Table 1. Observed pseudo-first order rate constants for the reaction of Py on the substrates examined in this study with 3 ppmv NO₂ (k_obs), apparent reaction probabilities of NO₂ with the surface-adsorbed Py (γ), percentage of degraded Py (D_Py), yields of 1-NP (Y_1−NP), and initial surface coverages of Py (θ_Py,0).

Substrates	kobs × 105 (s−1)*	γ × 108*	DPy (%)†	Y1−NP (%)†	DNP formation‡	θPy,0 × 102
Chinese desert dust (CDD)	86 ± 4	14 ± 1	96	53	+	2.8
Arizona test dust (ATD)	36 ± 1	6.1 ± 0.2	88	58	+	7.7
Kaolin§	110 ± 10	18 ± 1	98	60	+	1.5
Montmorillonite A	53 ± 5	9.0 ± 0.8	95	89	+	2.0
Montmorillonite B	29 ± 4	4.9 ± 0.7	84	79	+	5.8
Saponite	39 ± 3	6.6 ± 0.4	82	73	−	0.27
Potassium feldspar	1.1 ± 0.2	0.19 ± 0.03	14	10	−	11
Sodium feldspar	0.30 ± 0.06	0.05 ± 0.01	12	6	−	58
Feldspar	0.86 ± 0.14	0.15 ± 0.02	17	4	−	27
Limestone	1.4 ± 0.1	0.24 ± 0.01	18	5	−	21
Dolomite	0.83 ± 0.15	0.14 ± 0.03	16	4	−	11
Calcium sulfate	1.5 ± 0.5	0.25 ± 0.09	6	0	−	49
Quartz	1.7 ± 0.1	0.28 ± 0.01	9	5	−	63
Aluminum oxide	0.25 ± 0.00	0.04 ± 0.00	2	1	−	6.7
Iron (III) oxide	9.0 ± 3.3	1.5 ± 0.6	17	0	−	6.9
Titanium (IV) oxide	1.4 ± 0.0	0.24 ± 0.00	14	3	−	5.2
Montmorillonite K10||	250 ± 20	43 ± 3	100	6	+	0.72
ATD w/ NH3 titration¶	15 ± 2	2.5 ± 0.4	62	31	−	7.7
Graphite#	1.9 ± 0.1	0.32 ± 0.01	9	1	−	2.6

^*Errors represent one standard error derived from nonlinear least-squares fitting for the Py decay plots.

^†Obtained from reactions for 2 h.

^‡Reaction time, 12 h; +, yes; −, no.

^§Note that kaolin consists largely of kaolinite.

^||Acid-activated montmorillonite.

^¶Acidic surface of ATD was pre-titrated with NH₃. See Methods for details.

^#As a control.