Title

Optimization of the adsorption of copper, lead and nickel from aqueous solution using chitosan-coated bentonite beads in a fixed bed adsorption column

Date of Publication

2016

Document Type

Master's Thesis

Degree Name

Master of Science in Chemical Engineering

College

Gokongwei College of Engineering

Department/Unit

Chemical Engineering

Thesis Adviser

Susan A. Roces
Nathaniel P. Dugos
Meng Wei Wan

Defense Panel Member

Vergel C. Bungay
Carl Renan E. Estrellan
Lawrence P. Belo
Nathaniel P. Dugos
Jonathan R. Dungca

Abstract/Summary

Heavy metal contamination in groundwater poses a big threat to our ecosystem as it eventually pollutes surface water and is difficult and expensive to treat. A rising inexpensive and energy efficient treatment method is the use of permeable reactive barriers (PRB), an in-situ decontamination method. Chitosan-coated bentonite (CCB) is a capable reactive media for PRB. Chitosan is deacytelated chitin which contains amino (NH2) and hydroxyl (OH) groups that are capable of heavy metal recovery. Chitosan was coated on bentonite clay to reduce the cost, form a stable adsorbent and maximize the surface area for adsorption.

This study looked into the competitive adsorption of a ternary system of copper (II), lead (II) and nickel (II) using a fixed-bed adsorption column with CCB as the adsorbent. The effect of the initial concentration and flow rate of the metal solution on the adsorption process were analyzed and optimized using a central composite design of experiment.

Results showed that, of the three heavy metals, Pb(II) had a greatest affinity to the adsorbent followed by Cu(II) then Ni(II). It was also found out that the adsorption capacity was directly proportional to the influent concentration and indirectly proportional with the linear velocity. The optimal parameters for adsorption were found to be at 0.21 cm / min and 298.88 ppm influent concentration, obtaining average adsorption capacities of 9.398 mg Cu / g CCB, 12.220 mg Pb / g CCB and 7.822 mg Ni / g CCB. Compared to the predicted values from optimization, the percentage differences obtained were less than 3.32%.

The results from the adsorption experiments were also fitted with the Adams-Bohart, Thomas and Yoon Nelson Adsorption Models. The kinetic constants, kAB, kTH and kYN, were observed to increase with the increase in the linear velocity and initial concentration. The saturation concentration (NO) from the Adams-Bohart model and theoretical uptake capacity (qO) from the Thomas model decreased with the increase in linear velocity and increased with the increase in initial concentration. The Adams-Bohart model was sufficient to fit the initial part of the breakthrough curve up to 50% normalized effluent concentration while the Thomas and Yoon-Nelson models provided a good model for the adsorption data with r2 > 0.818.

Abstract Format

html

Language

English

Format

Electronic

Accession Number

CDTG006944

Shelf Location

Archives, The Learning Commons, 12F Henry Sy Sr. Hall

Physical Description

1 computer disc ; 4 3/4 in.

Keywords

Permeable reactive barriers; Water--Purification; Heavy metals

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