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A batch sorption experiments were carried out to study the role of biosorbent and nano-particles on removal of some heavy metals from aqueous solution. The rice straw waste was used as biosorbent material( by-product of agricultural activity). In addition, Nano-Hydroxyapatite (60 nm) and nano-Zero Valent Iron (25 nm) were used as nanoparticles. The batch sorption was done using rice straw waste (RSW) with three sizes as 0.125, 0.25 and 0.5 mm with Pb 2+ and Ni 2+ with concentrations up to 28.14 and 100 mg/l, respectively. Also, the sorption experiment was conducted using nano-particles (n-HAP and n-ZVI) and phosphate rock for Pb 2+ and Ni 2+ with concentration up to 20 mg/l for Ni and 18.0 mg/l for Pb. The results indicated that RSW (0.250 mm) was best size for heavy metals removal. The rice straw waste has more ability for retention of heavy metals such as Ni and Pb according to linear and Freundlich sorption models. Also, the results indicated that maximum sorption capacity of heavy metals was occurred on Nano-Hydroxyapatite (n-HAP) for both Pb and Ni. These results may be due to the functional groups found in Nano-Hydroxyapatite. When RSW mixed with n-HAP, the results indicated maximum removal percentage of heavy metals. The removal percentage of Pb (99.70%) was more than Ni (38.25%) indicated that the ability of Pb to bind with RSW or n-HAP more than Ni. The current results are very useful in the treatment of wastewaters for the removal of heavy metals, making them suitable for agricultural purposes. The present study recommends a future studies to understand the role of nanomaterials on removal the different heavy metals under different conditions.

Two field trials were conducted in the