Application of watermelon rind as sorbent for removal of nickel and cobalt from aqueous solution

The present study describes the use of watermelon rind for the removal of Ni2 + and Co2 + ions from aqueous solution. Batch experiments were performed by varying pH, adsorbent dose, contact time, and initial metal ion concentration. Desorption and regeneration studies were performed to consider the reusability of watermelon rind. The maximum sorption capacity of watermelon rind was found to be 35.3 and 23.3 mg g− 1 for Ni2 + and Co2 + ions, respectively. Ni2 + ions showed higher affinity and adsorption rate compared with Co2 + ions under the experimental conditions. Extraction of Ni2 + and Co2 + ions was significantly affected by the presence of other metals due to competition.