Utilization of corn fibers and luffa peels for extraction of pollutants from water

• Corn fibers and luffa peels are efficient adsorbents for removal of dyes and toxic metal ions from water.
• Surface functional groups such as –OH and –COOH on the adsorbents are responsible for extraction.
• Biosorbents show preferential adsorption towards cationic species.

Corn fibers and luffa peels were evaluated for removing toxic heavy metal ions and dissolved organic dyes from water. Fresh peels were pretreated to remove all soluble components before using them for extraction studies. Presence of –OH and –CO2H functional groups on the surface of the peels and rough morphologies were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy investigations, respectively. Corn fibers and luffa peels showed maximum extraction efficiencies within the pH range of 4–10 and adsorption reached a steady state within 2–3 h. Prewashed corn fibers and luffa peals extracted 159 mg g−1 and 90 mg g−1 of alcian blue, 70 mg g−1 and 124 mg g−1 of methylene blue, 50 mg g−1 and 108 mg g−1 of neutral red as well as 35 mg g−1 and 40 mg g−1 of coomassie brilliant blue from water, respectively. Both materials did not show significant extraction affinity towards heavy metal ions such as Pb2+ (1 mg g−1), Ni2+ (4 mg g−1 for corn fiber and 12 mg g−1 for luffa peels), and chromate (3 mg g−1 for corn fibers and 6 mg g−1 for luffa peels) ions from water. The Langmuir and Freundlich isotherms were used to understand the adsorption process on the surface of the adsorbents. Langmuir isotherm model yielded the best fit for the data obtained in the study, indicating a monolayer adsorption of pollutants on the adsorbent surface. Both adsorbents can be regenerated at acidic pH and could be reused for up to five cycles without significant loss of efficiency. Our experimental results suggest that both natural materials are effective towards removing dissolved dyes from water.

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