Graphene has extraordinary properties for myriad applications in advanced technologies, underpinning breakthroughs in electronics, energy storage, catalysis, and composite materials. The increasing interests and commercial demands for graphene have resulted in the need for investigating its sustainable production. The conventional graphene production methods rely on fossil-derived precursors and energy-intensive processes, raising significant environmental and economic concerns as global demand accelerates. Various biomass-derived waste materials have been demonstrated as potential feedstocks for graphene production due to their abundant, renewable nature, offering a promising pathway toward sustainable production. This review critically examines the potential of biomass and biomass-derived waste as sustainable precursors for graphene production, with a particular focus on the often-overlooked coupling between precursor composition, synthesis pathway, and resulting graphene quality. While existing reviews predominantly treat precursor selection, synthesis methods, and sustainability metrics as independent variables, this work addresses a critical knowledge gap by integrating these dimensions into a unified materials-process-impact framework. Specifically, this framework establishes quantitative and conceptual links between (i) precursor chemistry and structure, (ii) process conditions and transformation mechanisms, and (iii) resulting graphene quality and environmental performance. By bridging these traditionally disconnected domains, the review enables a more systematic evaluation of trade-offs between graphene quality, scalability, and sustainability - an aspect that remains insufficiently addressed in current literature.

The never-ending increasing emissions of carbon dioxide (CO2) to the atmosphere is at an alarming rate, associated with many serious environmental concerns such as climate change and global warming. In order to mitigate the effects induced by CO2 emissions, many efforts have been dedicated to exploring practical strategies to reduce CO2 emissions. One of the strategies is to capture CO2 from point sources before its release to the atmosphere using adsorption technologies, commonly known as carbon capture and sequestration (CCS) technology. This review compares and discusses of currently available carbon-based materials as CO2 sorbents with the special focus on electrospun graphene carbon nanofibers and their functionalization, which possess excellent physicochemical properties with high specific surface area, wide pore size distribution, and high concentration of active adsorption sites for improving CO2 adsorption. Inclusively, this review will comprehensively focus on the development and modification of graphene electrospun carbon nanofibers (gCNFs) for optimizing CO2 capture.

In this review, the history of the graphene and their excellent structure and properties were briefly explained. The form of graphene in different allotropes and derivatives were also discussed as each type possessed different structures and properties, that were important in specific applications depending the quality of the produced graphene. On top of that, the main sustainability issues arise in the different synthesis methods for fabrication of graphene and graphene-based materials were discussed and reviewed. This review also focused in finding the cost-efficient, environmental-friendly, energy efficient, and low carbon footprint graphene precursors as an insight for potential development of sustainable graphene materials. Rice husk as an abundant and cheap lignocellulosic biomass wastes with high content of cellulose is a great candidate for sustainable graphene precursor. The excellent morphological structure, physicochemical, thermal, mechanical, and electrical properties of rice husks-derived graphene for utilization in wide-range of applications were discussed. This review also concluded on the future insights and perspectives of the rice husk-derived graphene.

Nanofibrous membranes for membrane distillation (MD) have demonstrated promising results in treating various water and wastewater streams. Significant progress has been made in recent decades because of the development of sophisticated membrane materials, such as superhydrophobic, omniphobic and Janus membranes. However, fouling and wetting remain crucial issues for long-term operation. This mini-review summarizes ideas as well as their limitations in understanding the fouling in membrane distillation, comprising organic, inorganic and biofouling. This review also provides progress in developing antifouling nanofibrous membranes for membrane distillation and ongoing modifications on nanofiber membranes for improved membrane distillation performance. Lastly, challenges and future ways to develop antifouling nanofiber membranes for MD application have been systematically elaborated. The present mini-review will interest scientists and engineers searching for the progress in MD development and its solutions to the MD fouling issues.

