Facile preparation of three-dimensional macroporous network structured modified wood flour for efficient Pb(II) removal from aqueous solution: mechanism and economic assessment

Abstract

Utilizing plant wastes to treat Pb(II)-polluted water bodies offers a sustainable solution, but concerns over adsorption ability and separation efficiency limit its application. This study investigates the preparation and application of three-dimensional macroporous network-structured modified wood flour (WTX and TZX) for efficient Pb(II) removal. The adsorbents were synthesized through xanthate modification of defatted (TZ) and non-defatted (WT) wood flour, followed by lyophilization to achieve a stable porous structure. The optimal preparation condition involved mixing 1.0 g of original wood flour with 2 mL of CS₂ in a strong base environment at 25 °C for 3 h. Both WTX and TZX exhibited similar three-dimensional structure and good solid-liquid separation performance. Pb(II) removal rates reached 61 % for WTX and 54 % for TZX within 45 min. The maximum adsorption capacities were 221.73 mg/L for WTX and 210.53 mg/g for TZX, significantly higher than untreated wood flour. Despite similar appearances and maximum Pb(II) removal abilities, the defatting pretreatment did not enhance mechanical properties or adsorption performance. Pb(II) immobilization occurred via electrostatic attraction, complexation and precipitation, with functional groups like –O–C (=S)–SNa, –OH, –NH₂ and –COOH playing key roles. An economic assessment highlighted the cost-effectiveness of the adsorbents, with an estimated treatment cost of 3.21 US$/ton of wastewater. The study underscores the potential of waste wood flour biomass as a sustainable, low-cost solution for heavy metal remediation.