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Subject: search.filters.subject.Cadmium

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    PublicationOpen Access
    Column Study for Adsorption of Copper and Cadmium Using Activated Carbon Derived from Sewage Sludge
    (hindawi.com., 2022-03-22) Al-mahbashi, N; Kutty, S. R. M; Jagaba, A. H; Al-Nini, A; Ali, M; Saeed, A. A. H; Ghaleb, A. A. S; Rathnayake, U
    mong the water-polluting substances, heavy metals stand out due to their carcinogenic and toxic effects on the creatures and environment. This study aimed to scrutinize the effectiveness of sewage sludge-based activated carbon in the removal of copper and cadmium from aqueous solutions in column study. Detection of breakthrough curves and related parameters was conducted by varying bed depths (3, 6, and 9 cm). The solution with an initial metal concentration (IMC) of 100 ppm was pumped to the column at a flow rate of 2 mL/min. In the process of copper removal, the breakthrough points for depths 3 cm, 6 cm, and 9 cm were achieved at 10 min, 15 min, and 60 min, respectively, whereas breakthrough points of similar depths in cadmium removal process were achieved at 5 min, 10 min, and 30 min, respectively. Adsorption kinetics were analyzed using the Adams–Bohart, Yoon–Nelson, and Thomas kinetics models. The Adams–Bohart model described only the initial part of breakthrough curves. The Thomas model represented the adsorption process with coefficients of determination (R2) ranging between 0.90–0.95 for cadmium removal and 0.89–0.96 for copper removal, while the coefficients of determination of Yoon–Nelson ranged between 0.89–0.94 for cadmium and 0.95–0.97 for copper. Yoon–Nelson was fitted well with copper removal data, while removal of cadmium data was best described by the Thomas model. This study demonstrated that using sewage sludge-based activated carbon to remove heavy metals is an alternative, more cost-effective option to reach the objectives of sustainable development.
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    PublicationEmbargo
    Phytoremediation of heavy metals by calcifying macro-algae (Nitella pseudoflabellata): implications of redox insensitive end products
    (Pergamon, 2013-08-01) Gomes, P. I. A; Asaeda, T
    To evaluate the phytoremediation of heavy metals in water and understand the biochemistry of end products of calcifying macro algae (charophytes), an 84-wk laboratory experiment was conducted. Eighteen microcosms were maintained with and without plants. These were given different heavy metal treatments: no heavy metals, 0.2 mg L−1 Cr6+ and 0.01 mg L−1 Cd. Accumulation observed to be 0.06% Cr by dry weight and for Cd it was 0.02%. The bioconcentration factors were 3000 and 25 000 for Cr and Cd, respectively. Ratios of heavy metal accumulation in alkaline (i.e., calcified areas) to acidic areas of plants were 6 to 4 (for Cr) and 1 to 1 (for Cd). This elucidated an association between heavy metal accumulation and calcification. This was validated by sequential extraction of sediments. It was shown that in microcosms with plants, the heavy metals were mainly in redox insensitive and less bioavailable carbonate bound form (39–47%). This was followed by organic-bound form (23–34%). Carbonate bound end products will ensure long term storage of heavy metals and after plant senescence these will not re-enter the water column.