Electrospun nanofibers are emerging reinforcing fillers with epoxy matrix owing to its high aspect ratio, surface area, and mechanical properties resulting in wider applications. Application of non-woven configuration of nanofiber mats, collected from electrospinning has been traditionally confined to improve interlaminar responses of fiber reinforced composites. However, potential of short nanofiber in improving bulk matrix properties cannot be under estimated. This study adopts matrix modification approach by incorporating different concentration of nylon 6 short nanofiber in epoxy matrix to investigate its influence on tensile and viscoelastic properties of nanocomposite. Results showed a moderate improvement in modulus for nanocomposites despite to general drop in strength, however fracture energy and failure strain improved significantly at an optimum concentration of 0.1 wt% nanofiber. In addition, highest storage modulus as well as damping factor was recorded with decline in glass transition temperature for 0.1 wt% nanofiber content. Moreover, it was revealed that addition of nanofiber altered brittle fracture to neck-featured ductile mode and effectively introduced energy absorbing interfaces making it well suit for diverse applications.

This study presents the fabrication of polyethyleneimine (PEI)–graphene-derived rice husk char (GRHC)/activated carbon nanofiber (ACNF) composites via electrospinning and physical activation processes and its adsorption performance toward CO2. This study was performed by varying several parameters, including the loading of graphene, impregnated and nonimpregnated with amine, and tested on different adsorption pressures and temperatures. The resultant ACNF composite with 1% of GRHC shows smaller average fiber diameter (238 ± 79.97 nm) with specific surface area (S BET) of 597 m2/g, and V micro of 0.2606 cm3/g, superior to pristine ACNFs (202 m2/g and 0.0976 cm3/g, respectively). ACNF/GRHC0.01 exhibited CO2 uptakes of 142 cm3/g at atmospheric pressure and 25°C, significantly higher than that of pristine ACNF’s 69 cm3/g. The GRHC/ACNF0.01 was then impregnated with PEI and further achieved impressive increment in CO2 uptake to 191 cm3/g. Notably, the adsorption performance of CO2 is directly proportional to the pressure increment; however, it is inversely proportional with the increased temperature. Interestingly, both amine-impregnated and nonimpregnated GRHC/ACNFs fitted the pseudo first-order kinetic model (physisorption) at 1 bar; however, best fitted the pseudo second-order kinetic model (chemisorption) at 15 bar. Both GRHC/ACNF and PEI-GRHC/ACNF samples obeyed the Langmuir adsorption isotherm model, which indicates monolayer adsorption. At the end of this study, PEI-GRHC/ACNFs with excellent CO2 adsorption performance were successfully fabricated.

Hybrid polymer composites reinforced with synthetic and natural fibers are gaining more interest in current composite technology in an effort to promote sustainability without sacrificing the performance of synthetic fiber reinforced polymer composites. The goal of this study is to see how the fiber stacking sequence of carbon and ramie fiber, as well as the orientation of ramie fiber, affects the quasi-static indentation behaviour of carbon/ramie fiber reinforced epoxy hybrid composites. The hybrid composite specimens were made using a hand layup approach followed by a hot pressing process. The quasi-static indentation properties of carbon/ramie fiber reinforcements in epoxy matrix were investigated using a hemispherical indenter at varying indenter displacement rates of 10, 20, and 30 ​mm/min for the stated stacking sequence and orientation. The indentation resistance qualities of carbon/ramie fiber reinforced epoxy hybrid composites were evaluated in terms of indentation force, hybrid composite specimen energy absorption capability, and hybrid composite specimen damage caused by hemispherical indenter penetration. The results reveal that a carbon/ramie fiber reinforced epoxy hybrid composite with 5 ramie fiber layers has better energy absorption capabilities, absorbing 114.926 ​J at a 20 ​mm/min indentation rate. Similarly, the indentation force in hybrid composites increases as the number of carbon/ramie fiber layers increases. These results indicate that carbon/ramie fiber reinforced epoxy hybrid composites have a great potential towards low velocity impact applications.

