Usage of Walnut shell granule's as a natural adsorbent for removal of Nickel from aqueous solutions

Increasing environmental pollution by heavy metals caused serious concerns due to carcinogenic properties, their biological accumulation and inseparability. Nickel was one of the most common pollutants priority in the environment that its elimination is very important. There is several methods to remove and isolation heavy metal ions from aqueous solution that the most of these methods are used in high concentrations of metals and has disadvantages such as high cost of equipment and operations, sludge production or toxic waste, energy and high space requirements. Between these methods, the process of adsorption has attracted the attention of many fans; because a simple, low-cost and effective to remove heavy metal ions in low concentrations and average. The purpose of this study is survey the efficiency of adsorption of Nickel ions from aqueous solutions by walnut shell granules.
This study was a fundamental and experimental research that adsorption process is interrupted, in laboratory conditions were examined, with an emphasis on the effects of various parameters such as pH, contact time, initial concentration of Nickel and adsorbent dosage on the adsorption efficiency. At each stage of tests were investigated; 100ml of solution containing specified initial concentration of Nickel and with the preferred level of pH(2-8), reaction time(10-30min), initial concentration(10-100mg/l) and the adsorbent dosage(0.1-1g), then the results was fit by Langmuir & Freundlich isotherm also first & second pseudo kinetics.
The results showed that the maximum efficiency of adsorption of Nickel was in the range of pH 5 to 8, adsorbent dose 0.5g/100ml and 90 minutes contact time. Moreover seen that data of adsorption followed the Langmuir isotherm with a correlation coefficient of r2=0.99 and the first pseudo kinetics (R2=0.9922) & second pseudo kinetics (R2=0.9937).
Based on the results of this study may suggest that walnut shell granule's is ideal as a natural adsorbent to remove Nickel from aqueous solutions. And it's recommenden because of the ability to adsorb up to other environmental contaminants.