Characterization of a low-cost adsorbent derived from agro-waste for ranitidine removal

• Main Authors: Sutapa Das, Vaibhav V. Goud
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2020-01-01
• Series: Materials Science for Energy Technologies
• Subjects: Slow pyrolysis; Alkali-activated; Bio-char; Ranitidine; Pharmaceutical pollutant; Drug adsorption
• Online Access: http://www.sciencedirect.com/science/article/pii/S258929912030063X

Employing sustainable techniques that utilize waste resources for the generation of valuable products are pivotal towards establishing economically-sound technologies. Moreover, directing these techniques towards creating entities that aid in alleviating environmental pollution concerns are highly desirable. Rice husks (RH) are abundantly available biomasses that are usually destroyed via inefficient means. Their utilization via thermochemical processes such as pyrolysis, yields fruitful, high-utility products like bio-char and bio-oil. Bio-char presents ideal platforms for developing highly-porous organic adsorbents. This work utilizes slow pyrolysis method for converting RH to bio-char under various temperatures in presence of a CO2 environment. Utilization of CO2 influences the textural and chemical nature of the developed bio-char and its deployment also lends an environmentally-conscious facet to this work, as it helps lower the overall carbon-footprint. As-prepared bio-char was activated in presence of an alkali that enhanced its overall surface area to 440 m2/g. Activated bio-char was utilized as an adsorbent for removal of commonly-found pharmaceutical pollutant, Ranitidine. Different parametric studies such as variation in pH, adsorbent dosage and pyrolysis temperature, were performed to understand their effect on adsorption capacity of prepared adsorbents. Adsorption of 50 ppm ranitidine on the activated bio-char at pH 9, resulted in the removal of 88.3% reactant, when 100 mg adsorbent dosage was provided. Activated bio-char displayed a maximum adsorption capacity of 65.8 mg/g under those conditions. Adsorption kinetics followed a pseudo-second order pathway while the adsorption isotherm could be described by the Langmuir model.