Sulfonic Group Content Research Articles

'In situ' formation and voltammetric characterization of polymeric linear [(Mn(H2O)3)2(H2W12O42)]n6n- polyoxometalates in vertically-oriented mesoporous silica thin films

We present in this paper the 'in situ' preparation of manganese-containing polyoxotungstate [Mn(H2O)3)2(H2W12O42)]n6n- (1) chains in vertically-oriented mesoporous silica thin films on indium-tin oxide (ITO) electrodes. Taking advantage of a soft sequential method allowing the formation of 1 inside the mesoporous matrix, we succeed in its 'in situ' formation according to two main steps: (i) a first one consisting of the immobilization of [Mn(H2O)6]2+ in sulfonate-functionalized silica thin films; and (ii) a second one involving the reaction of the [Mn(H2O)6]2+ moieties with Na2WO42H2O. The electrochemical characterization of the functionalized materials obtained clearly demonstrates that the content of sulfonate groups in the starting films is a critical parameter to get the expected electroactive [Mn(H2O)3)2(H2W12O42)]n6n- compound inside the silica nanochannels. The experimentally determined chemical composition of the films performed by X-ray Photoelectron spectroscopy (XPS) is in good agreement with the expected composition of 1 in the case of films obtained with the optimal content of sulfonate functions (i.e., 5–6.5 % sulfonate with respect to silica). Energy Dispersive analysis of X-rays coupled with Transmission Electron Microscopy (TEM-EDX) carried out on the cross section of the films show that a uniform composition in terms of Mn/W ratio is obtained after the functionalization process. This confirms the formation of [Mn(H2O)3)2(H2W12O42)]n6n- uniformly within the whole thickness of the silica film (i.e., 80 nm), explaining also the long-range charge transfer reactions occurring through such insulating silica membrane. Using sulfonated silica films as template, we develop a robust 'in situ' synthesis strategy to assemble 1D linear polyoxotungstates onto ITO electrodes, exhibiting a stable electrochemical response once confined within the silica nanochannels.

Multi-site sulfonation of lignin for the synthesis of a high-performance dye dispersant

Sulfonated lignin-based dye dispersants have intensively attracted attention due to their low cost, renewability and abundant sources. However, their utilization is limited by the low content of sulfonic groups and high content of hydroxyl groups in their complex lignin structure, which results in various problems such as high reducing rate of dye, severe staining of the fibers and uneven dyeing. Here, the multi-site sulfonated lignin-based dispersants were prepared with high sulfonic group content (2.20 mmol/g) and low hydroxyl content (2.43 mmol/g). When using it as the dispersant, the dye uptake rate was improved from 69.23 % to 98.55 %, the reducing rate was decreased from 20.82 % to 2.03 %, the K/S value was reduced from 0.69 to 0.02, and the particle sizes in dye system before and after high temperature treatment were stabilized below 0.5 μm. Besides, the dispersion effect was significantly improved because no obvious separation between dye and water was observed even if without the assistance of grinding process. In short, the multi-site sulfonation method proposed in this work could remarkably improve the performances of the lignin-based dye dispersants, which would facilitate the development of the dye dispersion and the high value utilization of lignin.

Preparation and performance of 10 wt% of chlorantraniliprole Nano-suspension concentrate (SC) using polyether amine-bridged sulfonated alkali lignin (PSAL) as a dispersant

