This study investigates the enhanced adsorption of methylene blue (MB) dye on functionalized multi-walled carbon nanotubes (MWCNT-S). The MWCNT-S was synthesized by covalently functionalizing MWCNTs with benzenesulfonate groups, which improved their dispersibility in water and enhanced adsorption capacity. Key findings include: 1. **Synthesis and Characterization**: MWCNT-S was successfully synthesized through the Tour reaction, resulting in a stable dispersion in water with a concentration of 1.42 mg/mL. TEM, Raman spectroscopy, IR, XPS, and DLS analyses confirmed the successful functionalization and improved structure of MWCNT-S. 2. **Adsorption Kinetics**: Kinetic studies showed that MWCNT-S exhibited a faster adsorption rate compared to pristine MWCNTs and activated carbon (AC). The pseudo-second-order model best fit the adsorption data, indicating a chemical sorption process. 3. **Adsorption Isotherms**: Langmuir isotherms were used to fit the adsorption data, showing that MB adsorption was a monolayer process. The maximum adsorption capacity for MWCNT-S was 151 mg/g, significantly higher than that of pristine MWCNTs (67 mg/g). 4. **Effect of Adsorbent Dosage and Temperature**: The adsorption capacity of MWCNT-S was relatively stable with changes in adsorbent dosage and temperature, suggesting that the material's efficiency was not significantly affected by these factors. 5. **Regeneration**: The adsorbent's ability to regenerate was tested by treating it with 1 M NaCl, which resulted in a 75% regeneration capacity. This demonstrated the potential for sustainable and cost-effective water treatment through ionic exchange. 6. **Conclusion**: The functionalization of MWCNTs with benzenesulfonate groups significantly enhanced their adsorption capacity and kinetics for MB dye, making them a promising material for wastewater treatment. The ability to regenerate the adsorbent through ionic exchange offers a sustainable solution for water treatment and pollutant recovery.This study investigates the enhanced adsorption of methylene blue (MB) dye on functionalized multi-walled carbon nanotubes (MWCNT-S). The MWCNT-S was synthesized by covalently functionalizing MWCNTs with benzenesulfonate groups, which improved their dispersibility in water and enhanced adsorption capacity. Key findings include: 1. **Synthesis and Characterization**: MWCNT-S was successfully synthesized through the Tour reaction, resulting in a stable dispersion in water with a concentration of 1.42 mg/mL. TEM, Raman spectroscopy, IR, XPS, and DLS analyses confirmed the successful functionalization and improved structure of MWCNT-S. 2. **Adsorption Kinetics**: Kinetic studies showed that MWCNT-S exhibited a faster adsorption rate compared to pristine MWCNTs and activated carbon (AC). The pseudo-second-order model best fit the adsorption data, indicating a chemical sorption process. 3. **Adsorption Isotherms**: Langmuir isotherms were used to fit the adsorption data, showing that MB adsorption was a monolayer process. The maximum adsorption capacity for MWCNT-S was 151 mg/g, significantly higher than that of pristine MWCNTs (67 mg/g). 4. **Effect of Adsorbent Dosage and Temperature**: The adsorption capacity of MWCNT-S was relatively stable with changes in adsorbent dosage and temperature, suggesting that the material's efficiency was not significantly affected by these factors. 5. **Regeneration**: The adsorbent's ability to regenerate was tested by treating it with 1 M NaCl, which resulted in a 75% regeneration capacity. This demonstrated the potential for sustainable and cost-effective water treatment through ionic exchange. 6. **Conclusion**: The functionalization of MWCNTs with benzenesulfonate groups significantly enhanced their adsorption capacity and kinetics for MB dye, making them a promising material for wastewater treatment. The ability to regenerate the adsorbent through ionic exchange offers a sustainable solution for water treatment and pollutant recovery.