Disinfection of water with new chitosan-modified hybrid clay composite adsorbent

Emmanuel I Unuabonah; Adewale Adewuyi; Matthew O Kolawole; Martins O Omorogie; Olalekan C Olatunde; Scott O Fayemi; Christina Günter; Chukwunonso P Okoli; Foluso O Agunbiade; Andreas Taubert

doi:10.1016/j.heliyon.2017.e00379

Disinfection of water with new chitosan-modified hybrid clay composite adsorbent

Heliyon. 2017 Aug 30;3(8):e00379. doi: 10.1016/j.heliyon.2017.e00379. eCollection 2017 Aug.

Authors

Affiliations

¹ Environmental & Chemical Processes Research Laboratory, Department of Chemical Sciences, Redeemer's University, P.M.B 230, Ede, Osun State, Nigeria.
² Department of Microbiology, University of Ilorin, Ilorin, Kwara State, Nigeria.
³ Department of Biological Sciences, Redeemer's University, P.M.B 230, Ede, Osun State, Nigeria.
⁴ Department of Earth and Environmental Science, University of Potsdam, D-14476 Potsdam, Germany.
⁵ Adsorption & Catalysis Research Laboratory, Department of Chemistry, Vaal University of Technology, Private Bag X021, Andries Potgieter Boulevard, Vanderbijlpark, 1900, South Africa.
⁶ Analytical/Environmental Chemistry Unit, Department of Chemistry/Biochemistry, Federal University Ndufu-Alike Ikwo, Ebonyi State, Nigeria.
⁷ Department of Chemistry, Faculty of Science, University of Lagos, Akoka, Lagos, Nigeria.
⁸ Institute of Chemistry, University of Potsdam, D-14476 Potsdam, Germany.

Abstract

Hybrid clay composites were prepared from Kaolinite clay and Carica papaya seeds via modification with chitosan, Alum, NaOH, and ZnCl₂ in different ratios, using solvothermal and surface modification techniques. Several composite adsorbents were prepared, and the most efficient of them for the removal of gram negative enteric bacteria was the hybrid clay composite that was surface-modified with chitosan, Ch-nHYCA _1:5 (Chitosan: nHYCA = 1:5). This composite adsorbent had a maximum adsorption removal value of 4.07 × 10⁶ cfu/mL for V. cholerae after 120 min, 1.95 × 10⁶ cfu/mL for E. coli after ∼180 min and 3.25 × 10⁶ cfu/mL for S. typhi after 270 min. The Brouers-Sotolongo model was found to better predict the maximum adsorption capacity (q_max ) of Ch-nHYCA_1:5 composite adsorbent for the removal of E. coli with a q_max of 103.07 mg/g (7.93 × 10⁷ cfu/mL) and V. cholerae with a q_max of 154.18 mg/g (1.19 × 10⁸ cfu/mL) while the Sips model best described S. typhi adsorption by Ch-nHYCA _1:5 composite with an estimated q_max of 83.65 mg/g (6.43 × 10⁷ cfu/mL). These efficiencies do far exceed the alert/action levels of ca. 500 cfu/mL in drinking water for these bacteria. The simplicity of the composite preparation process and the availability of raw materials used for its preparation underscore the potential of this low-cost chitosan-modified composite adsorbent (Ch-nHYCA _1:5 ) for water treatment.

Keywords: Environmental science; Materials science; Physical chemistry.