Electrostatic deposition of TiO2 nanoparticles on porous wood veneer for improved membrane filtration performance and antifouling properties

Super hydrophilic and super oleophobic carbon nanotube/TiO2 composite membranes for efficient separation of algal-derived oil/water emulsions

The separation of oil from microalgae aqueous emulsions is a critical step in producing algal-derived biofuels and nutraceuticals. This study presents the development of super hydrophilic and super oleophobic composite membranes to efficiently separate algal oil from oil/water emulsions. Carbon nanotubes (CNTs) were functionalized with polydopamine (PDA), polyethylene glycol (PEG), and titanium dioxide (TiO2) nanoparticles and coated onto a mixed cellulose ester (MCE) substrate to fabricate the composite membranes. Two distinct incorporation methods were employed for TiO2; direct nanoparticle incorporation and surface coating onto the CNT/PDA network. The membranes were comprehensively characterized using FTIR, SEM, EDS, contact angle measurements, and AFM analysis. The synthesized MCE@CNT/PDA/NP-TiO2 membrane exhibited super hydrophilicity with a water contact angle of 6.3° and underwater super oleophobicity with oil contact angles up to 172°. Membrane performance evaluation using a Nannochloropsis salina microalgae oil/water emulsion revealed excellent flux up to 9238 L m-2 h-1 bar-1 and oil rejection as high as 98.6 % for the TiO2-incorporated membranes. Additionally, these membranes demonstrated superior antifouling properties, maintaining over 90 % of initial flux even after five separation cycles. Incorporating TiO2 nanoparticles significantly enhanced the membrane's hydrophilicity, oleophobicity, antifouling capability, and stability under extreme pH conditions. The developed composite membranes show great potential for efficient and cost-effective separation of algal oil from microalgae cultivation systems.

Human Circulatory/Respiratory-Inspired Comprehensive Air Purification System

The circulatory and respiratory systems in humans are marvels of biological engineering that exhibit competence in maintaining homeostasis. These systems not only shield the organism from external contaminants but also orchestrate the vital gases via the bloodstream to sustain cellular respiration and metabolic processes across diverse tissues. It is noticed that spaces inhabited encounter challenges akin to those of the human body: protecting the indoor air from external pollutants while removing anthropogenic byproducts like carbon dioxide (CO2), particulate matters (PM), and volatile organic compounds (VOCs) tooutside. A biomimetic approach, composed of a microbubble-based gas exchanger and circulating liquid inspired by alveoli, capillary beds, and bloodstream of the human circulatory/respiratory system, offer an innovative solution for comprehensive air purification of hermetic spaces. Circulatory/respiratory-inspired air purification system (CAPS) ensure both continuous removal of PM and exchange of gas species between indoor and outdoor environments to maintain homeostasis. The effectiveness of this system is also supported by animal behavior experiments with and without CAPS, showing an effect of reducing CO2 concentration by 30% and increasing mice locomotor activity by 53%. CAPS is expected to evolve into robust and comprehensive air purification schemes through the networked integration of plural internal and external environments.

Thin-film nanocomposite membranes for efficient removal of emerging pharmaceutical organic contaminants from water

Membranes are receiving significant attention to remove emerging organic micropollutants (OMPs) from wastewater and natural water sources. Herein, we report the facile preparation of a novel thin-film nanocomposite (TFN) membrane with high permeability and efficient removal of OMPs. ZnO nanoparticles were first synthesized using the co-precipitation method and functionalized with N1-(3-Trimethoxysilylpropyl)diethylenetriamine to make the surface rich with amine groups and then synthesized nanomaterials were covalently cross-linked into the active layer during the interfacial polymerization (IP) process. The performance of the membranes containing the cross-linked ZnO was significantly better than the non-cross-linked ZnO NPs containing membranes. Adding multiple hydrophilic groups and entities on the surface significantly decreased the contact angle (from ∼60° to 20°). SEM images confirmed the uniform presence and homogeneous distribution of the functionalized NPs throughout the entire membrane surface. Zeta potential measurements showed the modified membranes have a lower negative charge than the pristine membranes. Filtration studies revealed a significant increase in permeability ascribed to the creation of nanochannels in the membrane's active layer. The modified membranes outperformed commercial NF membranes in removing four common OMPs with rejection efficiencies of ∼30%, 64%, 60%, and 70% for Sulfamethoxazole, Amitriptyline, Omeprazole, and Loperamide HCl, respectively. The higher removal efficiency was attributed to the weakened hydrophobic interactions due to the presence of hydrophilic moieties and a stronger size exclusion effect. Moreover, the modified membranes showed high resistance to bacterial adhesion in static conditions.

