Rapid Preparation of Biosorbents with High Ion Exchange Capacity from Rice Straw and Bagasse for Removal of Heavy Metals

Table 2

Reaction conditions for preparations of modified rice straw, phosphorus content, degree of substitution, and ion exchange capacity of the modified rice straw.

Sample names	Heating methods	Conditions	% P	Degree of substitution	Ion exchange capacity (meq/g)
RS*	—	—	—	—	0.12*
RS-oil 2 hr	Oil bath	150°C 120 min	2.85	0.16	1.29
RS-oil 3 hr	Oil bath	150°C 180 min	2.11	0.12	0.99
RS 300 W	Microwave	300 W 5 min	3.03	0.17	1.30
RS 450 W	Microwave	450 W 3 min	3.75	0.22	1.73
RS 600 W	Microwave	600 W 2 min	3.66	0.21	1.64
RS 800 W	Microwave	800 W 1.5 min	3.49	0.20	1.51
RS-DMF oil 2 hr	Oil bath	150°C 120 min	2.65	0.15	1.13
RS-DMF oil 3 hr	Oil bath	150°C 180 min	5.74	0.35	2.46
RS-DMF 300 W	Microwave	300 W 5 min	3.14	0.18	1.36
RS-DMF 450 W	Microwave	450 W 3 min	3.27	0.19	1.34
RS-DMF 600 W	Microwave	600 W 2 min	3.56	0.21	1.48
RS-DMF 800 W	Microwave	800 W 1.5 min	3.14	0.18	1.24
RS-NaOH oil 2 hr	Oil bath	150°C 120 min	6.23	0.39	2.98
RS-NaOH oil 3 hr*	Oil bath	150°C 180 min	6.32	0.39	2.99*
RS-NaOH 300 W	Microwave	300 W 5 min	5.96	0.37	2.21
RS-NaOH 450 W*	Microwave	450 W 3 min	7.07	0.45	2.61*
RS-NaOH 600 W	Microwave	600 W 2 min	6.99	0.45	2.50
RS-NaOH 800 W	Microwave	800 W 1.5 min	7.04	0.45	2.58

∗Samples for sorption test.