Surface interactions of oxytetracycline on municipal solid waste-derived biochar–montmorillonite composite

Figures & data

Figure 1. SEM images of MSW-BC (a) and MSW-BC-MMT (b) with visual modifications.

Table 1. BET surface analysis results and interlayer spacings (d001) in MSW-BC, MSW-BC-MMT and their changes with OTC interaction

Adsorbent	Surface area (m^2 g^−1)	d001 value (Å)
MSW-BC	4	-
MMT	36	15
MSW-BC-MMT	7	12
MSW-BC-MMT-OTC	-	18

Figure 2. PXRD patterns of MSW-BC, MMT, MSW-BC-MMT and MSW-BC-MMT-OTC.

Figure 3. FTIR spectrum of pure (a) MSW-BC, MMT and OTC material along with the treated and untreated composites. (b) Enlarged spectrum from the wavelengths of 1200–1700 cm⁻¹.

Figure 4. pH vs OTC adsorption capacities of MSW-BC and MSW-BC-MMT composite.

Figure 5. Redlich–Peterson and Temkin isotherm models for the adsorption of OTC by MSW-BC-MMT composite.

Table 2. Kinetic and isotherm model parameters for the adsorption of OTC onto MSW-BC-MMT

Model	Parameters	MSW-BC-MMT
Pseudo-second-order model	qe (mg g^−1)	7.81
	K2 (min^−1)	0.0236
	Adj. R^2	0.9998
Elovich	a (mg g^−1 min)	2.72 x 10^8
	B (mg g^−1 min)	3.499
	Reduced Chi-Square	0.129
	Adj. R Square	0.934
Redlich–Peterson isotherm	KR (L mg^−1)	53.487
	aR	0.231
	Reduced Chi^2	57.397
	Adj. R^2	0.998
Temkin isotherm	A (L g^−1)	21.326
	b	77.658
	Reduced Chi^2	126.841
	Adj. R^2	0.997

Figure 6. Elovich kinetic model and pseudo-second-order model for adsorption of OTC by MSW BC-MMT composite.

Figure 7. Conceptual illustration of the possible mechanisms of OTC adsorption on MSW-BC-MMT composite.