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In this study, granulated activated charcoal (GAC) and bio charcoal (BC) is used as a filler in P3 biosand bag filter to study their filtration performance against a range of fluoride impurities from 1–1400 mg/L. A set of experiments are done to analyze the filtration efficiency of the sandbag filter against fluoride impurities after incorporating different amounts (e.g., 0.2, 2 kg) and a combination of GAC and BC. A combination of filler GAC and BC (1 kg each) have exhibited excellent results with 100% fluoride removal efficiency against 5 mg/L fluoride impurities for an entire experimental time of 165 min. It is because of the synergetic effect of adsorption caused by the high surface area (739 m2/g) of GAC and hydroxyapatite groups in BC. The data from remediation experiments using individual GAC and BC are fitted into the Langmuir and Freundlich Isotherm Models to check their adsorption mechanism and determine GAC and BC’s maximum adsorption capacity (Qm). The remediation data for both GAC and BC have shown the better fitting to the Langmuir Isotherm Model with a high R2 value of 0.994 and 0.970, respectively, showing the excellent conformity with monolayer adsorption. While the GAC and BC have presented negative Kf values of −1.08 and −0.72, respectively, for Freundlich Model, showing the non-conformity to multilayer adsorption. The Qm values obtained from Langmuir Model for GAC is 6.23 mg/g, and for BC, it is 9.13 mg/g. The pH study on adsorption efficiency of individual GAC and BC against 5 mg/L of fluoride impurities indicates the decrease in removal efficiency with an increase in pH from 3 to 9. For example, BC has shown removal efficiency of 99.8% at pH 3 and 99.5% at pH 9, while GAC has exhibited removal efficiency of 96.1% at pH 3 and 95.9% at pH 9. Importantly, this study presents the significance of the synergetic application of GAC and BC in the filters, where GAC and BC are different in their origin, functionalities, and surface characteristics.

Understanding the morphology and flow behavior of cellulose nanofibers (CNFs) dispersed in organic solvents can improve the process of fabricating new cellulose-based nanocomposites. In this study,...

Two different chemical methods, TEMPO-oxidation and nitro-oxidation, were used to extract carboxyl cellulose nanofibers (CNFs) from non-wood biomass sources (i.e., jute, soft and hard spinifex grasses). The combined TEMPO-oxidation and homogenization approach was very efficient to produce CNFs from the cellulose component of biomass; however, the nitro-oxidation method was also found to be effective to extract CNFs directly from raw biomass even without mechanical treatment. The effect of these two methods on the resulting cross-section dimensions of CNFs was investigated by solution small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The UV-Vis spectroscopic data from 0.1 wt% TEMPO-oxidized nanofiber (TOCNF) and nitro-oxidized nanofiber (NOCNF) suspensions showed that TOCNF had the highest transparency (> 95%) because of better dispersion, resulted from the highest carboxylate content (1.2 mmol/g). The consistent scattering and microscopic results indicated that TOCNFs from jute and spinifex grasses possessed rectangular cross-sections, while NOCNFs exhibited near square cross-sections. This study revealed that different oxidation methods can result in different degrees of biomass exfoliation and different CNF morphology.

Green and sustainable cellulose nanocrystals-TiO2 nanocomposite was prepared for environmental applications using a facile method comprised of thermal degradation of aqueous titanium precursors., Nanocellulose, which can be derived from any cellulosic biomass, has emerged as an appealing nanoscale scaffold to develop inorganic–organic nanocomposites for a wide range of applications. In this study, titanium dioxide (TiO2) nanocrystals were synthesized in the cellulose nanocrystal (CNC) scaffold using a simple approach, i.e., hydrolysis of a titanium oxysulfate precursor in a CNC suspension at low temperature. The resulting TiO2 nanoparticles exhibited a narrow size range between 3 and 5 nm, uniformly distributed on and strongly adhered to the CNC surface. The structure of the resulting nanocomposite was evaluated by transmission electron microscopy (TEM) and X-ray diffraction (XRD) methods. The growth mechanism of TiO2 nanocrystals in the CNC scaffold was also investigated by solution small-angle X-ray scattering (SAXS), where the results suggested the mineralization process could be described by the Lifshitz–Slyozov–Wagner theory for Ostwald ripening. The demonstrated TiO2/CNC nanocomposite system exhibited excellent performance in dye degradation and antibacterial activity, suitable for a wide range of environmental remediation applications.

