Efficiency of watermelon rinds, neem seeds and neem leaves as adsorbents in wastewater treatment

The study evaluates the efficiency of some natural materials as low-cost adsorbents in waste water treatment. Watermelon rind, neem leaves and neem seeds were obtained from Federal College of Education, Katsina, while the adsorbate samples are liquid effluents obtained from Katsina Youth Craft Village(KYCV), and Congo Red and Methyl orange dyes purchased from Chemical stores. Adsorption experiments were conducted at optimal conditions (10 ppm dye concentration, 0.6g adsorbent dosage, 333K temperature and 45 minutes of agitation time).  The adsorbents were characterized using Fourier Transform Infrared Spectroscopy(FTIR) and Scanning Electron Microscopy (SEM) before and after treatment to assess changes in surface morphology and functional groups. The watermelon rind (WR) had the highest percentage removal for all the samples, Congo red dye (92.5%), Methyl orange (78.3%) and the industrial effluent (83.1%). Neem leaves (NL), followed with a percentage removal of 88.1% for Congo red, 74.2% for methyl orange and 80% for the industrial dye effluent. Neem seeds had the lowest percentage removal values, 84.7% for Congo red, 71.4% for Methyl orange and 76.5% for the industrial dye effluent.  All the adsorbents had the highest percentage removal value in Congo red, followed by the industrial dye effluent from KYCV. Comparison using ANOVA revealed a significant difference in the adsorptions of the three adsorbents. The findings highlight the potential of watermelon rind, neem seed, and neem leaves as alternatives for treating dye-contaminated wastewater, especially under optimal conditions. The FTIR and SEM analyses confirmed the involvement of functional groups and surface modifications during the adsorption process.