chemical modification of sumac tree bark-derived activated carbon with tungsten oxide as a novel natural adsorbent for removal of heavy metals

Heavy metals are a serious global threat, and their removal from water is essential, though conventional synthetic methods have notable limitations. natural adsorbents have emerged as a promising and eco-friendly solution to this challenge. in this work, for the first time, sumac tree bark has been used as a natural adsorbent for modification. the choice of sumac is due to its abundant availability as an agricultural byproduct in iran, its high content of tannins and phenolic compounds that enhance carbonization and adsorption, and its low cost. sumac tree bark was initially carbonized at 500 °c after chemical activation with phosphoric acid (h3po4, 85%) to obtain activated carbon (acst), which was then modified with tungsten oxide (wo3) to form the wo3-acst composite. the synthesized adsorbent was applied as a low-cost, biodegradable, and efficient material for heavy metal removal, with key influencing parameters systematically evaluated.the results of ft-ir, xrd, and sem analysis confirmed the successful synthesis of wo3-acst composite. the effects of different parameters such as ph, temperature, concentration, contact time, adsorption dosage, adsorption isotherm, and adsorption kinetics of as, pb, and co were studied with the synthetic adsorbent. the results indicate that the adsorption of heavy metals onto wo₃/acst conforms to the langmuir and pseudo-second-order models, with regression coefficients exceeding 99% for as, pb, and co uptake by the wo₃/acst composite (r² > 0.99%). the synthetic adsorbent had good reproducibility of 93% in heavy metal removal for up to 5 cycles.