Investigating the efficiency of pistachio pulp biomass and the produced biochar at two different temperatures in removing cadmium from aqueous solution

Considering the environmental problems caused by heavy metals in surface and underground water, surface adsorption can be considered as a promising alternative to reduce heavy metal ions in water resources. In this study, cadmium absorption by pistachio pulp biomass and their produced biochars at 300 and 500 0C in 1401-1402 at Shahid Bahonar University of Kerman was investigated. The properties of biomass and the produced biochars were determined. The effect of pH (2-7), contact time (5-1440 minutes) and different initial concentrations (200-10 mg L-1) on cadmium absorption was evaluated. In addition, pseudo-first-order and pseudo-second-order kinetic models as well as Freundlich and Langmuir isotherm models were evaluated. The obtained results showed that the percentage of carbon increased and the percentage of hydrogen, nitrogen and sulfur decreased with pyrolysis of pistachio pulp biomass. SEM images showed that the surface of biochar is more irregular and rough than the biomass. Also, the optimal pH was 5 and the solution reached equilibrium in 120 minutes. Adsorption of cadmium by adsorbents showed a better fit with pseudo-second-order kinetic model and Langmuir isothermal model. The maximum cadmium absorption capacity by pistachio pulp biomass, biochar 300 and biochar 500 was 40.5, 58.2 and 72.5 mg g-1, respectively. The results of this study showed that the amount of cadmium absorption increased with the increase of pyrolysis temperature and pistachio pulp biochar has a high capacity to adsorb cadmium from aqueous solution.