A Simple Approach to Prepare Carboxycellulose Nanofibers from. Untreated Biomass. (Supporting Information)

Transcription

1 A Simple Approach to Prepare Carboxycellulose Nanofibers from Untreated Biomass (Supporting Information) Priyanka R. Sharma, Ritika Joshi and Benjamin S. Hsiao* Department of Chemistry Stony Brook University Stony Brook, NY-00, USA 0 * Corresponding author. Tel: +, benjamin.hsiao@stonybrook.edu

2 Nanofibers form Agglomerates at Low ph Values A B C 0 Figure S. Photographs showing carboxycellulose nanofibers in suspension (0.0 wt%) at (A) ph = (B) ph = (C) ph =. 0 Figure S illustrate the photographs of carboxycellulose nanofiber suspensions (0.0 wt%) obtained from N NaOH-treated jute fibers at different ph values. At ph =, the suspension appears milky, most probably due to the agglomeration of nanofibers in the presence of an excess H + and COOH groups on the fiber surface. The suspension becomes less milky at ph = and appears transparent at ph >. This behavior suggests that these nanofibers (with COOH groups) have a high tendency to aggregate at ph values below.

3 Morphology and Impurity of Untreated and Based Treated Jute Fibers The morphological investigation of untreated biomass fibers and base (N NaOH) treated fibers were carried out by a Zeiss LEO 0 SFEG-SEM instrument, which contained an In-Lens Secondary Electron Detector, a standard E-T detector, and a Rutherford Backscatter Electron Detector. The instrument was also equipped with an EDS (energy dispersive X-ray spectroscopy) system using an EDAX detector, which provided elemental compositions and X-ray maps of the various phases of the materials examined. 0 Figure S. SEM of jute fibers used as a source to prepare carboxycellulose nanofibers: (A) untreated jute fibers and (B) base treated jute fibers.

4 Figure S. EDS of SEM of untreated jute fibers used in Figure S(A). Figure S. EDS of SEM of base treated jute fibers used in Figure S(B).

5 Simple Energy and Material Cost Estimates of the New Approach 0 Based on our bench experiements using untreated jute fibers, laboratory chemicals and equipment, we have made simple estimates regarding the electric energy consumption, water consumption and production cost for fabrication of carboxycellulose nanofibers. These estimates, which will be substantially lower in large scale industrial production, clearly indicate that the demonstrated appraoch has tremendous potential to offer low-cost and effective pathways to produce carboxycellulsoe nanofibers directly from untreated biomass. We have not made any attempt to estimate the expenses related to man-power and equipment. However, as the demonstrated process only involved conventional glassware and the use of an acid resistant hood, we do not see any major issues in scale up production. The laboratory instruments used in this study were: magnetic stirrer (Thermofisher): 0 V,. A and 0 Hz; oven (Fisher Scientific): 0 V,. A and 0-0 Hz; homogenizer (Thermofisher): 0 V, 0-0 Hz,.0 A; and centrifuge (Fisher Scientific): 0 V and 0-0 Hz.

6 Nitric acid-sodium nitrite method: Bench experiments calculation Figure S. Estimates on the materials cost and consumption of energy for fabrication of jute carboxycellulose nanofibers using nitric acid-based approach, according to our bench experiments. The overall energy consumption was. kwh. 0

7 TEMPO oxidation method: Bench experiments calculation Figure S. Estimates on consumption of energy for fabrication of jute carboxycellulose nanofibers using TEMPO oxidation. The overall electrical consumption was. kwh/g. 0 Figure S illustrates the process diagram we used to estimate the material cost and electric energy consumptions for preparation of carboxycellulose nanofibers from g of untreated jute fiber using nitric acid and sodium nitrite, based on our bench experiments. Figure S illustrates the diagram for preparation of carboxycellulose

8 nanofibers from g of untreated jute fiber using TEMPO oxidation (S, S). Compared with the energy results in Figures S and S, the electrical energy of the nitric-acid based method was only about % of the TEMPO method. If we assume the yield of the reaction is wt%, the material cost then becomes around $. for producing g of carboxycellulose nanofibers. This cost is an order of magnitude cheaper than the TEMPO method involving bleaching and oxidation. We note that the lab scale energy consumption is significantly higher than the industrials operations (e.g., MFC produced from kraft and sulfite pulp ~ kwht - ; carboxymethylation of sulfite pulp ~ 00 kwht - ; enzymatic/refining of sulfite pulp ~ 00 kwht - ), which is expected. 0

9 Chemical Consumption Estimates Nitric acid-sodium nitrite method: Bench experiments calculation 0 Figures S. Estimates on consumption of chemicals for fabrication of jute carboxycellulose nanofibers using nitric acid and sodium nitrite based on our bench experiments. Total solvent used: nitric acid ( wt%): 0 ml; number of chemical used: maximum (nitric acid, or nitric acid and sodium nitrite); estimate water consumption: 00 ml (no use of alcohol); amount of chemical used: 0. g to produce g of carboxycellulose nanofibers.

