Phosphoric acid activated <i>Areca catechu</i> as an efficient biosorbent for Cr(VI) sequestration from simulated and industrial effluent

A new biosorbent for Cr(VI) sequestration has been developed from betel nut, <i>Areca catechu</i>, waste by treating H₃PO₄ followed by carbonization to give phosphoric acid carbonized betel nut waste (PCBNW). The structural and physicochemical characteristics of investigated biosorbents were evaluated <i>via</i> functional group identification, surface analysis, elemental analysis, and X-ray diffraction measurement. The maximum biosorption potential of Cr(VI) was drastically improved from 14.00 ± 0.13 to 188.68 ± 0.20 mg/g after modification at an optimal pH of 2. The outcomes demonstrated that a certain amount of Cr(VI) was reduced to Cr(III) during the process, pointing out that the phenomenon was a chemisorption along with reduction. The PCBNW efficiently eliminated a trace amount of Cr(VI) present in the industrial wastewater, which was lower than the wastewater standard, as established by WHO (0.10 mg/L). Also, PCBNW effectively worked even when there were coexisting-ions namely, NO₃⁻, Cl⁻, CO₃²⁻, SO₄²⁻, and PO₄³⁻. Furthermore, more than 93.65 ± 3.72% of the biosorbed Cr(VI) was desorbed by a solution of 2 M NaOH. Hence, PCBNW analyzed in this research displays great potential for sequestration of Cr(VI) from adulterated water. A new biosorbent for Cr(VI) sequestration was developed from <i>Areca catechu</i> waste by H₃PO₄ activation followed by carbonization.Biosorbents were characterized using FTIR, SEM, EDX and XRD, which demonstrated the successful modification.Effect of various experimental parameters such as pH, contact time, initial Cr(VI) concentration and PCBNW dose were investigated.PCBNW showed high biosorption capacity and stability and was regenerated using a dilute alkali solution.Mechanism of Cr(VI) biosorption is inferred to be complexation, ion exchange and ionic interaction. A new biosorbent for Cr(VI) sequestration was developed from <i>Areca catechu</i> waste by H₃PO₄ activation followed by carbonization. Biosorbents were characterized using FTIR, SEM, EDX and XRD, which demonstrated the successful modification. Effect of various experimental parameters such as pH, contact time, initial Cr(VI) concentration and PCBNW dose were investigated. PCBNW showed high biosorption capacity and stability and was regenerated using a dilute alkali solution. Mechanism of Cr(VI) biosorption is inferred to be complexation, ion exchange and ionic interaction.