Activated carbon nanofibers (ACNFs) incorporated with four different types of metal oxides; magnesium oxide (MgO), manganese dioxide (MnO2), zinc oxide (ZnO), and calcium oxide (CaO) were successfully prepared via a simple electrospinning and pyrolysis process. Optimum electrospinning and pyrolysis parameters were performed to obtain porous ACNFs composites for CO2 capture. The porous and textural characteristics of the resultant ACNFs composites were performed using N-2 adsorption isotherms at 77 K, while the features and morphologies were observed using TEM and FE-SEM. The EDX and Raman analysis were used to determine and analyse the elemental composition in the ACNFs. It was observed that ACNFs incorporated MgO (ACNF2) exhibited the largest surface area (413 m(2)/g) and the highest micropore volume (0.1777 cm(3)/g) as compared to pristine ACNF (ACNF1) and other ACNFs composites. ACNF2 also possessed the smallest fiber diameter of 357.8 +/- 16.7 nm as compared to other samples. The successful incorporation of all metal oxides in electrospun fibers were proven by EDX analysis. All resultant ACNFs exhibited D- and G-peaks in Raman spectra indicating the carbon-based materials structure. As expected, the ACNF2 attained the highest CO2 adsorption of 60 cm(3)/g at 298 K as compared to other ACNFs samples which is correspond to N-2 adsorption capacity. The CO2 adsorption/desorption isotherms of the best composite sample (ACNF2) was measured at three different temperatures (273, 298, and 318 K) at 1 bar through a volumetric adsorption process and this result was compared to ACNF1. It shown that the CO2 adsorption capacity is inversely proportional to the increasing temperature in which as the adsorption temperature increased, the adsorbed amounts of CO2 decreased. These results indicated that the incorporation of MgO into ACNFs shows the best improvement in their physicochemical properties for enhanced adsorption performance of CO2 under practical conditions.

The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 °C, 200 °C, 300 °C, and 400 °C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 °C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 °C (1556.3 m2/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7° indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm3/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

In this work, we report the preparation of polyacrylonitrile (PAN)-based activated carbon nanofibers composited with different concentrations of reduced graphene oxide (rGO/ACNF) (1%, 5%, and 10% relative to PAN weight) by a simple electrospinning method. The electrospun nanofibers (NFs) were carbonized and physically activated to obtain activated carbon nanofibers (ACNFs). Texture, surface and elemental properties of the pristine ACNFs and composites were characterized using various techniques. In comparison to pristine ACNF, the incorporation of rGO led to changes in surface and textural characteristics such as specific surface area (SBET), total pore volume (Vtotal), and micropore volume (Vmicro) of 373 m2/g, 0.22 cm3/g, and 0.15 cm3/g, respectively, which is much higher than the pristine ACNFs (e.g., SBET = 139 m2/g). The structural and morphological properties of the pristine ACNFs and their composites were studied by Raman spectroscopy and X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) respectively. Carbon dioxide (CO2) adsorption on the pristine ACNFs and rGO/ACNF composites was evaluated at different pressures (5, 10, and 15 bars) based on static volumetric adsorption. At 15 bar, the composite with 10% of rGO (rGO/ACNF0.1) that had the highest SBET, Vtotal, and Vmicro, as confirmed with BET model, exhibited the highest CO2 uptake of 58 mmol/g. These results point out that both surface and texture have a strong influence on the performance of CO2 adsorption. Interestingly, at p < 10 bar, the adsorption process of CO2 was found to be quite well fitted by pseudo-second order model (i.e., the chemisorption), whilst at 15 bar, physisorption prevailed, which was explained by the pseudo-first order model.

A simple, promising, environmentally friendly, and high yield technique to synthesize high specific surface area (SSA) and porous graphene-like materials from glucose precursor through carbonization and controlled chemical iron chloride (FeCl3) activation was demonstrated. Designing this nanoporous graphene-based adsorbent with high SSA, abundant micropore volume, tunable pore size distribution, and high adsorption capacity, is crucial in order to deal with the demands of large-scale reversible natural gas storage applications. Raman spectroscopy, BET method of analysis, and N2 adsorption/desorption measurements at 196 °C were adopted to evaluate the structural and textural properties of the resultant glucose derived-graphene (gluGr) samples. The effects of different carbonization conditions, such as the inert environments (argon, helium, and argon) and temperatures (700, 800, 900, and 1,000 °C), have been studied. A glucose-derived graphene carbonized under nitrogen environment at 700 °C (NGr700) with highly interconnected network of micropores and mesopores and large SSA (767 m2/g) exhibited excellent methane (CH4) storage property with exceptionally high adsorption capacity, superior to other glucose-derived graphene (gluGr) samples. A maximum volumetric capacity up to 42.08 cm3/g was obtained from CH4 adsorption isotherm at 25 °C and 35 bar. Note that the adsorption performance of the CH4 is highly associated with the SSA and microporosity of the gluGr samples, especially NGr700 that was successfully synthesized by FeCl3 activation under N2 environment.

