Affiliations: Environmental and Water Resources Engineering
Division, Department of Civil Engineering Indian Institute of Technology
Madras, Chennai-36
Abstract: A number of methods for heavy metal removal from waste water have
been used, but most have several disadvantages, such as continuous input of
chemicals, high cost, toxic sludge generation or incomplete metal removal. The
use of rice husk not only provides a less costly sorbent to activated carbon or
synthetic ion-exchanger as it is cheap, but also available in abundant
quantity. Various modifications on rice husk have been reported in order to
enhance sorption capacities for metal ions and other pollutants. The study
reported in this paper deals with the adsorption of heavy metals such as lead
(Pb), copper (Cu), zinc (Zn) and manganese (Mn) on the low cost adsorbents such
as Rice Husk (RH) and Phosphate treated Rice Husk (PRH) from the synthetic
solutions. Batch studies were conducted to find out the optimum dose of
adsorbent, optimal pH and contact time for individual metal solution, both with
RH and PRH. It was found that the equilibrium was attained after 30 min for Pb,
40 min for Cu and 50 min both for Zn and Mn and the maximum removal efficiency
was attained at a pH of 6 for Pb, pH of 7 for Zn, Cu and Mn for the single
metal solutions. The adsorption data could be fitted with Freundlich, Langmuir
isotherm equation to find the characteristic parameters. It was found that
linear form of Freundlich isotherm seems to produce a better model than linear
form of Langmuir equation.
Keywords: Heavy metal removal, adsorption study, batch experiments, isotherm
