The Effect of Dissolved Humic Acids on Aluminosilicate Formation and Associated Carbon Sequestration

Table 4

The percentage of imogolite-like Si from ²⁹Si NMR, corresponding to the integrated relative intensity of the peak at −78.3 ppm. The 𝛿_Si-29 of the gel component is the weighted average of the broad signal, excluding the imogolite-like peak. Also reported is the percentage of Al in 4-, 5-, and 6-fold coordination from ²⁷Al NMR.

Sample	^29Si NMR		^27Al NMR
	Imogolite-like Si percent	𝛿Si-29 gel	Al^(IV) percent	percent Al^(V)	Al^(VI) percent
0.5 mM Al-Si	10	−85.7	18	5	77
0.5 mM Al-Si-DOC	10	−87.9	16	5	79
0.75 mM Al-Si	20	−83.1	24	5	71
0.75 mM Al-Si-DOC	23	−84.0	16	5	79
1.0 mM Al-Si	18	−84.6	26	5	69
1.0 mM Al-Si-DOC	21	−85.8	22	5	73