Sequestration of crystal violet dye from wastewater using low-cost coconut husk as a potential adsorbent

Current study explores the effectiveness of coconut husk for crystal violet dye sequestration employing a batch experimental setup. Characterization of adsorbent was carried out via FTIR, and SEM techniques and results confirmed the involvement of OMe, COC and hydroxyl functional groups in dye uptake and rough, porous nature of adsorbent and after adsorption dye molecules colonized these holes resulting in dye exclusion. Effects of various adsorption parameters such as pH, adsorbent dose, contact time, initial dye concentration, and temperature of solution were studied. Crystal violet adsorption on coconut husk was highly pH-dependent, with maximum removal occurring at basic pH. Maximum removal of dye i.e., 81% takes place at optimized conditions. Kinetic data was analyzed by pseudo-first, pseudo second order and intra-particle diffusion model. Results showed that pseudo second order kinetic model best described adsorption of crystal violet onto coconut husk. Langmuir, Freundlich, and D-R adsorption isotherms were also used to test their appropriateness to experimental data and Freundlich isotherm fits best to data. Thermodynamic parameters showed that current process was spontaneous, endothermic in nature with continuous decrease in entropy. Established practice is 79% applicable with tap water and in acidic medium nearly 80% of adsorbent was recovered confirming the effectiveness and appropriateness of coconut husk for crystal violet dye exclusion from wastewater.

Automated summary

This study explores the effectiveness of coconut husk for crystal violet dye sequestration, with maximum removal of 81% occurring at optimized conditions. The rough and porous nature of coconut husk, along with specific functional groups, are found to be responsible for the adsorption of dye.