Proton exchange membranes (PEMs), such as Nafion, are still one of the reasons for the high cost of PEMFCs. Among the alternatives, cellulose, a low cost and biodegradable material, has been considered in the form of its derivatives, such as cellulose acetate, bacterial cellulose or nanocellulose, as the PEM in fuel cells. However, its use involves more chemical synthesis steps. Here, we use low-cost 1.5-micron cellulose filter paper as the scaffold and prepare membranes for PEMFCs by simply impregnating it with a 10% Nafion solution or immersing it in resorcinol bis(diphenyl phosphate) (RDP). The prepared membranes are primarily composed of cellulose, with a cellulose to Nafion or RDP ratio of 2 : 1 or 1 : 1. The membrane electrode assemblies (MEAs) incorporating the as-prepared membranes exhibit a maximum output power of 23 mW cm−2 at 80 °C for the cellulose/Nafion membrane or 10 mW cm−2 at 60 °C for the cellulose/RDP membrane with only 0.1 mg cm−2 Pt loading on the anode and cathode, when operated in air. The stability results of the membranes after 100 hours of continuous operation indicate a loss of only 10% in power for the cellulose/Nafion membrane and 20% for the cellulose/RDP membrane. It is revealed by FTIR spectroscopy that both the Nafion polymer and RDP were hydrogen bonded to the cellulose fibers, facilitating proton conduction and stabilizing them against further dissolution.

Synthetic rubber produced from nonrenewable fossil fuel requires high energy costs and is dependent on the presumed unstable petroleum price. Natural rubber latex (NRL) is one of the major alternative sustainable rubber sources since it is derived from the plant &lsquo, Hevea brasiliensis&rsquo, Our study focuses on integrating sustainably processed carboxycellulose nanofibers from untreated jute biomass into NRL to enhance the mechanical strength of the material for various applications. The carboxycellulose nanofibers (NOCNF) having carboxyl content of 0.94 mmol/g was prepared and integrated into its nonionic form (&ndash, COONa) for its higher dispersion in water to increase the interfacial interaction between NRL and NOCNF. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analyses of NOCNF showed the average dimensions of nanofibers were length (L) = 524 &plusmn, 203 nm, diameter (D) 7 &plusmn, 2 nm and thickness 2.9 nm. Furthermore, fourier transform infra-red spectrometry (FTIR) analysis of NOCNF depicted the presence of carboxyl group. However, the dynamic light scattering (DLS) measurement of NRL demonstrated an effective diameter in the range of 643 nm with polydispersity of 0.005. Tensile mechanical strengths were tested to observe the enhancement effects at various concentrations of NOCNF in the NRL. Mechanical properties of NRL/NOCNF films were determined by tensile testing, where the results showed an increasing trend of enhancement. With the increasing NOCNF concentration, the film modulus was found to increase quite substantially, but the elongation-to-break ratio decreased drastically. The presence of NOCNF changed the NRL film from elastic to brittle. However, at the NOCNF overlap concentration (0.2 wt. %), the film modulus seemed to be the highest.

High aspect ratio carboxycellulose nanofibers (NOCNF), having typical length over 1000 nm, width ∼4.6 nm, thickness ∼1.3 nm, and carboxylate content of 0.42 mmol/g, were extracted from jute fibers using a modified nitro-oxidation method. The extracted nanofiber was found to possess crystallinity of 69% (measured by wide-angle X-ray diffraction, WAXD), relatively higher than that of raw jute fibers (crystallinity ∼61%). Gelation of NOCNF in aqueous suspensions was observed due to the high aspect ratio of the fiber even at a relatively low concentration. Rheological studies on the NOCNF suspensions at different concentrations (0.01–1 wt %) revealed the shear-thinning behavior with increasing shear rate. The corresponding viscoelastic moduli (G′ and G′′) results indicated that the NOCNF suspension at concentration between 0.1 and 0.2 wt % possessed a liquid–gel transition. The rheological data near the gelation point could be fitted by the Winter–Chambon model, where the results confirmed the formation of a ...

Mechanistic behavior and flow properties of cellulose nanofibers (CNFs) in aqueous systems can be described by the crowding factor and the concept of contact points, which are functions of the aspect ratio and concentration of CNF in the suspension. In this study, CNFs with a range of aspect ratio and surface charge density (380–1360 μmol/g) were used to demonstrate this methodology. It was shown that the critical networking point of the CNF suspension, determined by rheological measurements, was consistent with the gel crowding factor, which was 16. Correlated to the crowding factor, both viscosity and modulus of the systems were found to decrease by increasing the charge density of CNF, which also affected the flocculation behavior. Interestingly, an anomalous rheological behavior was observed near the overlap concentration (0.05 wt %) of CNF, at which the crowding factor was below the gel crowding factor, and the storage modulus (G′) decreased dramatically at a given frequency threshold. This behavior ...