10 TEMPO Oxidation: Bench experiments calculation 0 Figure S. Estimates on consumption of chemicals for fabrication of jute carboxycellulose nanofibers using TEMPO oxidation based on our bench experiments. Total solvent used: ml (0 ml water (0. g, wt%) + ml DMSO in pretreatment step + 00 ml water); number of chemical used: minimum (NaOH, DMSO, TEMPO, NaBr, NaClO, Na CO, ethanol); amount of chemical used:. g (0. g NaOH + 0. g NaBr g TEMPO + g NaClO ); water used: 00 ml X times = 00 ml (water consumption calculation was based on our laboratory experiments, not explained in reference S and S). NaOH: sodium hydroxide; DMSO: dimethyl sulfoxide; NaBr: sodium bicarbonate; TEMPO:,,,-Tetramethylpiperidin-- yl) oxyl; NaClO : sodium hypochlorite. 0

11 Figures S and S illustrate the process diagrams we used to outline the consumption of varying chemicals for fabrication of jute carboxycellulose using nitric acid/sodium nitrite and TEMPO oxidation, respectively. The new nitric acid/sodium nitrite method can lead to significant reduction in chemicals, reduction in solvents, and reduction in water usage (by about %). The calculations were made based on bench experiments in our lab. The Potential of Using Effluent as Fertilizer Source 0 The effluent in the new apprach can be easily neutralized using sodium hydroxide salts or potassium hydroxide to produce nitrogen rich salts that can be used as argricuture fertilizers. An demonstrated process to neutralize the effluent, consisting of degraded cellulose (sugar molecules), by-products of hemicellulose and lignin, nitrites and nitrates, is illustrated in Figure S. In this process, 00 g of sodium hydroxide was added to 000 ml of the effluent to adjust the ph value to., where acetone (: v/v) was added to the effluent to preciptate the salt. The obtained salt was g from 000 ml of the effluent. Although, acid and sodium nitrite were used in this process, the whole process could be further imporved to become a green approach. 0

12 Figure S. Estimate on preparation of salt obtained from the effluent produced during preparation of carboxycellulose nanofibers (. g) using the nitric acid and sodium nitrite method. The elemental Analysis carried out using Thermo EA Elemental Analyzer indicated the effluent contained N =.0%; C =.%, and NO - /NO - = mg/l.

13 TEM Image of Carboxycellulose Nanofibers from Spinifex Fibers 0 Figure S0. TEM Image of carboxycellulose nanofibers (carboxylate form) extracted from untreated spinifex fibers using the nitric acid and nitrite method. The average fiber width was. ± 0. nm and the average fiber length was ± nm based on the measurement of 0 nanofibers, using ImageJ software.

14 0 Figure S. TEM Image of carboxycellulose nanofibers (carboxyl form-before bicarbonate form) extracted from base treated jute fibers using the nitric acid and nitrite method. Fibers were highly agglomerated, difficult to find average length of fibers. The average fiber width was. ± 0. nm based on the measurement of nanofibers. Notable Differences between TEMPO and Nitric Acid-Based Methods The process developed in this study also dealt with the oxidation of cellulose at the C position. Therefore, it is important to compare the general features of the new nitric 0 acid-based method with the popular and reliable TEMPO oxidation method for treating untreated jute fibers (Table S).

15 Table S. Notable differences between the demonstrated nitric acid/sodium nitrite method and the TEMPO method for fabrication of carboxycellulose nanofibers from untreated jute fibers. Nitric Acid Method TEMPO Oxidation Source Untreated biomass Delignified and bleached biomass Number of steps - At least Electrical Energy. kwh/g. kwh/g Amount of chemical used (g/g of cellulose nanofibers) 0. g Sodium nitrite. g (0. g NaOH + 0. g NaBr g TEMPO + g NaClO ) Solvent used Toxic chemicals used Reagents availability and cost Vigorous mechanical treatment for 0 ml Nitric acid ml (NaOH ( wt%, 0 ml) + DMSO ( ml) + water (00 g~00 ml) Nitric acid or sodium nitrite Alkali, sodium chlorite (at least cycles), sodium hypochlorite, DMSO, TEMPO reagent Large scale production; relatively inexpensive No need Scalable TEMPO production; relatively more expensive Require fibrillation Crystallinity Low crystallinity (%) Higher crystallinity (> %) Behavior at ph Mostly agglomerates Gelation Lignin Present (trace amount) No Yield (based on cellulose percent) Degree of polymerization (DP) Effluent treatment Recycled product < 0 % > 0 % ~00 - Effluent can be recycled and neutralized by using sodium hydroxide and potassium hydroxide Nitrogen rich salt (.0%; NO - /NO - = mg/l) Reduction treatment and ion exchange resin treatment followed by electrodialysis. Salt by-products can be recycled back into hypochlorite via ozone treatment Salt by-products

16 Carboxycellulose Nanofibers as Effective Adsorbents to Remove Metal Ions 0 (A) (B) Figure S. Photograph showing remediaion efficiency of carboxycellulose nanofibers produced from jute fibers using nitric acid-sodium nitrite method (A) ml of 0. wt% jute carboxy cellulose after mixing of g of 0.0 wt% denatured uranyl acetate solution (B) ml distilled water with g of 0.0 wt% uranyl acetate solution. 0 Figure S shows the efficiency of carboxycellulose nanofibers, produced from jute fibers using nitric acid-sodium nitrite method, to remediate heavy metal ions, such as uranium impurities from water. On addition of uranium acetate solution to the nanofibers suspension, an immediate coagulation (yellow preciptation) took place as seen in image (A), whereas the no coagulation was observed with addition in distill water (image (B)). The experiment demonstrates the usefulness of using inexpensive

17 carboxycellulose nanofibers for removal of toxic meta ions from contanminated water sources. References S. Lin, J.; Yu, L.; Tian, F.; Zhao, N.; Li, X.; Bian, F.; Wang, B. Carbohydr. Polym. 0, 0, -. S. Cao, X.; Ding, B.; Yu, J.; Al-Deyab, S. S. Carbohydr. Polym. 0, 0,0-00.