칼슘 이온에 의해 젤화되는 알지네이트를 내부가 고상인 비드와 내부가 액상인 캡슐 형태로 각각 만들어 납이온 흡착 특성을 비교하여 보았다. 흡착 키네틱과 흡착 등온선 분석을 통해 칼슘-알지네이트 비드와 캡슐의 흡착 특성 차이를 pH 및 경화 시간에 따른 변화, 흡착시 칼슘 이온 방출량의 모니터링을 통해 검토하였다. 비드와 캡슐의 구조적 차이에 상관없이 두 흡착제 모두 표면착화(surface complexation)와 이온교환(ion exchange) 메커니즘에 의해 납 이온을 흡착하였고, 흡착량에 상관없이 두 메커니즘 간의 비율은 유사하였다. 납이온 흡착에 대한 pH 의존성은 비드와 캡슐이 유사하였으며, 이는 두 흡착제에 존재하는 표면 작용기가 유사함을 의미한다. 반면에 흡착 키네틱 분석에서는 캡슐에 비해 비드에서의 납이온 흡착 속도가 느렸으며, 흡착 등온선 분석에서 얻은 납이온의 최대 흡착량(Qmax)은 알지네 이트 비드가 캡슐의 약 49% 정도로 나타났다. 이러한 납이온 흡착 거동의 차이는 비드와 캡슐 간의 구조적 차이에 기인한 것으로, 알지네이트 비드는 확산 저항에 의해 상대적으로 느린 흡착 속도 및 단위 무게당 적은 흡착량을 보이는 것으로 판단된다.

The adsorption behavior of Pb2+ was compared between calcium alginate beads and capsules, which have different structures of alginate-gel core beads and liquid core alginate-membrane capsules, respectively. In terms of adsorption kinetics and isotherms, adsorption characteristics depending on pH and hardening time were compared for both adsorbents and also released calcium ion during the adsorption process was monitored. The adsorption of Pb2+ on both adsorbents was caused by surface complexation and ion exchange mechanisms, both of which have similar effects on adsorption process regardless of the amount of adsorbed Pb2+. The dependence of Pb2+ adsorption upon pH was also similar for both adsorbents indicating the existence of similar functional groups on the surface of adsorbents. However, a different Pb2+ adsorption behavior was observed considering the adsorption kinetics. The adsorption kinetic of Pb2+ on alginate beads was slower than on alginate capsules and the maximum adsorption loading (Qmax) onto alginate beads was also less than onto alginate capsules by 49%. This drawback of alginate beads compared to capsules were ascribed to a diffusion limitation due to solid gel-core structure of alginate beads.

Adsorbent Alginate beads Alginate Capsules Pb2+ Adsorption

Jang LK, Nguyen D, Geesey GG, Water Res., 33(12), 2817 (1999)
Chen D, Lewandowski Z, Roe F, Surapaneni P, Biotechnol. Bioeng., 41(6), 755 (1993)
Pandey AK, Pandey SD, Misra V, Devi S, J. Hazard. Mater., B98(1-3), 177 (2003)
Shilpa A, Agrawal SS, Ray AR, J. Macromol. Sci. Part C., 43(2), 187 (2003)
Xue HB, Stumm W, Sigg L, Water Res., 22(7), 917 (1988)
Cirst RH, Martin JR, Carr D, Watson JR, Clarke HJ, Crist DR, Environ. Sci. Technol., 28(11), 1859 (1994)
Konishi Y, Asai S, Shimaoka J, Miyata M, Kawamura T, Ind. Eng. Chem. Res., 31(10), 2303 (1992)
Lazaro N, Sevilla AL, Morales S, Marques AM, Water Res., 37(9), 2118 (2003)
Chen J, Tendeyong F, Yiacoumi S, Environ. Sci. Technol., 31(5), 1433 (1997)
Yoo IK, Seong GH, Chang HN, Park JK, Enzyme Microb. Technol., 19(6), 428 (1996)
Chang HN, Seong GH, Yoo IK, Park JK, Seo JH, Biotechnol. Bioeng., 51(2), 157 (1996)
Koyama K, Seki M, J. Biosci. Bioeng., 98(2), 114 (2004)
Blandino A, Macias M, Cantero D, J. Biosci. Bioeng., 88(6), 686 (1999)
Chai Y, Mei LH, Wu GL, Lin DQ, Yao SJ, Biotechnol. Bioeng., 87(2), 228 (2004)
Cellesi F, Weber W, Fussenegger M, Hubbell JA, Tirelli N, Biotechnol. Bioeng., 88(6), 740 (2004)
Joen C, Holl WH, Water Res., 37, 4770 (2003)
Shin EW, Rowell RM, Chemosphere, 60(8), 1054 (2005)
Park HG, Chae MY, J. Chem. Technol. Biotechnol., 79(10), 1080 (2004)
Crist RH, Martin RJ, Joseph C, Environ. Sci. Technol., 30(8), 2456 (1996)
Crist RH, Oberholser K, McQarrity J, Crist DR, Johnson JK, Brittsan J, Environ. Sci. Technol., 26(3), 496 (1992)
Shin EW, Karthikeyan KG, Tshabalala MA, Bioresour. Technol., 98(3), 588 (2007)
Davis TA, Mucci A, Volesky B, Water Res., 37(18), 4311 (2003)