Biochar/layered double hydroxides composites as catalysts for treatment of organic wastewater by advanced oxidation processes: A review

Heterogeneous advanced oxidation process has been widely studied as an effective method for removing organic pollutants in wastewater, but the development of efficient catalysts is still challenging. This review summaries the present status of researches on biochar/layered double hydroxides composites (BLDHCs) as catalysts for treatment of organic wastewater. The synthesis methods of layered double hydroxides, the characterizations of BLDHCs, the impacts of process factors influencing catalytic performance, and research advances in various advanced oxidation processes are discussed in this work. The integration of layered double hydroxides and biochar provides synthetic effects for improving pollutant removal. The enhanced pollutant degradation in heterogeneous Fenton, sulfate radical-based, sono-assisted, and photo-assisted processes using BLDHCs have been verified. Pollutant degradation in heterogeneous advanced oxidation processes using BLDHCs is influenced by process factors such as catalyst dosage, oxidant addition, solution pH, reaction time, temperature, and co-existing substances. BLDHCs are promising catalysts due to the unique features including easy preparation, distinct structure, adjustable metal ions, and high stability. Currently, catalytic degradation of organic pollutants using BLDHCs is still in its infancy. More researches should be conducted on the controllable synthesis of BLDHCs, the in-depth understanding of catalytic mechanism, the improvement of catalytic performance, and large-scale application of treating real wastewater.

Effects of Shellac Self-Repairing and Carbonyl Iron Powder Microcapsules on the Properties of Dulux Waterborne Coatings on Wood

Magnetic carbonyl iron powder (CIP) microcapsules were created by in situ polymerization using melamine resin as the wall material and CIP as the core material. They were mixed with shellac self-repairing microcapsules to prepare dual-functional wood coatings, and the effect of different amounts of CIP microcapsules in the Dulux Waterborne primer on the performance of the primer was investigated. The findings demonstrated that the core-wall ratio had a significant impact on the characteristics of CIP microcapsules. The microcapsule coating rate reached 57.7% when the core-wall ratio was 0.65:1. The maximum reflection loss of CIP microcapsules with the core-wall ratio of 0.70:1 is -10.53 dB. When the addition amount of shellac self-repairing microcapsules is 4.2%, and the additional amount of CIP microcapsules with a core wall ratio of 0.65:1 and 0.70:1 is 3.0%, the coating color difference is the smallest. The number of microcapsules causes a noticeable drop in the coating's gloss, and the amount of microcapsules causes a small negative change in the coating's adherence. With an increase in the number of microcapsules, the coating's hardness, impact resistance, and tensile resistance first rose and subsequently fell. When the content of CIP microcapsules with core-wall ratio of 0.65:1 and 0.70:1 was 9.0%, the hardness, elongation at break and repair rate of the coating reached the best performance. According to a comprehensive analysis, when the content of CIP microcapsules with core-wall ratio of 0.70:1 is 9.0%, the coating has good performance. At this time, the coating has a color difference of 1.83, a glossiness of 19.3, an adhesion of 2 H, a hardness of 3 H, an impact resistance of 17 kg·cm, and a repair rate of 33.3%. This provides a technical basis for the application of multifunctional coatings on wooden substrates.