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.

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During past decades, spectroscopic techniques find wide range of applications ranging from biological applications to the measurement of chemical composition and characterization of variety of substances i.e., polymers, nanocomposites etc. Nanocomposites are emerging and growing materials having wide variety of uses. To study the characteristic properties, characterize, and development of new materials using polymer nanocomposites, several molecular characterization techniques are available and are in use today. Principle objective of this review is to summarize the knowledge in current characterization techniques and to study the applications of fluorescence, solid-state nuclear magnetic resonance (NMR), infrared, besides Raman molecular characterization techniques for characterization of polymers, filler, and composites. Fluorescence technique did not provide detailed analysis of materials while solid-state NMR spectroscopy determine silanol hydroxyl groups at the silica exterior in addition to their interactions with polymer and polymer-filler interfacial interactions (via relaxation time). For characterization of various kinds of functional groups in polymer/ fillers, infrared spectroscopy employed. While Raman spectroscopy finds extensive applications for analysis of carbon-based materials. Novelty of this review is that till yet very few review papers have been published which briefly describe all these mentioned techniques along their applications in a very simple and an effective way.