Carboxylated cellulose nanofibers (CNFs), having an average width of 7 nm and thickness of 1.5 nm, were produced by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation method. The fiber cross-sectional dimensions were determined using small-angle X-ray scattering (SAXS), transmission electron microscopy and atomic force microscopy techniques, where the rheological properties under different concentration and ionic strength were also investigated. The formation of hydrogel was evidenced by increasing the CNF concentration or ionic strength of the solvent (water), while the gel structure in ion-induced CNF hydrogels was found to be relatively inhomogeneous. The gelation behavior was closely related to the segmental aggregation of charged CNF, which could be quantitatively characterized by the correlation length (ξ) from the low-angle scattering profile and the scattering invariant (Q) in SAXS.

In this paper, we report the simple synthesis, detailed characterization, and total wastewater cleanup by adsorption using bare and surfactant-functionalized cerium oxide (CeO2) nanoparticles. The synthesis of CeO2 nanoparticles was performed by a facile aqueous solution process and characterized by a diverse range of techniques, which confirmed that the nanoparticles are well-crystalline, possessing good structural and optical properties. The competence of the prepared nanoparticles was further explored to determine the dye removal efficiency. The developed nanoparticles have also provided chlorine-free disinfection of water. The observed results revealed that the synthesized nanoparticles efficiently lower the pollutant concentrations, reduced turbidity, and exhibited significant reductions in total dissolved solids, chemical and biochemical oxygen demands, and pathogenic load. Interestingly, the surfactant-functionalized nanoparticles revealed that they possess the ability to remove approximately 99% o...

Proton-exchange membrane fuel cells (PEMFCs) are considered to be one of the most promising clean technologies to mitigate climate change, air pollution, and energy crisis. Although PEMFCs have been intensively investigated over the past five decades, the relatively low current density, high cost, and poor durability remain as obstacles to full commercialization. In this study, we present the development and the application of a porosity-tunable carbon aerogel (CA) as an alternative to the carbon support in the PEMFC to overcome its technical barriers. CA demonstrates highly tunable mesopore volume and surface area. The N2 isotherm with non-localized density functional theory analysis shows the optimized CA had extremely high mesopore volume, which was 4.26 times larger than the traditional carbon support (i.e., Vulcan XC-72R). Transmission electron microscopy shows a better catalyst (i.e., platinum nanoparticles) distribution on the CA support. This even distribution of platinum nanoparticles significantly enhances the catalyst utilization of the electrodes in our cyclic voltammetry analysis. It also contributes up to a 713% higher specific power density in our fuel cell testing. The standard accelerated stress tests exhibit that CA has excellent durability compared with the conventional carbon support. Thus, the mesoporous CA provides an efficient and durable alternative to existing carbon material as a catalyst support in PEMFCs.

Membrane technology remains the most energy-efficient process for removing contaminants (micrometer-size particles to angstrom-size hydrated ions) from water. However, the current membrane technolo ...

A simple approach was developed to prepare carboxycellulose nanofibers directly from untreated biomass using nitric acid or nitric acid-sodium nitrite mixtures. Experiments indicated that this approach greatly reduced the need for multichemicals, and offered significant benefits in lowering the consumption of water and electric energy, when compared with conventional multiple-step processes at bench scale (e.g., TEMPO oxidation). Additionally, the effluent produced by this approach could be efficaciously neutralized using base to produce nitrogen-rich salts as fertilizers. TEM measurements of resulting nanofibers from different biomasses, possessed dimensions in the range of 190–370 and 4–5 nm, having PDI = 0.29–0.38. These nanofibers exhibited lower crystallinity than untreated jute fibers as determined by TEM diffraction, WAXD and 13C CPMAS NMR (e.g., WAXD crystallinity index was ∼35% for nanofibers vs 62% for jute). Nanofibers with low crystallinity were found to be effective for removal of heavy metal...

Agricultural residues derived cellulose was used to synthesize a new series of carboxy functionalized cellulosic nanoparticles (quasi-spherical shaped, 13.2–21.5% carboxyl content) and macro-sized 6-carboxycelluloses (long-fibril shaped, 1.7–22% carboxyl content). The DP (50–70) and yield (upto 46%) of nanoparticles were manipulated by controlling the reaction temperature and time. TGA/DTG thermographs of the carboxycelluloses gave thermostability data and co-related well with the residual crystalline, amorphous, and anhydroglucuronic acid content. The particle shape and size had no effect on the thermal stability. Some derivatives were fully or partially soluble in aqueous alkali and non-aqueous solvents, which can lead to increased versatility of these polymers.

Agricultural residue derived cellulose and cotton cellulose were used to synthesize quasi-spherical nanoparticles of 6-carboxycellulose having diameter 25-35 nm. This provides a new range of functionalized nanostructured celluloses with increased versatility and applications. The nanoparticles were efficient in stabilizing carbon nanotube dispersions and were effective anti-microbial agents against E. coli.