The biosorption potential of modified bottle gourd shell for phosphate: Equilibrium, kinetic and thermodynamic studies

Abstract

In order to preserve the environment and prevent the occurrence of eutrophication, a new quaternary ammonium biosorbent based on the bottle gourd (Lagenaria vulgaris) shell (QALVS) was prepared and characterized in the present study. The results of FTIR and elemental analyses confirmed the successful modification of the lignocellulosic biomass and showed that 15.68 mg N g-1 was incorporated as cationic –N+R3 group. The biosorbent was tested to remove phosphate from aqueous solution in batch mode. Kinetic studies indicated that the biosorption of phosphate onto QALVS can be fitted by a non-linear pseudo nth-order model (n ≈ 1) very well. The Freundlich model provided the best description of the biosorption process. The maximum phosphate biosorption capacity was 16.69 mg P g-1 for QALVS at 20°C and pH 6. Thermodynamic parameters indicate that the biosorption of phosphate by QALVS is exothermic. The anion exchange mechanism was the dominant process, in addition to physisorption. Coexisting ions exhibited a distinct effect on phosphate biosorption with the order of NO3 - > SO4 2- > Cl-. The QALVS biosorbent could be repeatedly used in phosphate biosorption with slight losses in initial biosorption capacities

Keywords

• Lagenaria vulgaris
• phosphate
• biosorption
• kinetic
• equilibrium
• thermodynamic