable sites. The present review is focused on recent advances in various MOFs for application in water remediation via the adsorption and photocatalytic degradation of water contaminants. The sensing of water pollutants using MOFs via different approaches, such as luminescence, electrochemical, colorimetric, and surface-enhanced Raman spectroscopic techniques, is also discussed. The high porosity and chemical tunability of MOFs are the main driving forces for their widespread applications, which have huge potential for their commercial use.

Advances in electrospun materials for the adsorption and separation of environmental pollutants: A comprehensive review

Despite a broad range of new techniques developed, adsorption methods remain one of the technologies of choice for the removal of contaminants. However, significant progress has also been made in these, which finds reflection in a new spectrum of adsorbents that can be used. This comprehensive review discusses properties, advantages, and perspectives on the use of custom-made electrospun adsorbents in the processes of heavy metals, agrochemicals, and microplastic contaminants removal from the environment. It presents the versatility and adaptability of materials that can be used as electrospun fibers matrix, also considering the mechanism and parameters of the sorption process carried out with them. The presented review proves, that due to the use of new, custom-made sorbents, such as electrospun materials, the adsorption processes still possess great application potential and development opportunities to provide an attractive and effective alternative to other remediation techniques.

Nano/micro-cellulose-based materials as remarkable sorbents for the remediation of agricultural resources from chemical pollutants

Overusing pesticides, fertilizers, and synthetic dyes has significantly increased their presence in various parts of the environment. The transportation of these pollutants into agricultural soil and water through rivers, soils, and groundwater has seriously threatened human and ecosystem health. Applying techniques and materials to clean up agricultural sources from pesticides, heavy metals (HMs), and synthetic dyes (SDs) is one of the major challenges in this century. The sorption technique offers a viable solution to remediate these chemical pollutants (CHPs). Cellulose-based materials have become popular in nano and micro scales because they are widely available, safe to use, biodegradable, and have a significant ability to absorb substances. Nanoscale cellulose-based materials exhibit greater capacity in absorbing pollutants compared to their microscale counterparts because they possess a larger surface area. Many available hydroxyl groups (-OH) and chemical and physical modifications enable the incorporation of CHPs on to cellulose-based materials. Following this potential, this review aims to comprehensively summarize recent advancements in the field of nano- and micro-cellulose-based materials as effective adsorbents for CHPs, given the abundance of cellulosic waste materials from agricultural residues. The recent developments pertaining to the enhancement of the sorption capacity of cellulose-based materials against pesticides, HMs, and SDs, are deliberated.

Encapsulation of Copper Nanoparticles in Electrospun Nanofibers for Sustainable Removal of Pesticides

The excellent catalytic properties of copper nanoparticles (CuNPs) for the degradation of the highly toxic and recalcitrant chlorpyrifos pesticide are widely known. However, CuNPs generally present low stability caused by their high sensitivity to oxidation, which leads to a change of the catalytic response over time. In the current work, the immobilization of CuNPs into a polycaprolactone (PCL) matrix via electrospinning was demonstrated to be a very effective method to retard air and solvent oxidation and to ensure constant catalytic activity in the long term. CuNPs were successfully anchored into PCL electrospun fibers in the form of Cu₂O at different concentrations (from 1.25 wt % to 5 wt % with respect to the PCL), with no signs of loss by leaching out. The PCL mats loaded with 2.5 wt % Cu (PCL-2.5Cu) almost halved the initial concentration of pesticide (40 mg/L) after 96 h. This process was performed in two unprompted and continuous steps that consisted of adsorption, followed by degradation. Interestingly, the degradation process was independent of the light conditions (i.e., not photocatalytic), expanding the application environments (e.g., groundwaters). Moreover, the PCL-2.5Cu composite presents high reusability, retaining the high elimination capability for at least five cycles and eliminating a total of 100 mg/L of chlorpyrifos, without exhibiting any sign of morphological damages.

