A Sustainable Green Approach for Efficient Capture of Strontium from Simulated Radioactive Wastewater Using Modified Biochar

The present investigation was targeted to remove radioactive strontium (Sr(II)) from synthetic solution using synthesized peanut shell activated biochar (PSABC). The biomass of peanut shells was pyrolyzed at 400 °C for 30 min and then activated with KOH. The surface area and pore volume of PSABC were estimated by BET method. Characterization of prepared PSABC was executed by BET, FTIR, SEM, and EDS analysis. The responsible functional groups for adsorption of Sr(II) onto PSABC were investigated using FTIR and the adsorption was confirmed by SEM and EDS analysis. RSM-based CCD was used to scrutinize the effective parameters. Based on the results, the maximum % removal (99.02) of Sr(II) was attained at optimum conditions, i.e., pH: 4.92, Biosorbent dosage (BD):0.039 g and initial concentration (IC):0.54 mg/L. Freundlich model gave good fit to the equilibrium data with R 2 = 0.99 and Sr(II) uptake potential predicted from Langmuir was 133.11 mg/g. Sr(II) adsorption kinetics were well correlated to pseudo-second-order model. The thermodynamic energy changes such as ∆ G °, ∆ H ° and ∆ S ° were estimated and found that the process was spontaneous and exothermic in nature. The effect of coexisting ions on Sr(II) removal by PSABC was also studied and found that at PSABC is able to adsorb 53.55% Sr(II) at a highest Ca 2+ concentration of 500 mg/L. Further, desorption study was conducted with five different desorbing solvents to estimate the ease of regeneration behavior of PSABC. Conclusively, the results revealed that PSABC is prominent and cheap biosorbent for removal of Sr (II) from aqueous medium. Article Highlights KOH activated biochar (PSABC) produced from agricultural waste was used to treat simulated radioactive wastewater. Developed biochar was characterized using FTIR, SEM, and EDS to authenticate adsorption and also to disclose adsorption mechanism. The maximum Sr(II) uptake by PSABC predicted using Freundlich model is 133.11 mg/g; kinetic and thermodynamic studies disclosed the process as feasible chemisorption. PSABC is capable of removing more than 50% of Sr(II) in the presence of a very high Ca 2+ concentration of 500 mg/L. Desorption studies revealed that after desorption, the adsorbent can be used for several cycles.