Research on modified blast furnace dust in demulsification: The synergistic effect of ferric oxide, hydrophobic carbon, and polysilicate

Figures & data

Table 1. Water quality comparison between actual and simulated wastewater.

Effluent type	CODCr (mg·L^−1)	pH	Oil (mg·L^−1)	Average particle size (μm)	Zeta (mV)	Type
Actual	7000–10000	7.5–8.5	930–1500	2.631–3.893	(−62.4) – (−44.9)	O/W
Simulate	7875.42	5	1172.59	3.212	−51.2

Figure 1. SEM images of the BFD at (A) 200x, (B) 400x, and (C) 10,000x magnification and corresponding spectra obtained by EDS.

Figure 2. X-ray diffraction pattern and XRF analysis of the BFD elements.

Figure 3. (a) The effect of adding different strong hydrophobic carbons (A: ZHF-R90, B: GWF-R90, and C: MWF-R90) on the COD_cr and oil removal efficiency, and water contact angle of the MBFD₁; Effect of the carbon content of the MBFD₂(b), hydrophobic carbon (GWF-R90) dosage (c), and n_(Fe)/n_(Si) of the MBFD₃ (d) on COD_cr and oil removal efficiency; (b₁) Comparison between the use of MBFD₂ (ω_(c):14.86%) and hydrophobic carbon (GWF-R90) on COD_cr and oil removal efficiency; (e) Demulsification of the MBFD before and after modification; (Experimental conditions for (b₁) and (c): hydrophobic carbon (GWF-R90) and MBFD₂ (ω_(c):14.86%): 0.8g·L⁻¹, pH:5, the stirring pattern 2)

Table 2. XRF analysis results of elements of the BFD before and after modified.

Ele. wt.%	Fe	C	Mg	Si	Ca	Al
Oxide	Fe2O3	\	MgO	SiO2	CaO	Al2O3
Before	30.27	8.86	3.85	21.19	6.50	6.64
After	39.62	13.45	2.57	19.17	4.98	5.10

Figure 4. SEM images for the MBFD (a) 400x, (b) 10,000x; SEM images of the MBFD₁(c)1000x, the MBFD₂(d)1000x and the MBFD₃(e)10000x under the optimum modification condition.

Figure 5. Fourier infrared absorption spectra of the BFD before(a) and after(b) modified; (c) MBFD after one cycle.

Table 3. Water contact angle, Zeta potential (pH:5) and Specific surface area results of the BFD before and after modified.

Index	Water contact angle (°)	Specific surface area (m^2·g^−1)	Zeta potential (mV)
Before	112.6	3.6	3–11
After	145.5	4.8	9–18

Figure 6. Effect of the initial pH(a), the BFD dosage(b), and the G^– (c) on COD_cr and oil removal efficiency of the modified BFD; (d) Effect of the modified BFD dosage on Zeta potential. (e) The pH_zpc of these three BFDs (MBFD, MBFD2, BFD).

Figure 7. Mechanism of the MBFD demulsification.

Table 4. Three-stage kinetic fit results.

Stage	T(min)	Kinetic equations	kobs(mg/L·min)	R^2
1	0–10	Zero-level dynamics($\mathrm{y}=7875.42-45.85\mathrm{x}$)	45.85	0.977
2	10–20	Zero-level dynamics($\mathrm{y}=-200.25\mathrm{x}+9393.8)$	200.25	0.994
3	20–100	Pseudo-level dynamics ($\mathrm{y}=4965.41{\mathrm{e}}^{-54.19\mathrm{x}})$	54.19	0.959

Table 5. COD_cr removal efficiency of modified the BFD different dosage.

Dosage(g·L^−1)	0.8	0.9	1.0	1.1	1.2	1.3	1.4	1.5
Degradation efficiency(%)	78.90	80.61	83.76	85.21	84.45	80.38	75.29	72.56

Table 6. Water quality comparison of five batches of wastewater; Experimental condition: MBFD: 1.2 g·L⁻¹, pH: 5, G^–:36 S⁻¹.

Batch	1	2	3	4	5
CODCr(mg·L^−1)	6181.52	8017.40	8186.28	8437.09	7750.93
Degradation efficiency (%)	80.08	83.51	83.86	81.92	79.45

Data availability statement

Data available from the corresponding author on request.