Plant-Derived Biosorbents for Pollutant Removal and Carbon Nanoparticle Synthesis
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2023
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Abstract
Generally, biosorbents can be derived from animals, plants, and microbial wastes. The animal sources are fishery and animal husbandry, while plant-based biomass is forestry and agriculture. Herein, our focus is on the plant-based biosorbent for synthesizing activated biochar and hydrochar for the removal of dyes and heavy metals and the synthesis of carbon dots for metal sensing applications. Ricinus communis stem (RCS) was chemically activated with potassium carbonate (K2CO3) and heated at 300˚C to produce low-temperature Ricinus communis stem-activated biochar (RCSB). Initially, adsorption experiments were carried out with nine cationic and anionic dyes. Among these dyes, two cationic dye, malachite Green (MG) and methylene Blue (MB), shows more than 90% dye removal using RCS (92%) and RCSB (99%). The kinetics and equilibrium data were best fitted with the intra-particle diffusion kinetics model (R2=1) and the Langmuir isotherm model. Adsorption experiments were performed to evaluate the effect of pH, adsorbent dosage, contact time, initial dye concentration, stirring speed, particle size, and temperature. The thermodynamic parameters support the feasible, spontaneous, and exothermic adsorption in the temperature range of 293-323K. Desorption experiments were carried out at pH 2 with an efficiency of ~97 %. Regeneration study indicates biosorbents can be recycled in up to five cycles. The present studies suggest using RCS and RCSB has potential application as eco-friendly biosorbents for efficient removal of MG and MB dyes up to 99%.
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Supervisors: Das, Gopal and Ramesh, Aiyagari