Magnetically Modified Wood Fiber with Acrylic Polymers as an Efficient Adsorbent for Removing Methylene Blue and Rhodamine B

Industrial pigment wastewater poses a serious threat to ecosystems and human health. This study aimed to develop efficient and recyclable adsorbents for the treatment of such wastewater. Initially, a magnetic carrier, W@Fe 3 O 4 , was synthesized by loading Fe 3 O 4 onto wood fibers (W) via co-precipitation. Subsequently, three types of acrylic-modified magnetic wood fiber adsorbents (W@Fe 3 O 4 -g-pGMA, W@Fe 3 O 4 -g-pAA, W@Fe 3 O 4 - g -pHEMA) were fabricated by grafting poly(glycidyl methacrylate) (pGMA), poly(acrylic acid) (pAA), and poly(2-hydroxyethyl methacrylate) (pHEMA), respectively, onto the W@Fe 3 O 4 surface through surface-initiated polymerization. The successful preparation of the materials was confirmed by FTIR, TG, and SEM. Adsorption experiments demonstrated a significant enhancement in the adsorption performance of all three modified materials for Methylene Blue (MB) and Rhodamine B (Rh B). The optimal adsorption conditions were identified as follows: adsorbent dosage of 10 mg, initial MB concentration of 20 mg/L, initial Rh B concentration of 30 mg/L, pH 7, and temperature of 35 °C. Under these optimal conditions, the removal efficiency of MB by W@Fe 3 O 4 - g -pGMA reached 83.47%, with an adsorption capacity of 16.15 mg g −1 , while the removal efficiency of Rh B by W@Fe 3 O 4 - g -pAA reached 90.08%, with an adsorption capacity of 17.95 mg g −1 . The adsorption kinetics were best described by the pseudo-second-order model. Isotherm analysis indicated that the adsorption of MB onto W@Fe 3 O 4 - g -pGMA was better fitted by the Langmuir model, whereas the adsorption of Rh B onto W@Fe 3 O 4 - g -pAA was more consistent with the Temkin model, suggesting a predominantly chemisorption mechanism. After five consecutive adsorption-desorption cycles, the removal rates for MB by W@Fe 3 O 4 - g -pGMA and for Rh B by W@Fe 3 O 4 - g -pAA remained above 70%, indicating excellent recyclability and stability of the materials. This study provides valuable insights for the design of functional adsorbents and their potential application in the advanced treatment of pigment-containing wastewater.