Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor

Table 1 Compensated chemicals added into non-reacted mother liquor for MCM-41 synthesis cycles and MCM-41 solid yield

MCM-41 synthesis	1st cycle	2nd cycle	3rd cycle
Non-reacted mother liquor (g)	0	54.404^a	63.337^a
Added reagents
Na₂SiO₃ (g)	21.206	15.664	15.560
CTABr (g)	5.772	3.750	3.251
H₂O (g)	79.916	31.882	27.110
H₂SO₄ (g)	0.603	2.082	0.9881
pH	10.78	10.80	10.80
Solid yield, gram (wt.%)^b	8.034 g (73.6%)	7.851 (71.9%)	7.694 (78.3%)

^aAfter evaporating water at 55°C for 16 h.
^b $Solid yield (%) = \frac{Weight of calcined solid after water being removed (g)}{Initial weight of Si O_{2} (g)} \times 100 %$ .