커피찌꺼기로 지지된 나노영가철을 이용한 폐수 중 납과 카드뮴 흡착

• Park, Man Ho (Department of Civil & Environmental Engineering, College of Engineering, Seoul National University) ;
• Lee, Garyoung (Department of Civil & Environmental Engineering, College of Engineering, Seoul National University) ;
• Park, Hyonsu (School of Chemical & Biological Engineering, College of Engineering, Seoul National University) ;
• Jeong, Sangjae (Institute of Construction and Environmental Engineering, Seoul National University) ;
• Kim, Jae Young (Department of Civil & Environmental Engineering, College of Engineering, Seoul National University)
• 박만호 (서울대학교 공과대학 건설환경공학부) ;
• 이가령 (서울대학교 공과대학 건설환경공학부) ;
• 박현수 (서울대학교 공과대학 화학생물공학부) ;
• 정상재 (서울대학교 건설환경종합연구소) ;
• 김재영 (서울대학교 공과대학 건설환경공학부)
Nano zero valent iron (NZVI) is an emerging adsorbent for heavy metal removal with its high reactivity and reduction potential. However, NZVI tends to aggregate to bigger particles, thus surface area and reactivity could be decreased in applications. In this study, NZVI is synthesized while attached on coffee ground to prevent agglomeration. Then batch adsorption tests for $Pb^{2+}$ and $Cd^{2+}$ in wastewater were studied. Adsorption isotherm under pH 6 and $20^{\circ}C$ revealed that maximum adsorption capacity from the Langmuir model was 814.95 mg/g and 196.06 mg/g for $Pb^{2+}$ and $Cd^{2+}$ respectively. Based on mechanism of removing $Pb^{2+}$ involves reduction, adsorption isotherm did not fit well in experiments data. Time to reach equilibrium was 1 hour and 8 hours for $Pb^{2+}$ and $Cd^{2+}$, respectively. Pseudo 2nd order kinetic model explain well kinetics of heavy metal adsorption, thus adsorption is likely to be chemi-sorption. According to the mass transfer mechanism study, 80% of $Pb^{2+}$ and 60% of $Cd^{2+}$ were transported rapidly by surface diffusion and residuals are transported by interparticle diffusion. High adsorption capactiy for $Pb^{2+}$ and $Cd^{2+}$ would be related with suppression of aggregation, hence NZVI-coffee ground showed the outstanding potential on industrial wastewater treatment facilities with high concentration of heavy metals.