Optimization of process variables by response surface methodology for malachite green dye removal using lime peel activated carbon

Leather, textile, paper and pulp industries discharge large quantities of highly coloured effluent containing dyes into nearby rivers or land without any treatment because conventional treatment methods are very expensive. Small amount of dye present in water (<1 mg/L), is highly visible and consequently undesirable (Sun and Yung 2003 ). Based on the chromophore group, 20–30 different groups of dyes are pollutants; therefore, removal of color from effluents is one of the major environmental problems. Different investigations on the effectiveness of low-cost adsorbents for effluent treatment of various applications have been carried out, e.g., perlite (Dogan et al. 2000 ), wheat straw (Robinson et al. 2002 ), straw carbon (Verma and Mishra 2006 ), periwinkle shell (Bello et al. 2008 ), banana stalk (Bello et al. 2012a , b , c ), groundnut hull (Din et al. 2009 ; Bello et al. 2012b ), oil palm ash (Hasan 2008 ; Foo and Hameed 2009a ), oil palm fruit fibre (Bello 2013 ), cocoa pod husks (Bello and Ahmad 2011a ), mango peels (Bello and Ahmad 2011b ), rice husk (Foo and Hameed 2009b ; Yahaya et al. 2010a , b , 2011a , b ); Bello and Ahmad 2011c , d ), palm kernel shell (Zawani et al. 2009 ), coconut shell (Bello and Ahmad 2012b ), Imperata cylindrica leaf (Bello and Semire 2012 ), rubber seed coat (Bello and Ahmad 2012a ) and fly ash (Bello et al. 2013 ). The dye under investigation, Malachite green is used to colour silk, leather and paper. It is water-soluble, found as contaminant in industrial effluents. Clinical and experimental observations reported so far reveal that malachite green is a multi-organ toxin. Malachite green is highly cytotoxic to mammalian cells and carcinogenic to liver, thyroid and other organs in animals (Sundarrajan et al. 2000 ).