ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Improving Cd⁺² adsorption capacity of activated carbon by modification method: optimization with taguchi experiment design and analysis of variance

İlknur Demiral and Canan Samdan

Department of Chemical Engineering, Faculty of Engineering and Architecture, Eskişehir Osmangazi University, Eskişehir, Turkey

E-mail: idemiral@ogu.edu.tr

Received: 20 September 2021  Accepted: 4 December 2021

Abstract:

Adsorption processes are seen as simple water or industrial wastewater treatment methods that effectively remove various pollutants from an aqueous solution. This study aimed to increase the adsorption properties of activated carbon (3AC400) produced from biomass (peach stone) by making improvements and changes in the surface functional groups. HNO₃, which is very effective on activated carbons, was chosen as the modification chemical, and its effect against Cd⁺² adsorption was investigated. By grafting oxygen-containing acidic groups on the surface of activated carbons, the surface chemical properties have changed, and the Cd⁺² adsorption capacity has increased. The most effective inoculation was obtained for activated carbon with code 30NAC/90/6 after 6 h of operation at 90 °C. The Cd⁺² adsorption capacity of 30NAC/90/6 was determined to be four times the adsorption capacity of 3AC400. The Cd⁺² adsorption rate was determined to increase four times by HNO₃ oxidation. The surface area was influential on the Cd⁺² adsorption for the 3AC400 sample while the oxygen-rich active sites on the surface of 30NAC/90/6 played an important role for the 30NAC/90/6 sample. Cd⁺² adsorption results onto 3AC400 and 30NAC/90/6 the Taguchi experimental design (L9) were optimized using the orthogonal sequence. In the design, four operating parameters (temperature, adsorbent amount, initial Cd⁺² concentration and contact time) are modelled as 3 levels. The effects of control factors on Cd⁺² removal efficiency were examined by analysis of variance. According to Taguchi experimental design, the most important factors affecting Cd adsorption are temperature, amount of adsorbent and contact time, respectively. Cd⁺² adsorption studies were carried out under optimum conditions determined by Taguchi design. In the 30NAC/90/6 sample, 99% Cd⁺² removal was obtained under optimum conditions.

Graphic abstract

Keywords: HNO3 modification; Activated carbon; Characterization; Cd+2 adsorption; Taguchi design

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-02011-0

Chemical Papers 76 (4) 2193–2207 (2022)