| Recently,organic-inorganic composites or hybrids have attached extensive attention in the field of material chemistry.These composites or hybrids exhibit interesting characteristics and novel electronic,mechanical,electrochemical and optical properties.Through the combination of inorganic materials and organic fibers,the high-reflected,low-adsorbed,fire-proof and heat-insulated textile can be obtained.Mg(OH)2 has been extensively used as flame retardant and the smoke suppressant in various polymeric materials due to its ability to undergo endothermic dehydration in fire conditions.Both it self and its dehydrated products MgO are environmental friendly flame retardants.However,its application to textile is rarely reported.In our study,Mg(OH)2 lamellar nano-crystals have been grown on citric acid modified cotton fabric by secondary crystallization,which can provide the fabric with special properties.Firstly,the isothermal adsorption model between Mg(OH)2 crystal seeds and modified cotton fabric induced by the combination of Mg2+and Cell-COO- was investigated.Batch experiments of varied concentration carboxyl groups under fixed temperature 35℃were conducted to determine the adsorption capacity.Kinetics and adsorption equilibrium were studied at different adsorption time and different concentration of Mg(OH)2 crystal seeds.The adsorption process was quick and the equilibrium was attained within 30 minutes.Furthermore,PVP dispersion has a strong influence on adsorption characteristics and maximum adsorption capacity.The kinetic data were analyzed using various kinetic models pseudo-first order equation,pseudo-second order equation and intraparticle diffusion equation,while the equilibrium data were tested using Langmuir and Freudlich isothermal models.The pseudo-second order equation and Langmuir model provide closest fit for kinetic and equilibrium data.Secondly,the secondary crystallization of lamellar Mg(OH)2 nano-crystals on modified cotton fabric was studied.Mg(OH)2 was provided by a simple reaction of MgCl2 and NH3·H2O, without any organic additive or catalyst.The lamellar nano-crystals grown on cotton fabric have been characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),thermal gravimetric analysis(TGA)and optical wavelength spectrometer.The XRD studies revealed that Mg(OH)2 was lamellar.The SEM studies showed that the lamellar crystals were located like vertical fish scales on the surface of cotton fabric.The TGA studies indicated that the growth of Mg(OH)2 on modified cotton fabric could be applied to the filed of fire-proof.Through optical wavelength scanning,the radioprotection property was observed.The best growth condition of Mg(OH)2 lamellar nano-crystals was as follows:the cotton with Mg(OH)2 seeds were put into the system until pH value achieved 9.68 by adding MgCl2 and NH3·H2O solutions;then the secondary crystallization of Mg(OH)2 on cotton was kept for 30 days, when the surface were covered with Mg(OH)2 lamellar nano-crystals.The hydrothermal treatment was undergone with Mg(OH)2 saturated solution at 80℃for 3 hours,and Mg(OH)2 lamellar nano-crystals were transferred from veritical to horizontal.
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