Polyether amine-bridged sulfonated alkali lignin (PSAL) with different sulfonic group contents and molecular weights was firstly synthesized and characterized. Then, 10 wt% of chlorantraniliprole Nano-suspension concentrate (SC) was prepared by the water-based grinding method, and the optimum grinding parameters were explored and obtained. Based on this optimum grinding formula, chlorantraniliprole Nano-SC was prepared and three optimum dispersants were finally obtained as follows: the compounds of polycarboxylate D-2 separately with P1SAL0.68, P1SAL0.84 and TERSPERSE 2500 at the mass ratio of 1:1. All Nano-SC prepared by these three dispersants had a D90 particle size below 200 nm, suspension percentage above 99%, water separation proportion below 1%, excellent thermal storage stability, and also better wettability on banana leaf surface. Additionally, adding glycerin could effectively inhibit the agglomeration and austenogenization of pesticide nanoparticles, and thus improve the stability of Nano-SC. Finally, the farmland experiments indicated chlorantraniliprole Nano-SC prepared in this work had a significantly improved pesticide effect on first-instar rice leaf rollers than traditional micron-sized SC. This work provided a new dispersant with excellent performance for chlorantraniliprole Nano-SC as well as broadened the high value-added utilization of industrial lignin into pesticide Nano-SC field, which had great economic and environmental benefits.

Impact of Formulation of Photocurable Precursor Mixtures on the Performance and Dimensional Stability of Hierarchical Cation Exchange Membranes.

This work presents a systematic approach to formulating UV curable ionomer coatings that can be used as ion-exchange membranes when they are applied on porous substrates. Ion-exchange membranes fabricated in this way can be a cost-effective alternative to perfluorosulfonic acid membranes, such as Nafion and similar thin ionomer film membranes. Hierarchically structured coated membranes find applications for energy storage and conversion (organic redox flow batteries and artificial photosynthesis cells) and separation processes (electrodialysis). Designing the ionomer precursor for membrane formulation requires the introduction of compounds with drastically different properties into a liquid mixture. Hansen solubility theory was used to find the solvents to compatibilize main formulation components: acrylic sulfone salt (3-sulfopropyl methacrylate potassium salt) and hexafunctional polyester acrylate cross-linker (Ebecryl 830), otherwise nonmiscible or mutely soluble. Among the identified suitable solvents, acrylic acid and acetic acid allowed for optimal mixing of the components and reaching the highest levels of sulfonic group content, providing the desired ion-exchange capacity. Interestingly, they represented a case of a reactive and nonreactive solvent since acrylic acid was built into the ionomer during the UV curing step. Properties of the two membrane variants were compared. Samples fabricated with acetic acid exhibit improved handleability compared with the case of acrylic acid. Acetic acid yielded a lower area-specific resistance (6.4 ± 0.17 Ohm·cm2) compared to acrylic acid (12.1 ± 0.16 Ohm·cm2 in 0.5 M NaCl). This was achieved without severely suppressing the selectivity of the membrane, which was standing at 93.4 and 96.4% for preparation with acetic and acrylic acid, respectively.

Aggregation behavior and dispersion stability of amphiphilic water-dispersed polyesters in aqueous solution

Amphiphilic polymer water-dispersed polyester (WPET) has important applications in the textile field. Due to the potential interactions among WPET molecules, the stability of their colloids is susceptible to external factors. This study focused on the effects of two hydrophilic groups (sulfonate group and PEG) on the aggregation behavior of WPET. In addition, the effects of concentration, temperature, and electrolytes on WPET aggregation behavior were systematically investigated. The more sulfonate group content in WPET, the higher stability with or without high electrolyte concentration it has. However, there is no clear correlation between the effect of PEG content and the dispersion stability of the WPET solution. The sulfonate group content in WPET is an important factor affecting its dispersion in aqueous solution. Meanwhile, WPET concentration, temperature, and electrolyte play important and complex roles in controlling the aggregation behaviors of the WPET. This fundamental research can be used to effectively control and improve the stability of WPET solutions and provide guidance for the prediction of dispersion and stability for molecules not yet synthesized.

