Synthesis and Characterization of Carboxymethyl Cellulose from Eichhornia crassipes and Pennisetum purpureum as Potential Source of Sustainable Drilling Mud Additives

Abstract

Cellulose extracted from Eichhornia crassipe (Water hyacinth) and Pennisetum purpureum (elephant grass) yielded 21.88% and 31.39% respectively. Cellulose extracted was used to synthesize carboxymethyl cellulose (CMC) under heterogeneous condition with ethanol as the supporting medium. Effect of concentration of sodium hydroxide (NaOH) on the modification of cellulose to yield CMC was investigated. It was observed that percentage CMC yield increased with increase in NaOH concentration. Comparative studies of the two biomass samples through physico-chemical analyses in terms of degree of substitution (DS), water absorption capacity, water loss, pH, conductivity and analytical characterization using SEM-EDX, FT-IR and EDXRF spectroscopy of the extracted cellulose and synthesized CMC were done. The DS of CMC obtained by alkalization reaction of cellulose from E. crassipe and P. purpureum with monochloroacetic acid was in the range of 0.54-0.75 which showed that it is highly soluble. Fourier Transform-Infrared (FT-IR) spectrophotometer showed changes of functional group from cellulose to CMC. The absorption at 3283 cm-1 and 3320 cm-1 as observed in E. crassipe and P. purpureum spectra showed OH vibration of polymeric compounds. The presence of bands at 1592 cm-1 and 1417 cm-1 in E. crassipe spectrum and bands at 1566 cm-1 and 1410 cm-1 observed in P. purpureum spectrum showed the presence of –COO group as a result of carboxymethylation reaction on cellulose during modification process. EDXRF was applied for quality control and product development due to the unavailability of the elemental composition of elephant grass and water hyacinth in the literature. The morphology and elemental compositions on the surface of the biomass were analyzed by SEM-EDX and among the chemical elements detected were C, O, Na, Mg, Al, S, Cl, K, Ca, Fe Si and Zr which confirms the elements identified with EDXRF spectroscopy. XRF spectra show high peaks at Fe, K and Sn for untreated P. purpureum samples and high peaks at Ca, Fe and Sr for untreated E. crassipe fiber. Both samples are rich in Iron (Fe). Samples were free from some toxic elements such as Pb, As, Hg, V and Ni which makes them safe for use as novel raw materials for industrial applications. Also very low concentration of Sulphur in the samples, make them safe to be considered as additives in drilling mud formulation.