Antifouling thin-film nanocomposite NF membrane with polyvinyl alcohol-sodium alginate-graphene oxide nanocomposite hydrogel coated layer for As(III) removal

Synthesis and characterization of three-dimensional graphene oxide-chitosan/ glutaraldehyde nanocomposites: Towards adsorption of crocin from saffron

Despite the unique properties of graphene oxide (GO) as a green adsorbent, its low structural stability presents a drawback. This study aimed to modify the properties of GO through its functionalization with chitosan (CH), cross-linked with glutaraldehyde (GLU), and synthesized via the freeze-drying method (GO-CH/GLU). Microscopic analysis illustrated that covering the GO sheets with CH and nanoparticles (NPs) resulted in a 15.8 % increase in d-spacing and a 600 % increase in sheet thickness. The GO-CH/GLU composite was utilized for the separation/purification of crocin from saffron extract under varying pH (5-9), temperature (298-318 K), stirring rate (100-300 rpm), and crocin concentration (25-200 mg/mL). The Freundlich isotherm and pseudo-second-order kinetic models provided a good fit for crocin adsorption. Thermodynamic analysis revealed that the process was endothermic, spontaneous, and physical. Optimal adsorption conditions in batch mode were pH 7, a stirring rate of 300 rpm, a temperature of 318 K, and a crocin concentration of 100 mg/mL. These conditions were applied in a continuous system, resulting in a crocin separation efficiency of 94.17 % at 180 mL/h. Additionally, HPLC data indicated that the purity of separated crocin exceeded 90 %. So, the GO-CH/GLU composite is a promising and economical adsorbent for the food industry.

Prevention and Control of Biofouling Coatings in Limnoperna fortunei: A Review of Research Progress and Strategies

The increasing environmental concerns of conventional antifouling coatings have led to the exploration of novel and sustainable solutions to address the biofouling caused by Limnoperna fortunei. As a rapidly expanding invasive species, the fouling process of Limnoperna fortunei is closely associated with microbial fouling, posing significant threats to the integrity of aquatic infrastructure and biodiversity. This review discusses recent progress in the development of non-toxic, eco-friendly antifouling coatings that are designed to effectively resist biofouling without using toxic chemicals. Recent research has focused on developing novel non-toxic coatings that integrate natural bioactive components with advanced material technologies. These formulations not only meet current environmental standards and exhibit minimal ecological impact, but also possess significant potential in preventing the attachment, growth, and reproduction of Limnoperna fortunei. This review aims to provide scientific guidance by proposing effective and sustainable solutions to address the ecological challenges presented by Limnoperna fortunei. The insights gained from current research not only reveal novel antifouling methods, but also identify key areas for further investigation aimed at enhancing performance and environmental compatibility.

Influence of graphene oxide additives on the NF separation of triazine-based H2S scavenging compounds using advanced membrane technology

This work proposes an innovative approach for the membrane separation of spent and unspent H2S scavengers (SUS) derived from the application of MEA-triazine in offshore oil and gas production. Modified nanofiltration membranes were fabricated by incorporating graphene oxide (GO) and polyvinyl alcohol (PVA) into a thin film composite (TFC) to obtain a thin film nanocomposite (TFN) with enhanced permeability. In addition, various immobilization strategies for GO were investigated. The performance of the membranes and the effect of the GO loading were evaluated in terms of permeability, fouling propensity, and rejection of key components of the SUS, i.e., MEA-triazine (unspent scavenger), dithiazine (spent scavenger), and monoethanolamine, operating on a sample of SUS wastewater obtained from an offshore oil and gas platform. Various characterization techniques, such as contact angle, FTIR, XRD, SEM, TGA, and AFM, were employed to evaluate the structure, composition, and hydrophilicity of the membrane. The results show a remarkable increase in permeability (from 0.22 Lm-2 h-1 bar-1 for the TFC to 5.8 Lm-2 h-1 bar-1 for the TFN membranes), due to the enhanced hydrophilicity from GO incorporation. The strong interfacial interaction between GO and PVA within the TFN membrane results in negligible nanofiller leaching. The incorporation of GO moderately increases the rejection of the unspent scavenger (63%-73%, 62%-79%, 62%-80%, and 68%-76%), while drastically increasing the rejection of the spent scavenger, which is approximately null for the TFC membrane without GO and increases up to 58% in the TFN membrane with GO. Therefore, while the proposed membranes cannot be used for the selective separation of the unspent form the spent scavenger, they can achieve substantial recovery of all the key components contained in the SUS to avoid their discharge into the sea.

