Adsorption of malachite green from aqueous solution by naoh-modified rice husk: Fixed-bed column studies

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In this work, a continuous fixed-bed adsorption study was carried out by using NaOH-modified rice husk (NMRH) as an adsorbent for the removal of malachite green (MG) from its aqueous solution. The influence of important process parameters such as initial solution pH, influent concentration of MG, feed flow rate, and bed height on breakthrough curve and breakthrough time was investigated. The breakthrough time increased with decreasing flow rate. The same effect was noted when the bed height was increased. On the other hand, the breakthrough time decreased as the inlet dye concentration was increased keeping the flow rate and bed height constant. Four different kinetic models, namely Adams–Bohart, bed depth service time bed depth service time (BDST), Thomas model, and Yoon–Nelson model were fitted to the experimental data. The Thomas model showed best fit at all experimental conditions studied. Overall, this study showed that NMRH has potential for technological application as adsorbent in dye wastewater treatment. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 633–639, 2013