Performances of a Polysilicon Byproduct - Silicon Tetrachloride - on Swelling and Tanning Process

Sodium silicate was prepared with a polysilicon byproduct-silicon tetrachloride. The swelling property of the sodium silicate was then investigated including proteoglycan removing ability, silicon absorptivity, relative weight and thickness increase. Meanwhile, a new process for cleaner wet blue preparation was carried out. Properties of the wet blue such as mechanical properties, thermal stability and surface color were tested following the standard method. Chrome distribution of the wet blue was investigated with an inductively coupled plasma (ICP). A scanning electron microscope (SEM) and a atomic force microscope (AFM) were also used to illustrate the histological features of the wet blue. Finally, environmental impact of both swelling and tanning process were studied through COD, chrome contention, total solids and turbidity test. The results showed that the swelling ability of these silicate agents was distinctly related with their modulus. The lower the modulus, the better the swelling ability was shown, in terms of a higher relative weight and thickness increase, a better proteoglycan removing and a better silicon absorptivity. The SEM analysis indicated fiber bundles were fully opened with this silicate agent. For the wet blue prepared by new method, an equally quality data was shown compared with control, meanwhile, a lighter surface color, less and equally distributed Cr(III) were detected. More compact fiber bundles were shown on the SEM images. No obvious damage was detected in tropocollagen fiber structures through AFM analysis. Furthermore, compared with the traditional process, COD, total solids and turbidity data of both swelling and tanning effluent provided a lower value. The results could provide a feasible way for silicon tetrachloride recycling, also provide valuable references for clean production of leather industry.