TREATMENT OF WASTEWATER WITH ADSORBENTS MADE FROM NORTH CAROLINA AGRICULTURAL BY-PRODUCTS

OBJECTIVES: The objective of this project is to develop adsorbents with high adsorption capacity and high thermal and hydrodynamic stability from low cost, high volume North Carolina agricultural by-products such as peanut shells, corncobs and soybean hulls. The adsorbents made from these by-products will be specifically designed to remove select toxic metals, such as cadmium, copper, lead, nickel and zinc, commonly found in wastewater effluent. Adsorbents would be targeted for use in both industrial and municipal treatment systems with the intention of replacing existing, higher priced commercial adsorbents currently in use.

APPROACH: Peanut shells, corncobs, and soybean hulls will undergoing physical/chemical modification to increase adsorption capacity and efficiency and enhance thermal and hydrodynamic stability. Modification methods will include, for example, treatment with sodium hydroxide or exposure to high temperature pyrolysis followed by activation and oxidation in order to produce carbonaceous material. Batch and column experiments will be carried out to evaluate both non-pyrolyzed and pyrolyzed adsorbents. Their effectiveness as adsorbents will be evaluated and their stability will be determined by quantifying total and free metal concentrations using Inductively Coupled Plasma (ICP) spectrometry. Adsorption capacity of the non-pyrolyzed and pyrolyzed adsorbents will be measured as a function of pH and temperature.

PROGRESS: 1995/09 TO 1999/08

Corncobs were modified via washing and subsequent acid treatment. The effect of 3 washes, water wash,base wash ( 0.1 N NaOH) and no wash and 3 acid treatments, 0.6M citric acid, 0.6M phosphoric acid and no acid treatment on selected metal adsorption by modified corncobs were studied. The duplicate samples were prepared using a 3x3 factorial design. The metal adsorption efficiency was compared with the adsorption efficiency of commercial resins namely, Duolite GT-73 (D-73), Amberlite IRC-718 (A-718), Amberlite-200 (A-200), and Carboxymethyl Cellulose (CC). The acid treated samples showed statistically the same adsorption efficiency as D-73 for Cd, Cu, Ni, and Zn and higher efficiency than CC for Ni and Zn.The adsorption efficiency of D-73 for Cd, Cu, Ni Pb and Zn, was 0.49. 0.70, 0.54, 1.2, and 0.54 mmoles/g (dry wt.), respectively. For mixed metals, the same samples had statistically the same adsorption as D-73 for Cd and Cu. The chemically modified corncobs could be promising adsorbents for selected metals.

IMPACT: 1995/09 TO 1999/08

This research could lead to the development of adsorbents from agricultural by-products such as corncobs and peanut shells.

PUBLICATIONS: 1995/09 TO 1999/08

Wafwoyo, W., Chung W. Seo and Wayne Marshall. 1999. Utilization of peanut shells as adsorbents for selected metals, J. Chem Technol and Biotechnol. 74:1117-1121.

PROJ NO: NCX-9503600 AGENCY: CSRS NC.X
PROJ TYPE: SPECIAL GRANT PROJ. STATUS: TERMINATED
CONTRACT/GRANT/AGREEMENT NO: 95-38814-1729
START: 01 SEP 1995 TERM: 31 AUG 1999 FY: 1999 GRANT YR: 1995

INVESTIGATOR: Seo, C. W.; Purcell, R.; Schimmel, K.

PERFORMING INSTITUTION:
HUMAN ENVIRONMENT & FAMILY SCI
NORTH CAROLINA A&T STATE UNIV
GREENSBORO, NORTH CAROLINA 27411