A self-assembling guar gum hydrogel for efficient oil/water separation in harsh environments

Investigation of synergistic effects incorporating esterified lignin and guar gum composite aerogel for sustained oil spill cleanup

The recently developed aerogel demonstrates a high capacity for pollutant absorption, making it an environmentally friendly option for oily water treatment. In an effort to reduce the adverse effects of the black liquor accumulation in the pulp industry, this study focused on utilizing the mentioned abundant bio-resource lignin, which can be applied to various high-value applications such as 3D porous materials for oil spill cleanup. Lignin, precipitated from the black liquor, was esterified using maleic anhydride as the esterifying reagent to enhance the hydrophobicity. Then, the composite aerogel fabricated from esterified lignin and guar gum (GG) was successfully prepared through the facile freeze-drying, using glutaraldehyde (GA) as the cross-linker. The resulting aerogel exhibited high porosity values exceeding 95%, low density (27.4 mg/cm3), and an impressive absorption capacity of 32.5 g/g for sunflower oil. These results demonstrate the potential of black liquor utilization as a bio-waste source of lignin and highlight the cost-effective guar gum-esterified lignin composite aerogel, which exhibits remarkable oil absorption capabilities and environmental sustainability promotion.

Bio-Inspired Functional Materials for Environmental Applications

With the global population expected to reach 9.7 billion by 2050, there is an urgent need for advanced materials that can address existing and developing environmental issues. Many current synthesis processes are environmentally unfriendly and often lack control over size, shape, and phase of resulting materials. Based on knowledge from biological synthesis and assembly processes, as well as their resulting functions (e.g., photosynthesis, self-healing, anti-fouling, etc.), researchers are now beginning to leverage these biological blueprints to advance bio-inspired pathways for functional materials for water treatment, air purification and sensing. The result has been the development of novel materials that demonstrate enhanced performance and address sustainability. Here, an overview of the progress and potential of bio-inspired methods toward functional materials for environmental applications is provided. The challenges and opportunities for this rapidly expanding field and aim to provide a valuable resource for researchers and engineers interested in developing sustainable and efficient processes and technologies is discussed.

Natural gums and their derivatives based hydrogels: in biomedical, environment, agriculture, and food industry

The hydrogels based on natural gums and chemically derivatized natural gums have great interest in pharmaceutical, food, cosmetics, and environmental remediation, due to their: economic viability, sustainability, nontoxicity, biodegradability, and biocompatibility. Since these natural gems are from plants, microorganisms, and seaweeds, they offer a great opportunity to chemically derivatize and modify into novel, innovative biomaterials as scaffolds for tissue engineering and drug delivery. Derivatization improves swelling properties, thereby developing interest in agriculture and separating technologies. This review highlights the work done over the past three and a half decades and the possibility of developing novel materials and technologies in a cost-effective and sustainable manner. This review has compiled various natural gums, their source, chemical composition, and chemically derivatized gums, various methods to synthesize hydrogel, and their applications in biomedical, food and agriculture, textile, cosmetics, water purification, remediation, and separation fields.

Mussel- and nacre-inspired dual-bionic alginate-based hydrogel coating with multi-matrix applicability, high separation stability and antifouling performance for oil/water separation

Natural hydrogel-modified porous matrices with superwetting interfaces are ideal for oil/water separation. In this study, inspired by two marine organisms, a novel hydrogel coating with multi-matrix suitability, high oil/water separation capability and antifouling properties was developed. Specifically, inspired by mussel byssus, hydrogel coating was successfully deposited on porous matrix surface based on the introduction of tannic acid (TA). Moreover, inspired by the "brick and mortar" microstructure of Pinctada nacre, silica particles were in-situ synthesized in the sodium alginate (SA)/Ca2+ hydrogel to provide the filling effect and to increase strength. Furthermore, Sodium alginate-tannic acid-tetraethyl orthosilicate (SA-TA-TEOS) hydrogel coating-modified membrane exhibited super-hydrophilic and underwater super-oleophobic performance (underwater oil contact angle >150°), and achieved efficient oil/water separation for four oil/water emulsions (flux = 493-584 L·m-2·h-1 and rejection = 97.3-99.5 %). The modified membrane also demonstrated good anti-fouling performance and flux recovery. Notably, hydrogel coating-modified non-woven fabric also had high oil/water separation capacity (rejection >98 %) and cyclic stability, which proved the universal applicability of this hydrogel coating. In short, this work provides new insights into the fabrication of hydrogel coating-modified porous materials based upon a marine organism biomimetic strategy, which has potential applications in separating oil/water emulsions in industrial scenarios.