Polymeric membranes functionalized with nanomaterials (MP@NMs): A review of advances in pesticide removal

The excessive contamination of drinking water sources by pesticides has a pernicious impact on human health and the environment since only 0.1% of pesticides is utilized effectively to control the and the rest is deposited in the environment. Filtration by polymeric membranes has become a promising technique to deal with this problem; however, the scientific community, in the need to find better pesticide retention results, has begun to meddle in the functionalization of polymeric membranes. Given the great variety of membrane, polymer, and nanomaterial synthesis methods present in the market, the possibilities of obtaining membranes that adjust to different variables and characteristics related to a certain pesticide are relatively extensive, so it is expected that this technology will represent one of the main pesticide removal strategies in the future. In this direction, this review focused on, - the main characteristics of the nanomaterials and their impact on pristine polymeric membranes; - the removal performance of functionalized membranes; and - the main mechanisms by which membranes can retain pesticides. Based on these insights, the functionalized polymeric membranes can be considered as a promising technology in the removal of pesticides since the removal performance of this technology against pesticide showed a significant increase. Obtaining membranes that adjust to different variables and characteristics related to a certain pesticide are relatively extensive, so it is expected that functionalized membrane technology will represent one of the main pesticide removal strategies in the future.

Insight into the adsorption properties of a β-cyclodextrin/phillipsite organophilic composite for effective removal of toxic organophosphorus pesticides: kinetic and advanced equilibrium studies

β-Cyclodextrin/phillipsite was used in the uptake of three pesticides from water achieving Qsat values of 360 mg g−1 (MPn), 321.6 mg g−1 (OM), and 434.5 mg g−1 (AC). The uptake energies suggested endothermic physisorption reactions.

Sustainable materials in the removal of pesticides from contaminated water: Perspective on macro to nanoscale cellulose

Recently, over utilization of pesticides in agrarian and non- agrarian sectors has resulted in a significant increment in the deposition of their remnants in different segments of the environmental media. The presence of pesticides and transportation of their different metabolites in rivers, ponds, lakes, soils, air, groundwater sources and drinkable water sources has demonstrated a high threat to human wellbeing and the climate. Thus, the removal of pesticides and their metabolites from contaminated water is imperative to lessen the ill effects of pesticides on human beings. In the present article, we have appraised recent advances in pesticides removal utilizing low cost pristine and functionalized cellulose biomass-based derivatives. One of the key focus has been on better understand the destiny of pesticides in the environment as well as their behaviour in the water. In addition, the impact of magnetite cellulose nanocomposites, cellulose derived photo nano-catalyst, cellulose/clay nano composites, CdS/cellulose nanocomposites and activated carbons/biochar on percent removal of pesticides have also been a part of the current review. The impact of different parameters such as adsorbent dosage, pH, time of contact and initials pesticide concentration on adsorption capacity and adsorption kinetics followed during absorption by different cellulosic bio-adsorbents has also been given. The cellulosic biomass is highly efficient in the removal of pesticides and their efficiency further increases upon functionalization or their conversion into activated carbons forms. Nano particles loaded cellulosic materials have in general found to be less efficient than raw, functionalized cellulosic materials and activated carbons. Further, among different nano particles loaded with cellulose-based materials, cellulose/MnO₂ photonanocatalyst were noticed to be more effective. So considerable efforts should be given to determine the finest practices that relate to the dissipation of different pesticides from the water.

Graphene oxide loaded fibrous matrixes of polyether block amide (PEBA) elastomer as an adsorbent for removal of cationic dye from wastewater

Novel highly porous nanoparticle materials are increasingly being applied in adsorption processes, but they need to be supported by robust matrixes to maintain their functionality. We present a study of hosting graphene oxide (GO) particles on polyether block amide (PEBA) melt electrospun fibers and applying such composite matrix to the adsorption of the cationic dye (crystal violet) from water. Various amounts of GO (from 0.5 to 2.0%) were mixed into pure PEBA and electrospun by melt electrospinning obtaining micro fibrous matrixes. These were characterized for morphology (SEM), chemical composition (FTIR), crystallinity (XRD), and wetting behavior (WCA). The increasing amount of GO adversely affected fiber diameter (reduced from 13.18 to 4.38 μm), while the hydrophilic properties (Water contact angle decrease from 109 to 76°) and overall dye adsorption was increased. Efficient adsorption has been demonstrated, reaching approximately 100 % removal efficiency using a 2% GO composite matrix at a dose of 40 mg/l and pH of 10. Further increase of GO concentration in polymer is not feasible due to instability in the electrospinning process.