Redox activity and accelerating capacity of model redox mediators during biodenitrification

Figures & data

Figure 1. Denitrification and nitrite accumulation in the presence of various redox mediators.

Figure 2. Changes in the ORP during denitrification in the presence of various redox mediators.

Figure 3. Cyclic voltammograms of the four studied redox mediators at a scan rate of 10 mV s⁻¹.

Table 1. Characteristics of the cyclic voltammetry of the redox mediator.

	$E_p^A$, mV	$E_p^C$, mV	ΔEp, mV	E1/2, mV	$i_p^a$, μA	$i_p^c$, μA	$i_p^a/i_p^c$
α-AQS	−58	−215	157	−136.5	47	45	1.04
AQS	−46	−218	172	−132	22	−43	−0.51
AQDS	−36	−210	174	−123	24	−49	−0.49
2,7-AQDS	0	−145	145	−77.5	32	−62	−0.51

Note: 35 °C, pH 1.25 and 10 mV s⁻¹.

Table 2. Energy of HOMOs (E_HOMO) and LUMOs (E_LUMO) of the studied molecules and their energy gaps ΔE.

	ELUMO, au	EHOMO, au	ΔE, au
α-AQS	−0.12382	−0.27804	0.15422
AQS	−0.12847	−0.28251	0.15404
AQDS	−0.14589	−0.29929	0.15340
2,7-AQDS	−0.14609	−0.29929	0.15320

Figure 4. Molecular structure of α-AQS.