The study of pH and ionic strength on Pb(II) and Ni(II) sorption with AHUF adsorbent has been investigated. The AHUF was synthesized from humic acid (AH) with urea-formaldehyde (UF) and characterization by FTIR, SEM-EDX, total acidity content, and pH zero point charge (pHpzc). The study of pH and ionic strength using the batch system. The formation of AHUF was identified based on; decreases in total acidity (349.30 cmol/kg), emerging peaks at 3351, 1258, and 1049 cm-1 by FTIR, and increases of N atoms 21.06% by EDX. The results indicate the adsorption of Pb(II) and Ni(II) are strongly dependent on pH and ionic strength at pH < 6. The AHUF have a pHpzc value is 4.82 with optimum sorption on pH 5. The variations of NaCl to adsorption Pb(II) and Ni(II) caused a decrease in the value of ionic activity from 0.999 M “ 0.309 M, the amount of adsorbed will decreased.
