SYNTHESIS AND CHARACTERIZATION OF CARBOXYMETHYL CELLULOSE (CMC) FROM DIFFERENT WASTE SOURCES CONTAINING CELLULOSE AND INVESTIGATION OF ITS USE IN THE CONSTRUCTION INDUSTRY

Abstract

This study aimed at the recovery of cellulose from abundantly available wastes and its sustainable application. Firstly, in the cleaning process, cellulose-containing wastes, such as “air particle vacuum powder” (APVD), “towel clippings” (TC), and “cottonseed delintation residues” (CD), were thoroughly washed, separately, with tap water to remove some organic and inorganic impurities. The cotton slurry was purified by 17.5% NaOH at 90 oC for about 4 hours, then filtered and washed with tap water. Afterwards, the resulting pulp was bleached by NaOH and H2O2, and washed with distilled water until neutralized. Secondly, for the synthesis of carboxymethyl cellulose (CMC) from the above-dried celluloses, optimum conditions were achieved by varying the concentrations of components and ambient conditions. In the sample coded TCCMC3, a maximum degree substitution (DS) of 1.22, the highest consistency, the highest penetration time and the highest viscosity with 2520 centipoises (cP) were obtained from the reaction of towel clippings with 5.62 g sodium hydroxide and 13.12 g monochloroacetic acid (MCA) at 65 oC for 3 hours. Finally, the effect of these synthesized CMCs on the consistency and penetration time of a cement paste was investigated. The consistency of standard Portland cement (PC), without CMC addition, was 5 mm in the Vicat test, while the values measured for the cement pastes to which TCCMC3, APVDCMC3 and CDCMC3 were added reached 36.5 mm, 28.0 mm and 13.0 mm, respectively. While the setting time in the standard sample (Portland cement paste, PCP) was between 2.20-4.10 hours, this time shifted to 3.30-7.00 hours, with a maximum setting time recorded with the addition of TCCMC3. Besides, while the penetration time for APVDCMC3 started at 3.10 hours and was completed at 5.30 hours, for CDCMC3, it ranged between 2.40 and 4.40 hours, leaving it without hydration in a higher time interval than in the case of standard Portland cement paste. As a result, it has been found that carboxymethyl cellulose synthesized by the etherification reaction of cellulose obtained from recycled wastes for industrial uses, in an aqueous alkali environment, can be applied as a thickener in the construction industry and other fields.