In situ sulfonation steam explosion: energy efficient for lignocellulosic micro/nanofibrils production

To valorise the waste of Posidonia oceanica, a dominant sea grass in the Mediterranean Sea, the production of cellulose micro/nanofibrils with high lignin content (LCM/NF) is carried out in this work. The aim of this study is to evaluate the effect of lignin sulfonation conditions (impregnation conditions, time and temperature) on Posidonia fibres. This reaction is conducted in situ by using a steam explosion which is considered as an energy efficient process. Depending on the experimental conditions, sulfonated pulps are obtained with sulfonic group contents between 70 and 130 µmol/g, then used to produce LCM/NF by twin-screw extrusion and grinding. To investigate the quality of the produced LCM/NF, several techniques are used to study their morphological, structural and mechanical properties. Sulfonated LCM/NF result in nanopapers having high elastic modulus (between 5 and 6 GPa) with reduced energy consumption. The sulfonation could be considered as a mild pretreatment for preparing LCM/NF with properties.

Introducing dense sulfonic acid in metal–organic framework for effective adsorption of radioactive barium ion

The irreversible adsorption of radioactive barium (Ba2+) ion is highly necessary while still faces large challenge especially in adsorption capacity. In this work, we report two novel adsorbents, Zr-MSA-SO3H (MSA, 2-mercaptomalic acid) and Zr-DMSA-SO3H (DMSA, meso-dimercaptosuccinic acid). Due to the nanoscale particle and higher content of active sulfonic acid group, Zr-DMSA-SO3H exhibits rapid adsorption equilibrium (30 min) and higher adsorption capacity for Ba2+ (224.0 mg g−1), superior to other reported MOFs. Optimal adsorption happens at neutral pH and higher temperature can promote the adsorption. Besides, co-existing metal ions exhibit negligible effects on the adsorption. The combination of FTIR and XPS analysis confirms the dominant contribution of sulfonic acid group on Ba2+ adsorption. Our work proves Zr-DMSA-SO3H can serve as a potential adsorbent for Ba2+, and proposes a design strategy for MOFs with dense sulfonic acid groups.

Self-Assembly Properties and Aggregation Behavior of Amphiphilic Water-Dispersed Polyester with Different Contents of Sulfonate Groups in an Aqueous Solution.

Amphiphilic polymer water-dispersed polyester (WPET) has an important application value in the textile field. However, due to the potential interactions among water-dispersed polyester (WPET) molecules, the stability of their solution is susceptible to external factors. This paper focused on the self-assembly properties and aggregation behavior of amphiphilic water-dispersed polyester with different contents of sulfonate groups. In addition, the effects of WPET concentration, temperature, and Na+, Mg2+, or Ca2+ on WPET aggregation behavior were systematically investigated. The results show that compared with the low sulfonate group content of WPET, the high sulfonate group content of the WPET dispersion has higher stability with or without a high electrolyte concentration. In contrast, dispersions with low sulfonate group content are very sensitive to electrolytes and aggregate immediately at low ionic strength. WPET concentration, temperature, and electrolyte play important and complex roles in controlling the self-assembly properties and aggregation behavior of the WPET. The increase in WPET concentration can promote the self-assembly of WPET molecules. With the increase in temperature, the self-assembly properties for water-dispersed WPET are significantly reduced, resulting in enhanced stability. In addition, the electrolytes Na+, Mg2+, and Ca2+ in the solution can significantly accelerate the aggregation of WPET. This fundamental research on the self-assembly properties and aggregation behavior of WPETs can be used to effectively control and improve the stability of WPET solutions and provide guidance for the prediction of stability for WPET molecules not yet synthesized.

Preparation of a new gel-type lignin-based cationic adsorption resin for efficient removal of Ca2+ from aqueous solutions

