Synthesis And Performance Of Biodegradable And Non-phosphorous Detergent Builders

For a long term, phosphate detergent builder represented by sodium tripolyphosphate (STPP) had been widely used in synthetic detergent industry because of its good building properties. Unfortunately, its widespread application has caused the eutrophication of water systems and the destruction of the ecologic environment. Sodium polyacrylates are the new generation of non-phosphorous detergent builders which have many advantages such as excellent detergency, resistance to hard water and non-toxicity, but their degradability is poor, so they also can cause environmental problems because of their long-term accumulation in environment. In the hope of improving the degradability of the sodium polyacrylates, in the study,2-methylene-1,3-dioxepane (MDO) was incorporated into the sodium polyacrylates.MDO can be synthesized by a two-step reaction. At first, an intermediate Cl-MDO was synthesized by condensation reaction of chloroacetaldehyde dimethyl acetal and1,4-Butanediol (BDO) with the catalyst of D001ion exchange resin. Secondly, MDO was synthesized by reaction of Cl-MDO and potassiun t-butoxode by using t-butyl alcohol as solvent. The crude product was washed by ethyl ether fully and fractionally distilled to produce MDO. The purity and structure of MDO were characterized by gas chromatography, flourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (’H-NMR).MDO was copolymerized with acrylic acid (AA) neutralized partially by NaOH aqueous solution to prepare a series of copolymers which had ester units in the backbone chain and carboxyl as pendant functional groups. The influence of different technics on detergent properties had been discussed in the paper. The optimized technological conditions were the monomer concentration25%, the mass content of MDO8%, the mass content of initiator6%, the mass content of TBAB4%, the reaction temperature80℃, the reaction time8h. The chelating capacity, dispersancy and pH buffer ability of the copolymer are540.49mg (CaCO3)·g-1,133.52mg (CaCO3)·g-1and1.22mL (HCl)·g-1respectively.The structures and weight-average molecular weights (Mw) were characterized by FTIR、1H-NMR and multi-angle laser light scattering instrument (MALLS). The results demonstrated that MDO underwent free-radical ring-opening polymerization with AA to give copolymers which have ester units in the backbone chain and carboxyl as pendant functional groups. As the MDO content increased, the molecular weight of the copolymers increased firstly, then decreased again. The molecular weight was the most when the mass content of MDO was6%.The thermal property of the copolymers was investigated by differential scanning calorimetry (DSC) and termogravimetric analysis (TGA). It was found that the Tg and initial decomposition temperature of copolymers decrease with increasing the MDO content. The thermostability of the copolymers declined as the MDO content increased, but still maintained at a high level to meet the requirement of production process of detergent builders. The crystallization of the copolymers was tested by X-ray diffraction (XRD) and results showed that the P(AA-co-MDO) copolymers were amorphous and these copolymers may have good biodegradable performance.The biodegradability of the copolymers was studied by Shaking-Bottle Incubating Test. The research indicated that building properties of the copolymers become worse and the biodegradability of the copolymers become better with increasing the MDO content in the P(AA-co-MDO) copolymers. It was found that the copolymers with8%MDO content had good building properties and biodegradability.