Herein this study, nanocomposite activated carbon nanofibers embedded with MnO2 (called as ACNFs/MnO2) were prepared by carbonization and activation of electrospun polyacrylonitrile (PAN) nanofibers for the removal of lead(II) ions from aqueous solution. The prepared ACNFs/MnO2 were characterized by their physicochemical properties and adsorptive behaviour towards lead(II) ions. SEM images showed that ACNFs/MnO2 possessed more compact structures with a smaller average fiber diameter (433.7 nm) as compared to ACNFs without MnO2 incorporation (called neat ACNFs hereafter with fiber diameter of 669.0 nm). EDX analysis revealed successful incorporation of MnO2 nanoparticles within the fibres. The specific surface area (SSA) of the ACNFs/MNO2 (599.4 m2/g) is higher than the SSA of neat ACNFs (478.2 m2/g). FTIR spectra of ACNF/MnO2 indicated the presence of MnO2 at peak 548 cm−1. Batch adsorption study showed that the optimum pH for maximum adsorption of lead(II) was at range 5.0 and isotherm study revealed that lead(II) adsorption on ACNFs/MnO is best fitted by Freundlich model with maximum adsorption of 120.3 mg/g. This nanocomposite carbonaceous material can be another promising sorbent material for heavy metals removal from water/wastewater.

Various types of activated carbon nanofibers' (ACNFs) composites have been extensively studied and reported recently due to their extraordinary properties and applications. This study reports the fabrication and assessments of ACNFs incorporated with graphene-based materials, known as gACNFs, via simple electrospinning and subsequent physical activation process. TGA analysis proved graphene-derived rice husk ashes (GRHA)/ACNFs possess twice the carbon yield and thermally stable properties compared to other samples. Raman spectra, XRD, and FTIR analyses explained the chemical structures in all resultant gACNFs samples. The SEM and EDX results revealed the average fiber diameters of the gACNFs, ranging from 250 to 400 nm, and the successful incorporation of both GRHA and reduced graphene oxide (rGO) into the ACNFs' structures. The results revealed that ACNFs incorporated with GRHA possesses the highest specific surface area (SSA), of 384 m2/g, with high micropore volume, of 0.1580 cm3/g, which is up to 88% of the total pore volume. The GRHA/ACNF was found to be a better adsorbent for CH4 compared to pristine ACNFs and reduced graphene oxide (rGO/ACNF) as it showed sorption up to 66.40 mmol/g at 25 °C and 12 bar. The sorption capacity of the GRHA/ACNF was impressively higher than earlier reported studies on ACNFs and ACNF composites. Interestingly, the CH4 adsorption of all ACNF samples obeyed the pseudo-second-order kinetic model at low pressure (4 bar), indicating the chemisorption behaviors. However, it obeyed the pseudo-first order at higher pressures (8 and 12 bar), indicating the physisorption behaviors. These results correspond to the textural properties that describe that the high adsorption capacity of CH4 at high pressure is mainly dependent upon the specific surface area (SSA), pore size distribution, and the suitable range of pore size.

In this work, activated carbon nanofibers (ACNFs) and graphene-derived rice husk (GRH)/ACNF composites (gACNFs) were straightforwardly fabricated through a simple electrospinning process and were consequently activated by using a physical method. The morphological, structural, and textural properties of the resultant ACNFs and (GRH)/ACNFs were characterized by scanning electron microscopy–energy dispersive x-ray spectroscopy, transmission electron microscopy, Raman spectra, thermal gravimetric analysis, and a N2 adsorption isotherm. From the results obtained, gACNFs exhibit better thermal stability properties than pristine ACNFs with improved carbon yield (up to 60%) as well as enhanced adsorption capacity (220 cm3/g). The results including a high specific surface area (592 m2/g) and availability of 80% micropore volumes have demonstrated that gACNFs exhibited double gas adsorption performance as compared to pristine ACNFs.

