Aqueous norfloxacin removal by novel biochar adsorbent prepared through ethanol-combined ball milling

Figures & data

Table 1. Elemental contents of p-BC, C₂H₆O-BC and C₂H₆O-BC after nor adsorption.

	C	H	N	O
	(%)	(%)	(%)	(%)	O/C	H/C
p-BC	54.6	2.73	1.89	28.5	0.39	0.60
C2H6O-BC	55.0	3.42	1.89	30.5	0.42	0.75
C2H6O-BC+NOR	56.7	3.22	1.99	32.2	0.43	0.68

Figure 1. SEM images of p-BC (a) and C₂H₆O-BC (b), N₂ adsorption and desorption isotherms (c) and FT-IR spectra of unloaded and NOR/Cu-loaded biochars (d).

Figure 2. Adsorption isotherms, kinetics and the related comparisons and fitting [(a) adsorption isotherms; (b) comparison of NOR adsorption capacity by C₂H₆O-BC with that by unmodified/modified hydrothermal/slow pyrolyzed biochars reported in literature [34–38]; (c) adsorption kinetics ; and (d) mass transfer process simulated by weber-morris model].

Table 2. Adsorption fitting parameters of C₂H₆O-BC and p-BC.

	Parameters						C2H6O-BC			p-BC
Isotherm model parameters of C2H6O-BC and p-BC.
Temkin	KT (L/mg)						4.9			0.600
	BT (J/mol)						24.7			4.20
	R^2						0.955			0.747
Freundlich-Langmuir	KLF ((L/mg)^1/n)						13.5			9.07
	Qmax (mg/g)						53.1			7.05
	n						0.762			0.791
	R^2						0.974			0.864
Redlich-Peterson (RP)	KRP (L/g)						98.3			3.07
	aRP (L/mg)						0.920			0.520
	β						0.900			0.630
	R^2						0.960			0.968
Kinetic parameters of C2H6O-BC and p-BC.
	PFO			PSO			Elovich			Ritchie
	K1	Qe	R^2	K2	Qe	R^2	α(	β	R^2	α	qe	n	R^2
C2H6O-BC	1.33	84.3	0.850	0.025	90.3	0.953	827	0.072	0.961	0.070	85.0	1.80	0.947
p-BC	0.406	11.8	0.928	0.032	14.0	0.967	9.40	0.310	0.984	0.140	12.9	1.36	0.967
Parameters of mass transfer process of C2H6O-BC and p-BC.
	Weber and Morris						Mathews and Weber
	Kid		C		R^2		KMW		R^2
C2H6O-BC	49.9		12.9		0.967		1.55		0.889
p-BC	3.54		0.511		0.990		0.267		0.966

Figure 3. Effect of solution initial pH on NOR adsorption onto C₂H₆O-BC (bichar 2 g L⁻¹, 24 h)(a), co-existing Cu(II) (bichar 1 g L⁻¹, 24 h) (b) and solid-liquid ration (1: 0.5 g L⁻¹; 2: 1 g L⁻¹; 3: 2 g L⁻¹; 4: 4 g L⁻¹, 24 h) (c).

Figure 4. Fixed bed adsorption of NOR adsorption by C₂H₆O-BC [(a) sorption of NOR with influent concentration of 15 mg L⁻¹ (NOR1), 100 mg L⁻¹ (NOR2) and 200 mg L⁻¹ (NOR3); (b) Thomas model fitting; (c) Yoon-nelson Model fitting; (d) effects of high concentration of Cu(II) (15 mg L⁻¹ NOR +100 mg L⁻¹ Cu); (e) effects of Cu(II) preloading (200 mg L⁻¹ NOR after preloading of 120 mg L⁻¹ Cu); and (f) co-transport of 200 mg L⁻¹ NOR +120 mg L⁻¹ Cu as a comparison for preloading experiment].

Table 3. Removal ratios of nor by C₂H₆O-BC via STBR.

STBR				Batch adsorption
Biochar (g/L)	t (h)	Removal ratios of stage 1(%)	Removal ratios of stage 1 + 2(%)	Biochar (g/L)	t (h)	Removal ratios (%)
0.5	2	40.4 ± 0.6		1	2	69.8 ± 0.4
0.5	2		81.3 ± 0.4		4	78.4 ± 0.6
1	2	70.7 ± 0.4		2	2	98.6 ± 0.1
1	2		98.7 ± 0.1		4	98.7 ± 0.1

Figure 5. The XPS spectrum of C₂H₆O before and after adsorption [(a) the full XPS spectrum and (b) the high-resolution XPS spectrum of C1s, O1s and Cu2p].

Data availability statement

Data will be made available on request.