ABSTRACT
The possibility of adsorbing Pb(II) from solution using coir, a cheap lignocellulosic fibre, was assessed in a fixed bed column. The coir fibres were also chemically modified by covalent loading of a reactive dye, C.I. Reactive Orange 13, and used as adsorbent. Column adsorption studies were carried out at different initial Pb(II) concentrations and it was observed that the breakthrough time decreased with increase in the initial Pb(II) concentration. The column packed with dye loaded coir fibres was operated for longer duration than the one packed with unmodified coir fibres. The total Pb(II) adsorbed was also higher in a column packed with dye loaded coir fibres. The desorption level in the fixed bed column packed with coir fibres was of the order of 85%, whereas the one packed with dye loaded coir fibres was more than 90%. Both the columns were regenerated and used upto five cycles.
Subject(s)
Azo Compounds , Cellulose/chemistry , Environmental Pollution/prevention & control , Industrial Waste/prevention & control , Lead/isolation & purification , Lignin/analogs & derivatives , Nitrates/isolation & purification , Sulfuric Acid Esters , Adsorption , Lignin/chemistryABSTRACT
The potential of a lignocellulosic fibre, jute, was assessed for adsorption of heavy metal ions like Cu(II), Ni(II) and Zn(II) from their aqueous solutions. The fibre was also used as adsorbent after chemically modifying it by two different techniques viz, loading of a dye with specific structure, C.I. Reactive Orange 13, and oxidising with hydrogen peroxide. Both the modified jute fibres gave higher metal ion adsorption. Thus, the dye loaded jute fibres showed metal ion uptake values of 8.4, 5.26 and 5.95 mg/g for Cu(II), Ni(II) and Zn(II), respectively, while the corresponding values for oxidised jute fibres were 7.73, 5.57 and 8.02 mg/g, as against 4.23, 3.37 and 3.55 mg/g for unmodified jute fibres. Adsorption isotherm models indicated best fit for Langmuir model for the modified jute fibres. The adsorption values decreased with lowering of pH. The desorption efficiency, regenerative and reuse capacity of these adsorbents were also assessed for three successive adsorption-desorption cycles. The adsorptive capacity was retained only when the caustic soda regeneration is carried out as an intermediate step after desorption. Possible mechanism has been given.
