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Elimination of Hexavalent Chromium Ions in Water Using a Manganese-Coated Pumice Adsorbent

Lestari Puji, Purwiandono Gani, Pramayshela Shike, Siswoyo Eko

Journal of Ecological Engineering

2024

Vol. 25, nr 1

229--235

A natural pumice stone stone coated with manganese (Mn) has been prepared and utilized to remove hexavalent chromium (Cr(VI)) ions in water via adsorption process. Prior to the application, the natural pumice was ground, sieved, and immerse in a dilute HCl solution. The coating of Mn on the acid-activated pumice was carried out by soaking the powder in 0.5 M Mn(NO3)2 solution for 72 h. The characterisation of the produced pumice adsorbent was performed with scanning electron microscopy and fourier-transform infrared spectroscopy instruments. The adsorption of Cr(VI) onto Mn-coated pumices was optimum at pH 3. Both the Langmuir and Freundlich isotherm models could be used to describe the adsorption process. The rate of adsorption followed the model for pseudo- second-order kinetics. The maximum adsorption capacity of Mn-coated pumice towards Cr(VI) ions was 1.94 mg/g.

Comparison of Two Biosorbent Beads for Methylene Blue Discoloration in Water

Purwiandono Gani, Lestari Puji

Journal of Ecological Engineering

2023

Vol. 24, nr 8

137--145

In this study, alginate-encapsulated biosorbents have been prepared from agricultural wastes viz. peanut shells and rice husks. Biosorbents in this study were referred as En-PS and En-RH for the adsorbents prepared from peanut shells and rice husks, respectively. The characteristics of the adsorbents were thoroughly investigated using scanning electron microscope, X-ray diffractometer, surface area analyzer, and Fourier-transform infrared spectrophotometer instruments. The prepared biosorbents were used as adsorbents for cationic methylene blue (MB) dye in water. The encapsulation process using sodium alginate simplified the separation of adsorbent from the water after the adsorption process. The adsorptions of MB onto both adsorbents followed the pseudo-second order model and fitted both Langmuir and Freundlich isotherm models. Thermodynamic studies revealed that the adsorption of MB onto En-PS and En-RH was a spontaneous and endothermic process with the ΔG° reaction of -1.694 and -2.028 kJ/mol at the room temperature, respectively. Biosorbents could be used in the adsorption-desorption process for up to 3 cycles.