Table 3.

Levels of the variable in the RSM.

Variables	Symbol	Unit	Levels
			− α	Lower	Central	Upper	+ α
Adsorbent dosage	A	mg	200	250	300	350	400
pH of the solution	B	–	4	6	8	10	12
MG concentration	C	mg L−1	2	4	6	8	10
AO concentration	D	mg L−1	2	4	6	8	10
Sonication time	E	Min	3	6	9	12	15