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Research Article |

Defluoridation of Groundwater by Activated Carbon Derived from Water Hyacinth (Pontederia crassipes) by Phosphoric Acid Activation

Elevated concentration of fluoride in groundwater poses serious health concerns in communities that depend on the groundwater for their drinking water. Efforts to develop appropriate defluoridation techniques have experienced challenges such as low efficiency, unaffordability, skill shortage, and cultural perceptions. This study evaluated the use of water hyacinth-derived activated carbon as an indigenous, environment-friendly, and socio-economically acceptable alternative technique for defluoridation. Dried water hyacinth stems were impregnated with concentrated phosphoric acid to three times their weight, and then calcinated in a muffle furnace by increasing the temperature at a rate of 5°C /min up to 600°C. The produced WHAC was characterized by scanning electron microscopy (SEM), proximate analysis and Fourier transform infrared (FT-IR) spectroscopy. Batch experiments determined effects of pH, contact time and adsorbent dosage on defluoridation efficiency. The results revealed a bulk density of 0.123 g/cm3, ash content 8.9% and fixed carbon content 66.7%. These characteristics were comparable to those of selected commercial activated carbons (CACs). The ash content was less than 10% and fixed carbon greater than 65%, suggesting high surface area and porosity that are indicative of a good quality activated carbon. The SEM revealed a rough and irregular texture illustrating high porosity. The WHAC achieved a fluoride removal efficiency of 82.6%, at pH 3 and contact time of 120 min. Fluoride adsorption by WHAC was best described by Freundlich isotherm model with a correlation factor (R2) of 0.952 and an adsorption intensity (n) of 0.285 that indicated heterogeneity of the WHAC. The adsorption was described by pseudo-second order kinetic model with a correlation factor (R2) of 0.999 and comparable experimental and theoretical adsorption capacities of 0.4608 and 0.4656, respectively, which suggested chemisorption adsorption of fluoride onto WHAC.

Defluoridation, Activated Carbon, Groundwater, Water Hyacinth, Adsorption, Isotherm

APA Style

Mugambi Muchunku, E., Kuria Ndiba, P., Auma Omondi, E. (2023). Defluoridation of Groundwater by Activated Carbon Derived from Water Hyacinth (Pontederia crassipes) by Phosphoric Acid Activation. American Journal of Water Science and Engineering, 9(4), 97-107.

ACS Style

Mugambi Muchunku, E.; Kuria Ndiba, P.; Auma Omondi, E. Defluoridation of Groundwater by Activated Carbon Derived from Water Hyacinth (Pontederia crassipes) by Phosphoric Acid Activation. Am. J. Water Sci. Eng. 2023, 9(4), 97-107. doi: 10.11648/j.ajwse.20230904.12

AMA Style

Mugambi Muchunku E, Kuria Ndiba P, Auma Omondi E. Defluoridation of Groundwater by Activated Carbon Derived from Water Hyacinth (Pontederia crassipes) by Phosphoric Acid Activation. Am J Water Sci Eng. 2023;9(4):97-107. doi: 10.11648/j.ajwse.20230904.12

Copyright © 2023 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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