Chromium(VI) Removal from Water by Lanthanum Hybrid Modified Activated Carbon Produced from Coconut Shells

Abstract

Cr(VI) is considered to be the most hazardous and toxic oxidation state of chromium and hence the development of effective removal technologies, able to provide water with Cr(VI) below the drinking water limits (US EPA 100 μg/L, European Commission 50 μg/L, which will be reduced to 25 by 2036) is a very important issue in water treatment. This study aimed at examining the performance of activated carbon produced from coconut shells, modified by lanthanum chloride, for Cr(VI) removal from waters. The structure of the formed material (COC-AC-La) was characterized by the application of BET, FTIR and SEM techniques. The effect of the adsorbent’s dosage, pH value, contact time, initial Cr(VI) concentration and water matrix was examined with respect to Cr(VI) removal. The results indicated that the maximum Cr(VI) removal was observed at pH 5; 4 h contact time and 0.2 g/L of adsorbent’s dosage was adequate to reduce Cr(VI) from 100 μg/L to below 25 μg/L. Freundlich isotherm and pseudo-second order kinetic models fitted the experimental data sufficiently. The maximum adsorption capacity achieved was 6.3 μg/g at pH 5. At this pH value, the removal percentage of Cr(VI) reached 95% for an initial Cr(VI) concertation of 30 μg/L. At pH 7 the corresponding efficiency was roughly 60%, resulting in residual Cr(VI) concentrations below the anticipated drinking water limit of 25 μg/L of total chromium, when the initial Cr(VI) concentration was 50 μg/L. Consecutive adsorption and regeneration studies were conducted using 0.01 M of NaOH as an eluent to evaluate the reusability of the adsorbents, Results showed 20% decrease of adsorption capacity after 5 regeneration cycles of operation.

Zeolite A powder and beads from sugarcane bagasse fly ash modified with iron(III) oxide-hydroxide for lead adsorption

“…Especially, wastes from agriculture, industry, and food have been popularly used for eliminating both cationic and anionic heavy metals. For agriculture wastes, corncob, rice husk, peanut shell, coconut shell, and sugarcane bagasse were used for removing lead (Pb), nickel (Ni), copper (Cu), chromium (Cr), and arsenic (As) in wastewater [5][6][7][8][9][10] . The peels of potato, banana, and lemon are used as food waste adsorbents for lead removal [11][12][13] .…”

Synthesis, Characterization, and Application of Magnetized Lanthanum (III)-Based Metal-Organic Framework for the Organic Dye Removal from Water

“…(5) and Eq. (6), respectively [60, 61]. (5) ln q e − q t = ln q e − k 1 t , (6) t q t = 1 k 2 q e 2 + t q e , where k 1 and k 2 refer to the pseudo 1 st order and pseudo 2 nd order rate constants with the units (min -1 ) and (g mg -1 min -1 ), respectively.…”

Comparison of Modified Peels: Natural Peels or Peels-Based Activated Carbons for the Removal of Several Pollutants Found in Wastewaters

“…Thus, researchers have studied other sources of adsorbents, such as agricultural wastes, used as natural adsorbents [21], that offer an economical and sustainable solution for several pollutants found in wastewater [22]. Examples of these agricultural wastes are some shells [23], roots [24], fruit peels [25][26][27], etc. Particularly, banana peels in powder form were examined as adsorbents for removing MB dye and pesticides, such as glyphosate and atrazine [28], or chlorpyrifos by lemon peels [29], from water.…”