Evaluating the ability of biosorbents to remove arsenic from water has global
significance due to the widespread availability and low cost of biosorbent
materials. In this study, the ability of coffee grounds and coconut substrate (two
previously unreported biosorbents) to remove arsenic from water was
compared against the performance of arsenic removal on rice husk (a recognized
and widely tested biosorbent). The three biosorbents were individually
screened for their ability to remove arsenite, As (III), and arsenate, As (V), from
water.
Batch reactors were employed to assess the percent removal, reaction
kinetics, adsorption capacity, and desorption of each arsenic species onto/from
biosorbents under pH buffered and non‐buffered conditions. The resulting
experimental data was statistically interpreted using analysis of variance and ttesting
of the means. The experimental results were also fit to existing kinetic
and isotherm models to provide kinetic rate constants, the maximum adsorption
capacity, and to help interpret the nature of the reactions on the biosorbent
surface.
While all three biosorbents removed arsenic with similar initial reaction
kinetics (pseudo 1st order reaction rate constant for As (III) was 0.13 hr^‐1 for all
three biosorbents and for As (V) was 0.17 hr^‐1 for coffee grounds and rice husk
and 0.15 hr^‐1 for coconut substrate), the amount of arsenite and arsenate
removed was highest for coffee grounds (84 and 91 percent, respectively), followed by
rice husk (68 and 72 percent, respectively), and then coconut substrate (26 and 24 percent,
respectively). The maximum adsorption capacity of arsenite and arsenate was
determined for coffee grounds (0.66 and 0.70 mg/g, respectively) and rice husk
(0.55 and 0.66 mg/g, respectively). While desorption was observed for both
coffee grounds and rice husk, the total amount of desorption accounted for less
than 15 percent of the total retained mass. The results of this thesis work reveal that
coffee can be used as an effective biosorbent when compared to rice husk;
however, coconut substrate is less effective than rice husk at removing As (III)
and As (V).
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-12-8784 |
| Date | 2010 December 1900 |
| Creators | Erapalli, Shreyas |
| Contributors | Boulanger, Bryan |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | application/pdf |
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