Corrosion Inhibition of Mild Steel in Acidic Media by 5′-Phenyl-2′,4′-dihydrospiro[indole-3,3′-pyrazol]-2(1H)-one

Table 1

Inhibition efficiencies of SPAH for the corrosion of mild steel obtained by weight loss measurements.

Name of the inhibitor	Inhibitor concentration (ppm)	Weight loss (g)	Corrosion rate (mpy)	Inhibition efficiency (%)	Surface coverage (θ)
1 M HCl	Blank	0.0863	1227
	1	0.0549	780	36.4	0.3638
	3	0.0447	635	48.4	0.4840
	5	0.0361	513	58.2	0.5816
	7	0.035	497	64.7	0.6465
	9	0.0261	371	69.8	0.6975
0.5 M H2SO4	Blank	0.1611	2290
	1	0.0938	1333	41.8	0.4177
	3	0.0623	885	61.3	0.6132
	5	0.0424	603	73.7	0.7368
	7	0.0385	547	76.1	0.7610
	9	0.0342	486	78.8	0.7877