Advances in Membrane Separation for Biomaterial Dewatering

Biomaterials often contain large quantities of water (50-98%), and with the current transition to a more biobased economy, drying these materials will become increasingly important. Contrary to the standard, thermodynamically inefficient chemical and thermal drying methods, dewatering by membrane separation will provide a sustainable and efficient alternative. However, biomaterials can easily foul membrane surfaces, which is detrimental to the performance of current membrane separations. Improving the antifouling properties of such membranes is a key challenge. Other recent research has been dedicated to enhancing the permeate flux and selectivity. In this review, we present a comprehensive overview of the design requirements for and recent advances in dewatering of biomaterials using membranes. These recent developments offer a viable solution to the challenges of fouling and suboptimal performances. We focus on two emerging development strategies, which are the use of electric-field-assisted dewatering and surface functionalizations, in particular with hydrogels. Our overview concludes with a critical mention of the remaining challenges and possible research directions within these subfields.

Preparation of chitosan/citral forward osmosis membrane via Schiff base reaction with enhanced anti-bacterial properties

In this study, hydrogels generated by the Schiff base reaction between citral and chitosan (CS) were used for the first time to improve the anti-bacterial property of forward osmosis (FO) membranes. The composite membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Water contact angle (WCA), Zeta potential and confocal laser scanning microscopic (CLSM). In the FO filtration experiment, the membrane performance of TFC-1 with 1 M sodium chloride solution as the draw solution and deionized water as the feed solution was the best, with the water flux of 25.54 ± 0.7 L m-2 h-1 and the reverse salt flux of 4.7 ± 0.4 g m-2 h-1. Although the hydrogel coating produced a certain hydraulic resistance, the flux of the modified membrane was only reduced by about 8%, compared with the unmodified membrane. However, the anti-bacterial property (Pseudomonas aeruginosa) and anti-fouling properties (bovine serum protein and lysozyme protein) of the modified membranes were improved, showing good antibacterial properties (99%) and flux recovery rate (over 90%). The modified method has the advantages of easy access to raw materials, simple operation and no risk of secondary pollution, which can effectively reduce the cost of chemical cleaning and extend the service life of the membrane. The modification of membrane by chitosan-based hydrogel is a promising option in the field of membrane anti-bacteria.

Photothermal Conversion of Hydrogel-Based Biomaterial

Traditional energy from fossil fuels like petroleum and coal is limited and contributes to global environmental pollution and climate change. Developing sustainable and eco-friendly energy is crucial for addressing significant challenges such as climate change, energy dilemma and achieving the long-term development of human society. Biomass hydrogels, which are easily synthesized and modified, have diverse sources and can be designed for different applications. They are being extensively researched for their applications in artificial intelligence, flexible sensing, biomedicine, and food packaging. The article summarizes recent advances in the preparation and applications of biomass-based photothermal conversion hydrogels, discussing the light source, photothermal agents, matrix, and preparation methods in detail. It also explores the use of these hydrogels in seawater desalination, photothermal therapy, antibacterial agents, and light-activated materials, offering new ideas for developing sustainable, efficient, and advanced photothermal conversion biomass hydrogel materials. The article concludes with suggestions for future research, highlighting the challenges and prospects in this field and paving the way for developing of long-lasting, efficient energy materials.