An investigation on zinc biosorption with agar extraction waste from Gracilaria tenuistipitata

Date of Publication


Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Biochemistry

Subject Categories

Biochemistry, Biophysics, and Structural Biology


College of Science



Thesis Adviser

Nancy Lazaro Llanos

Defense Panel Member

Marissa G. Noel

Cristian Ryan A. Argamino


The continuous flow of effluents from industries into Philippine waters remains a barrier towards effective bioremediation. This poses the need to develop new methods that are cost-effective yet highly efficient in eliminating water pollutants. The study aims to determine the biosorption capacity of Gracilaria tenuistipitata waste obtained from agar extraction on Zn(II) ions. An alkali pretreatment was employed to extract agar and Fourier-transform infrared spectroscopy (FTIR) was used to characterize the product. The algal waste was then subjected to a biosorption study involving various Zn(II) standard solutions and an approximate biosorbent dosage of 0.1 g. Atomic absorption spectroscopy (AAS) and FTIR were employed to quantify and evaluate the sorption process. Equilibrium sorption data was analyzed using Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms which yielded R² values of 0.9680, 0.8103, and 0.5254, respectively. The Langmuir (K˪), Freundlich (KF), and D-R (B) constants garnered were 0.0231 L/mg. 0.9829 mg/g, and 2.159 x 10 respectively and further reveal that the adsorption of Zn(II) ions onto the algal waste is a favorable and physical process. FT-IR peaks support that the extracted gel is agar, and that functional groups involved in biosorption mainly involve carboxylic acid and slide groups, indicating than an ion-exchange process takes places in uptake of Zn(II) ions. Performing the biosorption procedure in triplicates and the inclusion of kinetic studies are highly recommended to improve and ensure the accuracy in determining biosorption capacity and optimization in future studies.

Abstract Format






Accession Number


Shelf Location

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

Physical Description

ix, 93 leaves : illustrations (some color) ; 28 cm.


Bioremediation--Philippines; Water--Purification-- Biological treatment; Water--Pollution--Philippines

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