Modulation of composite hydrogel consisting of TEMPO-oxidized cellulose nanofibers and cationic guar gum

The applications of hydrogels are prominently affected by the modulation of their structure and performance. We herein systematically implemented the modulation of an all-polysaccharide hydrogel consisting of TEMPO-oxidized cellulose nanofibers (TOCN) and cationic guar gum (CGG). Four different factors including the carboxylate content and size of TOCN, the freezing-thawing treatment and solid content of hydrogel were studied to disclose their influence on the structure and property of TOCN/CGG hydrogel. The results indicated that the increase of carboxylate content of TOCN, the number of freezing-thawing cycles and solid content all increased the crosslinking density of hydrogel as a result of the improved interactions. Accordingly, the hydrogels exhibited more compact structures and enhanced rheological properties. The influence of TOCN size on the hydrogel structure and property was demonstrated to be dependent on the compromise between the exposed functional groups of TOCN and their ability in generating entanglements inside the hydrogel. This work helps shed light on the modulation of hydrogel structure and performance, which might facilitate the exploration of hydrogel applications.

Quinoxaline-probe embedded injectable fluorogenic hydrogels: Comparative detection of mesitylene in guar gum and i-carrageenan hydrogels

The innovation of novel chemosensor probes for the recognition of trace volatile organic compounds is critical due to their hazardous effect on the environment and human health. A nitro-group integrated quinoxaline probe with a profound discriminative fluorescence 'turn-on' response to mesitylene was fabricated into guar gum and i-carrageenan, two biopolymer-based hydrogel matrices, to develop compact, portable fluorogenic hydrogel sensors and assess their fluorescence properties. A comparative characterization-based analysis of native, probe-associated, and probe-analyte-associated hydrogels, (comprising of FT-IR, XRD, TGA) was investigated to ascertain the overall compatibility of the hydrogel-based sensors for use as a smart rapid detection tool. Dynamic rheological measurements also validated the mechanical stability and robustness of the developed hydrogel matrices. Fluorescence spectroscopic investigations yielded promising results of 0.15 ppm limit of detection (LOD) in guar gum and 0.29 ppm LOD in i-carrageenan hydrogels respectively. FESEM and Fluorescence microscopy studies represented the morphological variations of the hydrogel sensors on interaction with mesitylene. The practical feasibility of the chemosensor in hydrogel form for mesitylene detection in the vapor phase was also explored. Probe-embedded hydrogels with injectable property was shown, depicting its use as security ink for information encryption functions. This approach of incorporating chemosensors into biobased hydrogel networks has the potential to broaden its opportunities in the field of chemical, biomedical, and environmental sensing sectors.

Guar gum, a low-cost sustainable biopolymer, for wastewater treatment: A review

Rapid population growth and the resultant pollution of freshwater resources have created a water stress condition reducing the availability of safe and affordable water. Guar gum, a biocompatible macromolecule obtained from the endosperm of the seeds of Cyamopsis tetragonolobus, is a fascinating raw material for multifunctional adsorbents. This review assembled the work conducted by various researchers over the past few decades and discussed the structure, properties, and different modifications methods employed to develop versatile guar gum-based adsorbent. The paper also summarized the recent progress of guar gum-based nanocomposites for the remediation of multiple hazardous substances such as organic dyes, toxic heavy metal ions, oil-water separation as well as inhibiting the growth of bacterial pathogens. Thus, the important contribution of guar gum composites to safeguard the water quality is highlighted which will overcome the limitations and streamline the future course of innovative research.

