Results and Discussion Conclusions (Image adapted from Plan - PowerPoint PPT Presentation

September 16, 2016 K. H. Kang * , H. G. Kim ** , T. J. Park * and I. G. Byun * * Institute for Environmental Technology and Industry, Pusan National University ** School of Civil and Environmental Engineering, Pusan National University

Backgrounds Objective Materials and Methods Results and Discussion Conclusions

(Image adapted from Plan Washington.org ).

Zeolite Limestone Steel slag Dolomite

Ca 2+ + PO 4 3- 3- 3- PO 4 PO 4 3 PO 4 3- - PO 4 Ca 3 (PO 4 ) 2 ↓ 3- 3 PO 4 PO 4 - 3- PO 4 pH ↑ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+

Table 1. Chemical composition of the steel slag (Lee and Jang , 2004) Composit itio ion Conte ntent (%) (%) CaO aO 40.1 SiO 2 14.4 Fe 2 O 3 10.8 MgO 7.2 MnO 3.1 Al 2 O 3 2.1 TiO 2 0.8

Table 2. Conditions for batch operation Table 3. Parameters for PO 4 -P removal Value Val Par arameters rs Val Value Working vol. 300 mL pH 5, 6, 7, 8, 9, 10 and 11 25 ℃ Temperature PO 4 -P conc. 25, 125 and 250 (mg/L) Agitation speed 120 rpm Amt. of slag (g) 25, 50, 100 and 150 g Period 4 d

Fig. 1. pH variations of distilled water by steel slag according to the elution time.

Fig. 2. Comparison of the pH change between distilled water and K 2 HPO 4 solution with steel slag according to the elution time.

(A) (B) Fig. 3. SEM images of the uncoated (A) and CNT-coated (B) steel slag.

Fig. 4. Changes in the PO 4 -P concentration and pH in the K 2 HPO 4 solution with CNT-coated slag and uncoated slag.

Table 4. PO 4 -P removal efficiency according to input CNT-coated stell slag for 12 and 24 h PO PO 4 -P rem emova val CNT NT- effic iciency (%) (%) coat coated Fi Final l st steel l pH pH slag sl ag (g) (g) 12 12 h 24 24 h 25 9.0 37.1 67.4 50 8.8 50.3 84.7 100 9.4 80.1 97.2 Fig. 5. Kinetics of the PO 4 -P concentration at different 150 9.5 98.2 99.5 amount of CNT-coated steel slag (C 0 = 250 mg PO 4 -P/L).

Fig. 6. Kinetics of the PO 4 -P concentration and changes in pH at various initial PO 4 -P concentration (CNT- coated steel slag input = 50 g).

Fig. 7. Relationship between ln X and ln C e based Fig. 8. Relationship between 1/X and 1/C e based on the Freundlich isotherm equation for CNT- on the Langmuir isotherm equation for CNT- coated steel slag at 25 ℃ . coated steel slag at 25 ℃ .

Table 5. Freundlich and Langmuir isotherm constant of Table 6. Comparison of K value between CNT- CNT-coated steel slag coated steel slag and other materials Fre reundlic ich isot otherm Lang angmuir ir isot otherm rm Abso bsorbent K K (m (mg/ g/g) Reference Ref consta con tant con consta tant Tang et al., Shale 69.2 K (mg/g) 421.6 a (mg/g) 1250 2009 Tang et al., 1/n 0.33 b (mg/g) 0.47 Ironstone 29.7 2009 R 2 0.97 R 2 0.84 Kim et al., EAF-slag 29.3 2010 CN CNT- coa coated stee eel 421 421.6 This This stud udy slag