Evaluation Of A Analytical Experiment - 1296 Words

Analytical reagent grade sodium hydroxide, hydrogen peroxide, ethanol, AA, N,N†²-methylenebisacrylamide (MBA), AMPS, potassium Persulfate (KPS) were supplied by Tianjin Fuchen Chemicals. Corn straws were purchased from Huimin County, Binzhou City, Shandong Province. 1.1 Preparation of sulfonic cellulose by pretreating corn straws Dry corn straws were ground and sieved using a 40-mesh sieve. Then, the resulting corn straw crash was made alkaline with 15% NaOH solution at 55  °C in a water bath for 2.5 h. The resulting solution was oxidized and bleached by H2O2, dried, and ground to get cellulose. Cellulose was immersed in 17.5% NaOH solution and stirred for 1 h, followed by immersing for 3 h. Then, it was washed and neutralized with†¦show more content†¦In the meantime, the control sample hydrogel was synthesized by AA without the sulfonated cellulose. The formulation for the control sample is listed in Table 1. The resulting hydrogels were dried at 80  °C in an oven for 24 h and then ground. 1.3 Measurements of hydrogels 1.3.1 Measurement of swelling ratio Q After sieving the dried hydrogels using a 40-mesh sieve, a certain amount of sample was transferred to a tea bag, which was further immersed in deionized water for 48 h at room temperature. After the swelling equilibrium was achieved, the samples were weighed. The swelling ratio (Q) was calculated by the following formula. Q = (W1 – W0)/W0 where W0 and W1 are the mass of the dry and swollen hydrogels, respectively. 1.3.2 FTIR analysis of hydrogels The corn straws, pretreated corn straws, and hydrogels were ground into fine powders, mixed with KBr, and pressed into pellets for FTIR analysis. FTIR spectra were scanned in the wavelength range 400–4,000 cm-1. 1.3.3 Measuring the swelling dynamics of hydrogels A certain amount of hydrogels was transferred to a tea bag. Then, the tea bag was immersed into deionized water. The mass was measured at regular intervals until it become constant. 1.3.4 Salt resistance of hydrogels NaCl, CaCl2, and AlCl3 solutions with different concentrations were prepared. The dry hydrogel samples with the same mass were immersed in salt solutions. Salt resistance was determined by the swelling ratio when the hydrogel