Presently, most studies on modified lignin focused on the adsorption to heavy metal cations, but rarely to Ca2+ in hard water. Therefore, this work prepared a new gel-type lignin-based cationic adsorption resin (E-LSAF) through the crosslinking and curing of alkali lignin grafted by sodium sulfite sulfonated acetone to remove Ca2+ in water. Under the determined optimum synthesis conditions, E-LSAF with a highest sulfonic group content of 1.99 mmol/g was obtained. Structural and physicochemical measuring results showed E-LSAF was a gel-type resin, owning strong hydrophilicity, high mechanical strength, excellent thermal stability and acid-alkaline resistance. Adsorption results indicated the adsorption of E-LSAF to Ca2+ was well-fitted by Langmuir model, and the maximum adsorption capacity reached 45.8 mg/g. Pseudo-second-order model can describe this adsorption process well, suggesting it a chemisorption process. Dynamic column adsorption results showed E-LSAF could transform hard water into soft or even very soft water. The regeneration efficiency still maintained 80 % after 5 cycles. The adsorption mechanism was attributed to electrostatic attraction, ion exchange and complexation. This work provided a high-performance lignin-based cationic adsorption material with high adsorption capacity to Ca2+ and excellent acid-alkaline resistance, which filled the research gap of using modified sulfonated lignin to remove Ca2+ from water.

Water‐soluble Lignosulfonates: Structure, Preparation, and Application

AbstractAs one of the key raw materials that replace petroleum materials in today‘s world, biomass resources could be regarded as a promising resource. Currently, lignin and its derivatives are the only lignocellulosic biomass found to possess aromatic rings. Extending the application area of lignin requires overcoming the limitations of its low hydrophilicity. Sulfonation process becomes the most effective method for preparing lignosulfonates. An analysis of the mechanisms by which different lignosulfonates are prepared. It compared the effects of various modification methods on charge density and sulfonate group content in lignosulfonates. It also examined how different separation techniques affect the properties of lignosulfonates. As a result of being more water‐soluble, there is also a review of cutting‐edge research in the fields of energy, medicine, and agriculture. Also, the possible uses of lignosulfonate are talked about, and ideas are given for how this compound could be improved in the future.

Preparation of nano disperse dyes using sulfomethylated lignin: Effects of sulfonic group contents

The molecular simulation software was firstly applied to analyze the adsorption of sulfomethylated lignin (SAL) on dye surfaces. Then, SALs with different sulfonic group contents were prepared and characterized by FTIR, NMR, EA and GPC measurements using alkali lignin (AL) as raw materials and sodium sulfite as sulfonating agents. Next, SAL1.53 was determined to the optimum dispersant by TSI, particle size and thermal storage stability measurements, which had the smallest particle size of 173 nm and highest stability, comparable to the commercial Reax 85A lignin dispersant and basically satisfying the requirement of nano disperse dyes used in the digital printing technology. QCM, AFM and zeta potential results indicated that as the sulfonic group content of SAL increased, the adsorption mass, rigidity of the adsorbed layer, adsorption force and absolute zeta potential value all showed a gradually increasing tendency due to an enhanced hydrophilicity, and thus a decreased intermolecular agglomeration and an increased molecular chain stretching degree. A maximum was observed for SAL1.53. This research not only provided a novel approach to the preparation of high-performance lignin dispersants for nano disperse dyes, but also would broaden the high value-added industrial applications of biomass lignin into the digital printing and dyeing field.

Preparation of sulfomethylated lignin grafted by pyrrolidone for utilization as a dispersant in nano pigment paste

In this work, sulfomethylated lignin (SAL) was firstly synthesized using alkali lignin (AL) as raw materials, and then grafted with pyrrolidone as adsorption groups to prepare sulfomethylated lignin grafted by pyrrolidone (SALN). Results showed that SALN had a lower sulfonic group content than SAL but additionally contained 0.79 mmol/g of pyrrolidone groups. SAL and SALN were separately used as dispersants to prepare 20 wt% of cobalt blue nano pigment paste, and the minimum particle size of 82 nm and 52 nm was achieved when the dispersant dosage was 10 wt% and the grinding time was 4 h. After 7 days of thermal storage at 60 °C, the particle size of nano pigment paste prepared by SALN nearly remained unchanged, but that prepared by SAL increased from 82 nm to 285 nm, and there was obvious precipitation. Therefore, the thermal storage stability of cobalt blue nano pigment paste prepared by SALN was much better than that of SAL. Adsorption isotherm and infrared spectra experimental results indicated a firm multi-point anchoring complexing adsorption was formed between the pyrrolidone group of SALN and Co–O on cobalt blue surface, which made SALN not easy to desorb during collisions caused by Brownian motions. SAL was adsorbed through –C(=O)O−, and thus easy to desorb. Therefore, the stability of the nano pigment paste prepared by SALN was superior to that of SAL.

