발포질석을 부유체로 이용한 호소수의 인 제거를 위한 글리세롤, 철, 알루미늄 코팅 흡착제 제조 연구

Abstract

This study performed to make adsorbent for removal of phosphorous. We used the vermiculite as low-cost adsorbent. It can be expanded by several times in volume when heated rapidly and float on the water surface. Phosphorous is adsorbed on the surface of metallic oxide and has strong affinity for mineral surface. So we coated with Al and Fe oxide on the exfoliated vermiculite surface and heated after coating with glycerol and H2SO4 to produce porous carbon. Samples was characterized by instrument analyses and phenomena of phosphorous adsorption were tested using batch kinetic and adsorption tests. In batch test, raw exfoliated vermiculite did not remove phosphorus and Al+exfoliated vermiculite(43.38 %) better adsorbed than Fe+exfoliated vermiculite(4.41 %). In EDS and XRD analyses, Al constant was increased from 6.16 % to 10.21 % and presented an intense peak at 45.58o because of existence of Al. In the Langmuir isotherm models, the maximum sorption capacity(Qm) was 0.537 mg/g. In condition of different initial phosphorus concentration, it was well described by the pseudo second-order model. When initial concentration was increased from 5.3 to 40.8 mg/L, the adsorption capacity(qe) was increased from 0.035 to 0.377 mg/g. In EDS anaysis, C content of raw exfoliated vermiculite was near zero but C+exfoliated vermiculite was 62.2 %(380 ℃), 53.8 %(580 ℃), and 38.1 %(780 ℃), indicating the formation of a porous carbon layer on the surface. In TGA, weight loss between 450 and 620 ℃ was caused by carbon oxidation and C+exfoliated vermiculite heated at 380 ℃ had the highest weight loss. In the batch test of C+exfoliated vermiculite, the higher the carbon content of adsorbent surface, the greater the adsorption capacity for phosphorous. In the isotherm models, maximum sorption capacity(Qm) was 0.708(380 ℃), 0.486(580 ℃) and 0.183 mg/g(780 ℃) so, C+exfoliated vermiculite heated at 380 ℃ was the most efficient adsorbent. In condition of different initial P concentration and dosage of adsorbent, C+exfoliated vermiculite heated at 380 ℃ was well described by the pseudo second-order model. The adsorption capacity(qe) was 0.069, 0.113, 0.115, and 0.146 mg/g at initial concentrations of 5.2, 10.6, 15.4, and 20.4 mg/L, respectively. When dosage was increased from 1 g(25 g/L) to 4 g(100 g/L), qe decreased from 0.122 to 0.104 mg/g. In the respect of the economic and environment, using exfoliated vermiculite as low-cost natural minerals and glycerol as a co-product from the bio-diesel process is good to produce adsorbent for removal phosphorus. Also it can be easily removed in the small lake with a floating form.