Fire is the major revolutionary discovery of humans with a two-edged sword in that it is used in almost every aspect of daily life and industry, but it also causes significant damage. Every year approximately 0.2% of the global economy is lost due to fire disasters without counting its reconstruction and other medical-related issues (Li et al., 2011; Chen et al., 2015; Li et al., 2010). The primary benefit of flame-related research is the development of highly effective materials capable of protecting both human life and society. Among the various flame retardants available, the fabric containing flame retardants is gaining popularity due to its mechanical properties and lack of comfort (Weil et al., 2008; Horrocks et al., 2005). These fabrics are used for soft furnishings, and unmodified cotton fabric are highly flammable (Li et al., 2011; Devaux et al., 2002; Alongi et al., 2014) As a result, the way of making fabric flame retardant is surface modification. Surface modification is cost-effective, simple, frequently utilized, and possess an enormous practical approach (Wang et al., 2020; Zhang et al., 2021; Kim et al., 2014). The choice of the flame retardant is also playing an important role. Originally, boron, silicon, and halogen-based flame retardants were widely employed, but they were phased out because they emit dangerous chemicals into the environment causing deleterious effects on human health’s (Wakelyn et al., 2007; Hsiue et al., 1999; Mercado et al., 2006). For the surface modification, dipping (Xu et al., 2019) and layer-by-layer (LBL) (Li et al., 2010; Laachachi et al., 2011) self-assembly were utilized as simple and extensive approaches to improve the flame retardancy of cotton fabric. In that, the cotton fabrics were originally treated with intumescent flame retardant coatings by Li et al. (Li et al., 2011) This sort of coating is extremely effective, beneficial, and versatile in the fabrication of flame retardant coatings on a variety of substrates (Li et al., 2010; Laachachi et al., 2011; Laufer et al., 2012).
The eggshell employed as a bio-filler was commonly utilized as an intumescent flame retardant coating because it includes a high quantity of calcium carbonate (CaCO3), i.e., about 95% while 5% of other organic components. Intumescent fire-retardant coating, which is largely composed of an intumescent fire-retardant system, a synergist, a binder, and an auxiliary agent, is considered as one of the most effective materials for shielding substrates from fire hazards (Yan et al., 2018). Researchers are interested in using polymer because of its simple compatibility with bio-filters, fire resistance, and mechanical characteristics (Yew et al., 2018). The intumescent flame retardant has lately become a pandemic FR for polymers because of its low smoke, halogen-free, low toxicity, and excellent efficiency (Xueying et al., 2015; Zhang et al., 2018). Researchers have been drawn to developing novel intumescent flame retardant systems using bio-based flame retardants like starch (Olivares et al., 2019; Oassaure et al., 2019), chitosan (Cheng et al.,), and lignin (Song et al., 2016; Liu et al., 2016). Acid was widely utilized to improve the flame retardant characteristic of bio-filler-containing products (Yeh et al., 1995; Duquesne et al., 2004). These flame retardants mainly consist of acid source, blowing agent, and binder. When these types of flame retardants come in contact with the flame, they produce black smoke, heat, and toxic gases (Chen et al., 2016). Also, such type of flame retardants has a limited scope of application, which means they cannot be applicable on cotton fabric.
In addition to the eggshell, seashell (Moustafa et al., 2017), clamshell (Li et al., 2020), and conch shell (Wanf et al., 2021) were utilized as bio-fillers, along with various acid, polymer, and binder sources, to increase the flame retardant characteristics of the composite. The application of these chemicals enhances flame retardant efficiency while also protecting the composition. The usage of these compounds (chemicals) to emphasize the flame retardant characteristic of the composite has a very hazardous effect on the environment and human. These sorts of composites may create health issues such as allergic reactions, skin inflammation, and so on (Tesghai et al., 2019). There is a need to modify the bio-filler in such a way that it should take care of all the aspects of ecology with the enhanced flame retardant property.
Long-lasting phosphorus-containing flame retardant materials have fastened attention due to their efficacy, such as low toxicity, reducing the volatility of fuels, producing the carbon-based char, lowering the pyrolysis temperature, wash fastness resistivity and reducing the afterglow. Phosphorus-containing flame retardants benefit from being effective in both the gaseous and condensed phases by generating chain reactions and producing a shield through char formation, respectively (Fang et al., 2020; Dhumal et al., 2022., Yun et al., 2011). The phosphorous functionalization was done in various techniques, including sponges, poly cables, and textiles (Chen et al. 2012). The phosphorous functions can dehydrate cellulose and increase char formation (Wicklein et al., 2015; Song et al., 2017). Many researchers used the phosphorous-graphene strategy for efficient flame retardancy such as DES functionalized (Pethsangave etal., 2017), polymer-based (Pethsangave et al., 2019), GO in ABS (Higginbotham et. Al., 2009), and FR-GQD (Khose et al., 2018). Graphene is forthcoming as a very attractive support material for flame retardation systems. It is a perfect fit for the skeleton of flame retardant materials due to its large surface area, high oxygen-rich active functionalities, low toxicity potential and thermal stability. As a result, society continues to demand efficient materials that are simple to produce, environmentally benign, cheaper in cost, and gentle in nature. According to the literature, the modified bio fillers-based flame retardant may be enhanced by the functionalization of phosphorous groups in the presence of graphene as a high surface area containing a suitable carbon-based skeleton.
As a result of the need for an environmentally friendly, easy-to-prepare flame retardant nanocomposite, we synthesized one from biowaste. In this, the biowaste (eggshell) was treated with phosphoric acid before being reacted with graphene oxide to prepare a nanocomposite for flame retardant applications. Eggshell was converted to monocalcium phosphate by phosphoric acid treatment, which was functionalized with graphene to prepare graphene functionalized monocalcium phosphate (GCP). The prepared composite can sustain in the continuous flame for more than 10 min (600 s) as compared to the blank cotton fabric (5 s), coated fabric GO (15 s), and CP coated fabric (10 s). The coating of the GCP is a very simple and easy method that requires a concise time. Compared to the blank cotton fabric, GO coated cotton fabric, and CP coated fabric, the produced composite can maintain the flame for more than 10 minutes.