## 1 Introduction  
The use of natural raw materials for the synthesis of polymers and polymer-based products has been one of the most vital innovations in recent years [1; 2; 3; 4; 5]. The use of biomass-based materials has received genuine attention due to their availability, relatively low-cost and favorable sustainability profile [6]. One of the major agricultural waste materials in Malaysia is lignocellulosic biomass from sago starch industries. Lignocellulose contains three main components: an amorphous hemicellulose, a semi-crystalline cellulose and amorphous phenylpropanol called lignin [7]. The complete and efficient re-use of lignocellulosic into usable value-added materials has been a major challenge for both chemical and biological methods. In the overall processes, it is critical to deconstruct the 3D structure of the lignocellulosic by separating the semi-crystalline cellulose and hemicellulose without causing much degradation to the polysaccharide they are formed from [8].  
Cellulose has been extracted from different sources [9; 10; 11; 12] by different methods, e.g., chemical, mechanical, biological and chemo-mechanical [13; 14; 15; 16], but the quality varies widely depending on the source of the cellulose. The most expensive method uses biology, whereas a combination of chemical and mechanical methods shows evidence of producing cheaper and efficient methods of extraction [17]. Native cellulose has a wide range of applications, but it also shows some undesired properties which limit their use. Cellulose has two major polymorphs. In most plants, cellulose I is predominant while cellulose II is found in simpler species like algae allomorphs, in which parallel and antiparallel orientation of the glucan chain is observed. As a material, cellulose exhibits no response to change in pH, solubility in water or other organic solvents. Strong alkali treatment can be employed to alter the crystallinity of cellulose I. Cellulose substituted with alkyl groups, such as methyl, ethyl, hydroxymethyl, hydroxpropyl, and carboxymethyl, produce polymers with variable, and tunable physicochemical properties. Being produced from renewable natural resources has economic gains over synthetic polymers, and, as such, cellulose polymers are utilized in various industries.  
One such cellulose derivative is carboxymethyl cellulose (CMC), which possesses strong interactions with metal ions due to the presence of carboxylate and hydroxyl groups. CMC is used in many industries like food, personal care, detergent, mining flotation, paper making, oil drilling and textile industries because of the high viscosity, water preservation, robust acid and salt resistances [18]. There is a recurrent interest in finding cheaper alternative sources for producing CMC, especially since it is widely used at scale in agriculture, forestry, life sciences and chemical communities of United States of America [19].  
Methods are available to prepare CMC from natural biomass such as banana plants and sugar beet pulp [20; 21]. The synthesis of CMC with hydrogel properties usually involves the reaction of cellulose with sodium monochloroacetate under alkaline conditions [22; 23; 24]. We previously reported synthesis and characterization of carboxymethyl sago pulp (CMSP) hydrogels from sago waste [25]. CMSP, is a water-soluble derivative of cellulose that exhibits high solubility [26] and chemical stability, is safe, non-toxic, hydrophilic, as well as biocompatible and biodegradable [27] hence adhering closely to green chemistry principles [26]. In this research, a modified and extraction efficient method to produce cellulose I and carboxymethyl sago cellulose (CMSC) from sago biomass are explored. The purified CMSC was compared to commercial-grade CMC and found to conform to specifications for CMC in the American Society for Testing and Materials (ASTM) standards.