An Overview on Recent Progress of the Hydrogels: From Material Resources, Properties to Functional Applications

Hydrogels, as the most typical elastomer materials with three-dimensional network structures, have attracted wide attention owing to their outstanding features in fields of sensitive stimulus response, low surface friction coefficient, good flexibility and bio-compatibility. Because of numerous fresh polymer materials (or polymerization monomers), hydrogels with various structure diversities and excellent properties are emerging, and the development of hydrogels is very vigorous over the past decade. This review focuses on state-of-the-art advances, systematically reviews the recent progress on construction of novel hydrogels utilized several kinds of typical polymerization monomers, and explores the main chemical and physical cross-linking methods to develop the diversity of hydrogels. Following the aspects mentioned above, the classification and emerging applications of hydrogels, such as pH response, ionic response, electrical response, thermal response, biomolecular response, and gas response, are extensively summarized. Finally, we have done this review with the promises and challenges for the future evolution of hydrogels and their biological applications. cross-linking methods; functional applications; hydrogels; material resources This article is protected by copyright. All rights reserved.

Biomimicking properties of cellulose nanofiber under ethanol/water mixture

The two types of cellulose nanofiber (CNF) surface characteristics were evaluated by oil contact angle under ethanol-water solution at several concentrations as well as in air. Wood pulp-based 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-oxidized cellulose nanofiber (TOCNF) sheets and bamboo-derived mechanical counter collision cellulose nanofiber (ACC-CNF) sheets were fabricated by casting followed by drying. The CNF shows underwater superoleophobic mimicking fish skin properties and slippery surface mimicking Nepenthes pitcher. The underwater superoleophobic properties of CNF was evaluated theoretically and experimentally. The theoretical calculation and experimental results of contact angle showed a large deviation. The roughness, zeta potential, and water absorption at different concentrations were key factors that determine the deviation. Antifouling investigation revealed that CNF was a good candidate for antifouling material.

Preparation of an Intelligent Oleophobic Hydrogel and Its Application in the Replacement of Locally Damaged Oil Pipelines

In the pipeline transportation process for crude oil, the most important and popular maintenance method for perforated and ruptured oil pipelines is the replacement of the damaged pipeline segment. However, this method has several disadvantages, including a complex process, large time consumption, and excessively high costs. The present study reported the preparation of a strong cross-linking hydrogel that served as a temporary blocking material during the long-distance oil pipeline partial replacement process. The prepared product was characterized by infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy to analyze the microscopic reactions and structures. Orthogonal experiments for shear stress were performed to determine the optimal synthesis condition. The relevant experiments indicated that the proposed product can effectively isolate oil and oil gas, and a 4.5 m long hydrogel can resist the force of a 0.57 MPa overpressure. The blocked pipeline turned to a dredged state on changing the pipeline pressure. The flame resistance experiment showed that the hydrogel exhibited excellent flame resistance and could therefore ensure the safety of the hot work. On the basis of this hydrogel material, a new method for replacing the partially damaged oil pipeline was proposed.

A multifunctional self-crosslinked chitosan/cationic guar gum composite hydrogel and its versatile uses in phosphate-containing water treatment and energy storage

A new self-crosslinked composite hydrogel is prepared with chitosan (CS) and cationic guar gum (CGG), based on the imine and acetal chemistry for gelation. The CS/CGG hydrogel exhibits thermal/pH responsiveness, injectability, adhesiveness and good compressive strength. The hydrogel is effective in removing phosphate from wastewater through an adsorption process, during which KH₂PO₄ is used as a phosphate model. The adsorption complies with the Freundlich model, indicating that it is a multilayered process with complex adsorption mechanisms. Considering their porous structure and nitrogen/phosphorus heteroatoms doping, the phosphate-adsorbed hydrogels are made into porous N,P doped carbon aerogels that can be potentially used as electrodes for a supercapacitor. The results indicate that these carbon aerogels possess excellent capacitive performance (best specific capacitance of 302.2 ± 4.9 F/g), as well as good cycling stability after 5000 times of charging/discharging.