Currently, activated charcoal is used to remediate heavy metals from water, but it can be expensive. Alternatives such as rice husk-derived biochar can be used as a cost-efficient method of remediating heavy metals. This study aimed to determine the most effective particle sizes (0.149, 0.42, 0.85 mm) of rice husk biochar compared to activated charcoal. The activated carbon was chemically treated using potassium hydroxide and thermally treated at 600℃. The exposed solution was then filtered and assessed using a spectrophotometer and the Beer’s Law plot. The data was analyzed in SPSS version 28 using a One-Way ANOVA post hoc Scheffe (p<0.05). Results showed that the concentration of CuSO4 after remediation was significantly reduced (p<0.01) when implementing biochar with sieve sizes of 0.149 mm rather than activated charcoal, with average concentrations of 0.024 ± 0.0095 M and 0.0047 ± 9.54 M remaining, respectively. The 0.149 mm particle size resulted in the highest percentage removal (76 ± 9.54%) compared to the activated charcoal (6.57 ± 8.11%). The promising results displayed by rice husk-derived biochar with a particle size of 0.149 mm can be attributed to the high surface area, allowing for increased contact efficiency in remediation. The results of this study showed that rice husk-derived biochar was an efficient alternative to activated charcoal in remediating CuSO4. Future studies should consider using this material to remediate alternative pollutants, such as textile dyes, including methylene blue.

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