Activated-carbon nanofibers (ACNFs) provide a relatively new, modified structure of carbon-based adsorbents that have the ability to adsorb carbon dioxide due to their high specific surface area, wide distribution of porous structures, and high volume of active sites. In this study, cost-effective agricultural waste-based graphene synthesized from rice husk ashes was used as additive to enhance the ACNF properties. ACNF/graphene (gACNF) is still a relatively unexplored adsorbent. The resultant gACNF exhibited better thermal stability properties, with higher yield, larger specific surface area, and higher micropore volume. These properties are the main factors contributing to their enhanced adsorption performance towards CO2.

This book chapter gives a comprehensive review on the state-of-the-art development of nanofiber membranes as efficient adsorbent for removal of heavy metals in the waste water. The general introduction of heavy metals accumulation in waste water was first introduced, followed by alternatives method to remove heavy metals were discussed. Then, the concept and principles of electrospinning to produce electrospun nanofiber membranes with small fiber diameter and high specific surface area were thoroughly discussed, followed by surface modification on electrospun nanofibers to increase its effectiveness in removing heavy metals ions from the water. Lastly, future perspectives and challenges facing by electrospun nanofiber membranes for removal of heavy metals were later summarized.

In this work, activated carbon nanofibers (ACNFs) from precursor polyacrylnitrile (PAN) and manganese oxide (MnO2) were prepared via electrospinning process. The electrospun PAN/MnO2-based ACNFs were characterized in term of its morphological structure, functional group analysis and specific surface area using SEM-EDX, FTIR and BET analysis respectively. The comparative adsorption study of cadmium (II) ions from aqueous solution between the neat ACNFs, composite ACNFs and commercial granular activated carbon was also conducted. SEM analysis illustrated that composite ACNFs have more compact fibers with presence of MnO2 beads with smaller fiber diameter of 437.2 nm as compared to the neat ACNFs which is 575.5 nm. BET analysis elucidated specific surface area of ACNFs/MnO2 to be 67 m2/g. Under adsorption study, it was found out that Cd (II) removal by ACNFs/MnO2 was the highest (97%) followed by neat ACNFs (96%) and GAC (74%).

This study was performed primarily to investigate the effect of activated carbon nanofiber (ACNF) on carbon dioxide and methane separation performance of mixed matrix membrane (MMM). In this study, polysulfone (PSf)/ACNF mixed matrix membranes was fabricated using dry/wet inversion technique. The effect of PSf concentration and ACNF loading on the performance of mixed matrix membrane in terms of permeability and selectivity of CO2/CH4 gas separation was observed. The fabricated flat sheet mixed matrix membranes were characterized using Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analysis. From the SEM observations, it shows that sponge like structures images were observed upon the addition of ACNFs in the PSf/ACNF membranes was slowly decreased due to increasing weight percentage of ACNF. FT-IR result indicating the presence of carboxyl group in MMM at wavelength 1750 cm-1. Meanwhile, the MMMs were further tested to pure permeation test using pure CO2 and CH4 gas, the CO2 permeance improved and the selectivity of CO2/CH4 increased after the addition of ACNFs.

This study examines the methane adsorption capacity using graphene derived from glucose and ferric chloride (FeCl3). The graphene was prepared via simple method by dissolution of glucose and FeCl3 in water, vaporization of water in oven, and calcination process in quartz furnace. Graphene was successfully produced with impregnation ratio of glucose and FeCl3 at 1: 1 and calcination temperature of 650 degrees C. The prepared graphene subsequently underwent a volumetric adsorption setup, to measure the adsorption capacity of methane (CH4). The highest CH4 adsorption capacity obtained was 6.37 mmol/g at 3.5 bar and 298 K for 40 minutes. These result shows that the prepared graphene displayed good adsorption characteristic for CH4.