Efficacy of modified distillation sludge of rose (Rosa centifolia) petals for lead(II) and zinc(II) removal from aqueous solutions

Removal of lead(II) and zinc(II) from aqueous solutions was studied using chemically modified distillation sludge of rose (Rosa centifolia) petals by pretreatment with NaOH, Ca(OH)2, Al(OH)3, C6H6, C6H5CHO and HgCl2. The adsorption capacity of biomass was found to be significantly improved. NaOH pretreated biomass showed remarkable increase in sorption capacity. Maximum adsorption of both metal ions was observed at pH 5. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. The overall adsorption process was best described by pseudo second order kinetics. The thermodynamic assessment of the metal ion-Rosa centifolia biomass system indicated the feasibility and spontaneous nature of the process and ΔG° was evaluated as ranging from −26.9501 to −31.652 KJ mol−1 and −24.1905 to −29.8923 KJ mol−1 for lead(II) and zinc(II) sorption, respectively, in the concentration range 10-640 mgL−1. Distribution coefficient (D) showed that the concentration of metal ions at the sorbent-water interface is higher than the concentration in the continuous aqueous phase. Maximum adsorption capacity of biomass tends to be in the order Pb(II) (87.74 mgg−1) > Zn(II) (73.8 mg g−1) by NaOH pretreated biomass.