Maximizing the selectivity to triacetin in glycerol acetylation through a plastic waste-derived carbon catalyst development and selection of a reaction unit

Carbon catalysts derived from poly(ethylene terephthalate), PET, enriched with surface acidic sites were prepared and used in glycerol acetylation to increase the glycerol conversion and formation of higher acetins, i.e., diacetins and triacetin (DA and TA, respectively). Two approaches of carbon functionalization were applied – treatment with concentrated sulfuric acid or modification with benzenediazonium sulfonate (BDS) generated in-situ. The as-prepared carbons were characterized applying different techniques (e.g., elemental analysis, potentiometric titration, TG method, or XPS studies), and used as catalysts in glycerol esterification with acetic acid under different conditions. Using the synthesized carbons in the process carried out in a classical reaction mode (i.e., batch and reflux conditions, no water removal) enabled us to significantly increase the reaction rate and yields of the produced di- and triacetins compared to the reaction without a catalyst. The most active sample showed a high content of sulfonic groups and gave about 95 % conversion of glycerol and 55 and 20 % selectivity to DA and TA, respectively, just within 1 h of the process at 110 °C. Moreover, the used catalyst caused a significant increase in the TA yield when the reaction was performed with the addition of toluene compared to the toluene-free process. This was related to the continuous removal of water from the reactor and shifting the reaction equilibrium toward the higher esters as well as due to the perfectly-tailored properties of the obtained carbon sample.

In Situ Lignin Sulfonation for Highly Conductive Wood/Polypyrrole Porous Composites

AbstractTo address the rising need of sustainable solutions in electronic devices, the development of electronically conductive composites based on lightweight but mechanically strong wood structures is highly desirable. Here, a facile approach for the fabrication of highly conductive wood/polypyrrole composites through top‐down modification of native lignin followed by polymerization of pyrrole in wood cell wall. By sodium sulfite treatment under neutral condition, sulfonated wood veneers with increased porosity but well‐preserved cell wall structure containing native lignin and lignosulfonates are obtained. The wood structure has a content of sulfonic groups up to 343 µmol g−1 owing to in situ sulfonated lignin which facilitates subsequent oxidative polymerization of pyrrole, achieving a weight gain of polypyrrole as high as 35 wt%. The lignosulfonates in the wood structure act as dopant and stabilizer for the synthesized polypyrrole. The composite reaches a high conductivity of 186 S m−1 and a specific pseudocapacitance of 1.71 F cm−2 at the current density of 8.0 mA cm−2. These results indicate that tailoring the wood/polymer interface in the cell wall and activating the redox activity of native lignin by sulfonation are important strategies for the fabrication of porous and lightweight wood/conductive polymer composites with potential for sustainable energy applications.

Preparation and Properties of Sulfonated Poly(phthalazinone ether ketone) Membranes for Electrodialysis.

Sulfonated poly(phthalazinone ether ketones) (SPPEK) with ion exchange capacities from 0.77 to 1.82 mmol·g−1 are synthesized via an electrophilic substitution reaction. Nuclear magnetic resonance and infrared absorption spectroscopy are used to characterize the chemical structure of the obtained polymers for confirming the successful introduction of sulfonic groups. SPPEKs show excellent thermal stability; their temperature required to achieve 5% weight loss is about 360 °C. Accordingly, the obtained membranes possess high ion perm-selectivity, proton conductivity, and low area resistance. Regarding the electrodialysis-related performance of the membranes, the SPPEK-4 membrane has the highest limiting current density (39.8 mA·cm2), resulting from its high content of sulfonic groups. In a desalination test of standard solution, SPPEK-3 and SPPEK-4 membranes exhibit both better salt removal rate and acceptable energy consumption than commercial membrane. Additionally, SPPEK-3 membrane shows outstanding performance in terms of high concentration rate and low energy consumption during saline water treatment, which indicates the feasibility of novel membranes in electrodialysis application.

