A novel functionalized cellulose paper for wastewater treatment: Exploring its multifunctional capabilities through TA-APTES-mediated surface engineering

Considering the complexity of wastewater contaminants, there is an urgent demand for fabricating multifunctional materials with high efficiency through environmentally friendly and facile approaches. Herein, a novel functionalized cellulose paper (CP/TA-APTES) was successfully fabricated through the integration of cellulose paper (CP) with tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) using an impregnation method. Subsequently, CP/TA-APTES was introduced as a reducing agent to reduce silver ammonia ions. Silver nanoparticles (Ag NPs) were then deposited on the surface of CP/TA-APTES, endowing the paper (CP/TA-APTES/Ag) with excellent catalytic activity and antibacterial properties. The MB dye was reduced via CP/TA-APTES/Ag, and the corresponding rate constant was determined to be 0.0118 s^-1, indicating a high level of catalytic activity. In addition, the CP/TA-APTES/Ag demonstrated remarkable antibacterial properties against a variety of pathogenic bacteria. Superhydrophobic cellulose paper (CP/TA-APTES/ODA) was successfully synthesized through the chemical modification of CP/TA-APTES using octadecylamine (ODA), accomplished via Michael addition or Schiff base reactions, resulting in a material with enhanced surface hydrophobicity and structural stability. Notably, the CP/TA-APTES/ODA exhibited outstanding superhydrophobic and superoleophilic characteristics, as demonstrated by an impressive water contact angle reaching up to 155.6°, coupled with an oil contact angle (OCA) of 0°. Remarkably, the material maintained its superhydrophobic functionality even under severe chemical and mechanical conditions. Moreover, the surface of superhydrophobic CP/TA-APTES/ODA exhibited resistance to the adhesion of dye solutions and powders, demonstrating its superior self-cleaning and anti-fouling capabilities. Due to the favorable properties, the CP/TA-APTES/ODA was utilized as an oil-water separation material, demonstrating the ability to efficiently separate a wide range of oil-water mixtures solely through gravitational force, with separation efficiencies exceeding 98.61% and fluxes ranging from 336.45 to 9554.14 L m^-2·h^-1. More importantly, it exhibited excellent recyclability, with a separation efficiency remaining above 94.14% and a flux exceeding 310.13 L m^-2·h^-1 even after ten consecutive cycles. This cost-effective, environmentally sustainable, and multifunctional cellulose-based paper not only facilitated the rational and high-value utilization of natural cellulose, but also offered a viable solution to the challenge of complex wastewater treatment.