Search for: All records

The existence of organic pollutants in our environment is a growing concern. Many processes (e.g., textiles, painting, and printing) release waste effluents with organic pollutants (e.g., synthetic dyes) that harm aquatic systems. However, detecting and removing them efficiently and effectively is challenging. This study addressed this by developing a dual-functional plasmonic membrane using biowaste-derived nanocellulose for both detection and removal. The plasmonic nanomaterial was integrated with surface-enhanced Raman spectroscopy (SERS) to identify and quantify three organic pollutants (basic red 9, BR9; malachite green, MG; and methylene blue, MB). The nanocellulose removed these pollutants through electrostatic attraction. The organic pollutants were detected down to 0.05 mg/L, 0.25 mg/L, and 0.05 mg/L for BR9, MG, and MB, respectively; these concentrations are well below those considered to be environmentally hazardous. SERS analysis was performed in spiked streamwater samples to demonstrate detection in an environmentally relevant matrix. The nanomaterial was also used to remove the pollutants from aqueous matrices; removal efficiencies were 99.54 ± 0.16% for BR9, 99.50 ± 0.25% for MG, and 99.84 ± 0.10% for MB. For pollutant-spiked stream samples, removal efficiencies were 98.76 ± 1.26% for BR9, 97.50 ± 2.29% for MG, and 98.33 ± 1.59% for MB. This study demonstrates the high potential of this nanomaterial for the simultaneous detection and removal of organic contaminants, which provides the first example of using biowaste-derived functional nanomaterial for water testing and remediation concurrently. 

The increased demand for agricultural productivity to support the growing population has resulted in the expanded use of pesticides. However, modern pesticide applications contaminate air, water, soil, and unintentional target species. It is necessary to develop effective and sustainable methods to detect different pesticides within our environment. Surface-enhanced Raman spectroscopy (SERS) has garnered significant attention for its ability to detect and quantify environmental contaminants, as it is a rapid and sensitive technique that requires minimal sample preparation. The present study demonstrates the development of a biowaste-derived nanocellulose-based thin-film that, when integrated with gold nanoparticles, produces a sustainable and reproducible SERS nanosubstrate. In this study, three pesticides (carbaryl, ferbam, and thiabendazole) were sensitively and selectively detected by the combined use of this novel nanocellulose-based SERS nanosubstrate and a portable Raman instrument. The limits of detection were determined to be 1.34, 1.01, and 1.41 mg/L for carbaryl, ferbam, and thiabendazole, respectively, all of which are well below the agricultural application concentrations recommended. SERS signals were collected for both prepared ferbam spray solution and collected sprayed droplets, and it was found that there is no major difference in the signals, indicating that this detection method is reliable to detect pesticide droplets. A commercial pesticide was detectable by the biowaste-derived SERS nanosubstrate. This study is among the first to utilize biowaste-derived nanocellulose to create SERS nanosubstrate for pesticide detection in spray droplets. We demonstrate the high potential of biowaste-derived nanocellulose in combination with the portable Raman technique for agricultural pesticide spray detection. 

Anionic carboxylated cellulose nanofibers (CNF) are effective media to remove cationic contaminants from water. In this study, sustainable cationic CNF-based adsorbents capable of removing anionic contaminants were demonstrated using a simple approach. Specifically, the zero-waste nitro-oxidization process was used to produce carboxylated CNF (NOCNF), which was subsequently converted into a cationic scaffold by crosslinking with aluminum ions. The system, termed Al-CNF, is found to be effective for the removal of fluoride ions from water. Using the Langmuir isotherm model, the fluoride adsorption study indicates that Al-CNF has a maximum adsorption capacity of 43.3 mg/g, which is significantly higher than that of alumina-based adsorbents such as activated alumina (16.3 mg/g). The selectivity of fluoride adsorption in the presence of other anionic species (nitrate or sulfate) by Al-CNF at different pH values was also evaluated. The results indicate that Al-CNF can maintain a relatively high selectivity towards the adsorption of fluoride. Finally, the sequential applicability of using spent Al-CNF after the fluoride adsorption to further remove cationic contaminant such as Basic Red 2 dye was demonstrated. The low cost and relatively high adsorption capacity of Al-CNF make it suitable for practical applications in fluoride removal from water. 