A simple method for preparation of lignin/TiO2 nanocomposites by sulfonation degree regulation and their application in polyurethane films.

The waterborne polyurethane (WPU) exposed to outdoor environment for a long time are more likely to reduce their mechanical performance and service life. This work describes a simple and effective method to obtain the homogeneous lignin/TiO2 nanocomposite as the anti-UV additive to improve the applicability of WPU. The SKLs/TiO2 were prepared by the gradient sulfonation kraft lignin (SKLs) and tetrabutyl titanate. The particle morphology and hybrid structure of SKLs/TiO2 are characterized by FT-IR, zeta potential analysis, XPS, TG and SEM. Interestingly, it was found that the change of π-π interactions and electrostatic repulsion between SKL molecules effected the forming of SKLs/TiO2 nanocomposite. The lignin content and morphology of SKLs/TiO2 nanocomposite could be controlled by regulating the sulfonate group content on lignin molecular. Furthermore, the SKLs/TiO2 nanocomposites was successfully applied on water polyurethane film as the additive, when SKLs/TiO2 content increased from 0wt% to 5.0wt%, the tensile strength increased 43%, the elongation at break increased from 240.0% to 352.0% and the UV transmittance reduced from 87% to 1.7% below 400nm, which greatly improved the UV resistance and mechanical properties. The results of this study are of significant and practical importance to the high-value-added utilization of lignin.

Sulfonated polydivinylbenzene bamboo-like nanotube stabilized Pickering emulsion for effective oxidation of olefins to 1,2-diol

Sulfonated polydivinylbenzene bamboo-like nanotube (SPDVB) with effective olefins oxidation activity is prepared by combining cationic polymerization and sulfonation. By merely adjusting sulfonation time, SPDVB with different sulfonic acid group (–SO3H) contents is achieved. SPDVB is used as both a solid emulsifier and catalyst to fabricate Pickering emulsion interface catalytic system for oxidizing olefins with 30% H2O2 acting as oxidant/water phase and olefins acting as reactants/oil phase. It is shown that Pickering emulsion interface catalytic system stabilized by SPDVB exhibits enhanced olefins oxidation efficiency than the conventional ones. At the optimum catalyst and reaction condition, the conversion of olefins by Pickering emulsion interface catalytic system stabilized by SPDVB for cyclohexene, 1-methylcyclohexene, cyclooctene, 2,3-dimethyl-2-butene oxidation is higher than 90.00% and the corresponding 1,2-diol selectivity exceeds 93.00% except the selectivity to 1-methyl-1,2-cyclohexanediol. The catalytic system also exhibits excellent cycling performance (>95.00% olefins conversion and >89.00% 1,2-diol selectivity for cyclohexene/2,3-dimethyl-2-butene oxidation after four cycles). A possible mechanism for oxidation of olefins to 1,2-diol by SPDVB stabilized Pickering emulsion is proposed: the high catalytic interface area between sulfonic acid group and H2O2 in water phase enhances the sulfonic acid group of SPDVB to convert into peroxysulfonic acid (catalytic activity centre) firstly; then the formed peroxysulfonic acid attacks the double bond of olefins to form epoxide intermediates, which will be hydrolyzed to 1,2-diol.

