A novel cross-flow Ag/wood composite filter for high-concentration organic dye wastewater treatment

Abstract

Dye wastewater produced from industry production is difficult to degrade naturally. Natural wood possesses a hierarchical and three-dimensional (3D) interconnected microstructure, making it a desirable material for water treatment. However, limited water transport pathways can reduce the efficiency of removing high-concentration organic dyes. To address this, we present a low-cost, scalable, and efficient cross-flow Ag/wood composite filter by combing the structural design and hydrothermal treatment using a silver-ammonia solution. Silver ions (Ag⁺) are effectively reduced to silver nanoparticles (Ag NPs) by wood lignin and then anchored by hydroxyl groups in the cellulose and hemicellulose of the wood. Importantly, the incorporation of Ag NPs does not compromise the 3D porous structure of the wood. Diagonal grooves and exposed channels on both sides of the filter guide pollutants, ensuring extensive interaction with Ag NPs along elongated reaction pathways and through microstructural vessel disturbances. An 8 mm-thick cross-flow Ag/wood composite filter, featuring grooves with a diameter of 15 mm and a depth of 4 mm, achieves a remarkable 99% degradation efficiency of methylene blue (MB) at a water flux of up to 1775 L/(m²∙h). The performance in water flux and decolorization efficiency hinges significantly on groove diameter, groove depth, and filter thickness. This cross-flow Ag/wood composite filter represents a promising advancement for rapid and effective removal of various organic pollutants in a single-step process, showcasing extensive potential for applications in water treatment. This work aims to enhance clarity and readability while maintaining the technical details and impact of the research.