In this study, a sulfonation approach using chlorosulfonic acid (CSA) to prepare cellulose sulfate nanofibers (CSNFs) from raw jute fibers is demonstrated. Both elemental sulfur content and zeta potential in the CSNFs are found to increase with increasing CSA content used. However, the corresponding crystallinity in the CSNFs decreases with the increasing amount of CSA used due to degradation of cellulose chains under harsh acidic conditions. The ammonium adsorption results from the CSNFs with varying degrees of sulfonation were analyzed using the Langmuir isotherm model, and the analysis showed a very high maximum ammonium adsorption capacity (41.1 mg/g) under neutral pH, comparable to the best value from a synthetic hydrogel in the literature. The high ammonium adsorption capacity of the CSNFs was found to be maintained in a broad acidic range (pH = 2.5 to 6.5). 

Thallium(I) (Tl(I)) pollution has become a pressing environmental issue due to its harmful effect on human health and aquatic life. Effective technology to remove Tl(I) ions from drinking water can offer immediate societal benefits especially in the developing countries. In this study, a bio-adsorbent system based on nitro-oxidized nanocellulose (NOCNF) extracted from sorghum stalks was shown to be a highly effective Tl(I) removal medium. The nitro-oxidation process (NOP) is an energy-efficient, zero-waste approach that can extract nanocellulose from any lignocellulosic feedstock, where the effluent can be neutralized directly into a fertilizer without the need for post-treatment. The demonstrated NOCNF adsorbent exhibited high Tl(I) removal efficiency (>90% at concentration < 500 ppm) and high maximum removal capacity (Qm = 1898 mg/g using the Langmuir model). The Tl(I) adsorption mechanism by NOCNF was investigated by thorough characterization of NOCNF-Tl floc samples using spectroscopic (FTIR), diffraction (WAXD), microscopic (SEM, TEM, and AFM) and zeta-potential techniques. The results indicate that adsorption occurs mainly due to electrostatic attraction between cationic Tl(I) ions and anionic carboxylate groups on NOCNF, where the adsorbed Tl(I) sites become nuclei for the growth of thallium oxide nanocrystals at high Tl(I) concentrations. The mineralization process enhances the Tl(I) removal efficiency, and the mechanism is consistent with the isotherm data analysis using the Freundlich model. 

The fuel cell is the best alternative to compensate for today's energy demand, but the high cost of fabrication of membranes ( e.g. , Nafion) hampers the widespread commercialization. Plant-derived nanocellulose is renewable, most abundant, and biocompatible with high strength and tunable surface chemistry. Here we have demonstrated the jute derived-nitro-oxidized carboxycellulose nanofibers (NOCNFs) as a viable and sustainable substitute for synthetic ionomer membranes used in proton exchange fuel cells (PEFCs). NOCNFs were obtained in two functionalities: carboxylate and carboxylic acid which were then transformed into nanopaper I and II, respectively. This is the first report where NOCNFs with two different functionalities were tested in PEFCs. The results indicated that nanopaper II performed better than nanopaper I with a high proton conductivity of 14.2 mS cm −1 and power density of 19.1 mW cm −2 at high temperature (80 °C) operation in PEFCs, along with excellent durability even for 24 h of operation. 

Raw wood was subjected to sequential oxidation to produce 2,3,6-tricarboxycellulose (TCC) nanofibers with a high surficial charge of 1.14 mmol/g in the form of carboxylate groups. Three oxidation steps, including nitro-oxidation, periodate, and sodium chlorite oxidation, were successfully applied to generate TCC nanofibers from raw wood. The morphology of extracted TCC nanofibers measured using TEM and AFM indicated the average length, width, and thickness were in the range of 750 ± 110, 4.5 ± 1.8, and 1.23 nm, respectively. Due to high negative surficial charges on TCC, it was studied for its absorption capabilities against Pb2+ ions. The remediation results indicated that a low concentration of TCC nanofibers (0.02 wt%) was able to remove a wide range of Pb2+ ion impurities from 5–250 ppm with an efficiency between 709–99%, whereby the maximum adsorption capacity (Qm) was 1569 mg/g with R2 0.69531 calculated from Langmuir fitting. It was observed that the high adsorption capacity of TCC nanofibers was due to the collective effect of adsorption and precipitation confirmed by the FTIR and SEM/EDS analysis. The high carboxylate content and fiber morphology of TCC has enabled it as an excellent substrate to remove Pb2+ ions impurities.