Solid acid carbon catalysts for sustainable production of biofuel enhancers via transesterification of glycerol with ethyl acetate

SO3H-bearing carbons prepared from sugars or glycerol were used as catalysts for the production of acetins via a transesterification route. Two methods of preparation of functionalized carbon catalysts were compared: a) an energy-efficient, one-pot synthesis including partial carbonization of precursors with H2SO4 coupled with simultaneous in-situ functionalization and b) a two-step method including template synthesis of carbon followed by functionalization of the obtained product with sulfuric acid or diazonium salt. The synthesized carbons were used in an eco-friendly process of glycerol transesterification with ethyl acetate under different reaction conditions. All the prepared samples were found to effectively catalyze the reaction, producing a mixture of mono-, di- and triacetins (MA, DA and TA, respectively); however, the efficient production of the target compounds, namely DA and TA, which are valuable biofuel additives, was found to be strongly dependent on the content of sulfonic groups on the surface of these catalysts. A direct correlation between –SO3H concentration and glycerol conversion, as well as the yield of higher esters was established. Moreover, the applied method of one-pot combined partial carbonization and functionalization with H2SO4 was shown to be a convenient way to obtain carbonaceous solid acid catalysts that can be used as promising alternatives to modified carbons produced by conventional two-step techniques.

Ultrastructure of extracorporeal secretions of four sessile species of Rotifera (Gnesiotrocha), with observations on the chemistry of the gelatinous tube

AbstractSecretion of an extracorporeal hydrogel is a common defensive strategy employed by many aquatic invertebrates including several species of sessile rotifers. Here, we provide a comparative study of the ultrastructure of the gelatinous secretions of four species of Superorder Gnesiotrocha (Monogononta): Conochilus unicornis, Collotheca ferox, Stephanoceros fimbriatus, and Stephanoceros millsii. Additionally, we use differential staining and enzyme degradation assays to explore the chemistry of the gelatinous tube of S. fimbriatus. At least three types of secretions are produced by these four species: an external gelatinous tube, a thick glycocalyx, and an adhesive peduncle. These three different secretions all have a fibrous appearance, but each has different electron densities, fiber thicknesses, and glandular origins. The gel tube, which is likely secreted by pedal glands, has a highly hydrated framework of mesh‐like fibers with thick internal and external laminae that differ slightly among species. Chemical staining suggests that the gel tube is composed of glycoproteins with a high content of sulfonic groups and limited or no obvious lipids or cationic proteins. This tube is resistant to chemical and enzymatic digestion. The proteinaceous glycocalyx is secreted by the syncytial integument and has various densities and thicknesses among species. The peduncle is an adhesive attachment that connects a rotifer's foot to a substratum, or, in some species, to conspecifics as part of a colony. The secretion is highly electron dense and contains membrane‐bound vesicles; it appears to be derived from a different set of pedal glands than the hydrogel tube. The different chemistries and anatomical origins of the three gelatinous secretions suggest an independent evolutionary history for each.

EFFECT OF DEGREE OF SULFONATION IN NANOCELLULOSE/CHITOSAN COMPOSITE ON ADSORPTION OF CATIONIC DYE AS OPIOID SIMULANT

In this study, the effect of nanocellulose sulfonate group content on adsorption of an opioid simulant was tested. The opioid simulant used was Victoria blue R, an amine dye. Nanocellulose filters were fabricated by crosslinking cellulose nanocrystals (CNCs) with chitosan to improve the mechanical stability of freeze-dried CNCs. Thermogravimetric analysis confirmed the filter’s thermal stability and operating temperatures. Conductometric titration, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques were used to characterize the degree of nanocellulose functionalization. Lastly, the adsorption performance of the sulfonated nanocellulose filter was tested and fitted to kinetic models and adsorption isotherms. The adsorption of the dye by the sulfonated nanocellulose followed pseudo-second order kinetics and the Langmuir isotherm. The maximum adsorption of Victoria blue R dye by sulfonated nanocellulose (68.56 mg/g) is significantly higher than those of other adsorbents, like activated carbon (0.59-2.97 mg/g) and magnetic microparticles (40.98 mg/g). Thus, sulfonated cellulose nanocrystals are a promising material for the sequestration of opioids from water.