Preparation And Application Of Modified Ground Tire Rubber

With rapid development of the industry and economy,the annual production of waste tire rubber has increased significantly in recent years,which threaten both the human health and environment.Waste tire rubber is non-biodegradable and produces much toxic gas during combustion,thus how to dispose it correctly has become imperative.From the standpoint of environmental friendliness and economic efficiency,the main way to recycle waste tire rubber is processing it into rubber powder.Ground tire rubber is considered to have butadiene units and isoprene units,and double bonds within which are beneficial for chemical modification.The metal plating,mining and fertilizer industries are rapidly developing,due to which serious environmental problems occur.Therefore,heavy metal-containing water has already become a social problem to be solved urgently.Amo ng many metal ions,lead ions are non-biodegradable and tend to accumulate in living organisms.Moreover,lead-contaminated wastewater has caused wide public concern since trace levels of lead would endanger aquatic life and human beings.Hence,it is nece ssary to take appropriate measures to eliminate or reduce the lead-related water contamination.Recently,thermal-chemical treatment of waste rubber tires as activated carbon adsorbent has caused wide public concern.But the by-product produced in the pyrolysis process of preparation will endanger the environment.More importantly,more energy is needed for the production.This paper tries to prepare modified ground tire rubber merely by chemical treatment and use it to adsorb Pb²⁺ from aqueous solution.Polyurethane is a polymer containing urethane segment repetitive structure as the constructional repeat unit was synthesized by the chemical reaction between isocynate and polyhydric alcohols.Today,rigid polyurethane foam servers as insulation materials due to its performance advantages,such as low thermal conductivity,high specific strength and low density.However,there are few reports about the research on the insulation materials which were made of soft polyurethane foam.In this work,we prepared a composite of soft polyurethane foam and ground tire rubber in catalyst–free condition.And we also measured the thermal conductivity,tensile strength and elongation at break of the materials.In this paper,the lysine modified ground tire rubber was successfully prepared by the chemical modification using ground tire rubber as raw materials.The adsorption ability was investigated.Furthermore,a composite of soft polyurethane foam and ground tire rubber was prepared in catalyst –free condition.The mechanical properties were further evaluated.The detailed work can be summarized as following:?1?After treated with toluene,modified ground tire rubber was prepared through the reaction with bromine,followed by a lysine reaction to develop the carboxylic and amino groups on the rubber.The properties of the samples have been studied.The average particle sizes of the modified ground tire rubber was 252.9 ?m.Also,the surface area as well as the porosity of it is comparatively higher than that of the raw ground tire rubber,indicating that the modified ground tire rubber has great potential for the Pb²⁺ removing.?2?The modified ground tire rubber was used to remove Pb²⁺ from aqueous solution.Effects of pH value,adsorbent dose and contact time on the adsorption have been discussed.In addition,the adsorption kinetics behavior of the process was discussed.The results showed that the optimal pH value for Pb²⁺ removing was about 5-7;the percentage of Pb²⁺ removal arrived at 92% with the modified ground tire rubber of 1.0 g/L.Under the optimal conditions,the equilibrium was obtained at around 380 min.Additionally,the experimental data was found to fit the pseudo-second-order model well.?3?Soft polyurethane foam was prepared by polyethylene glycol 4000,polyethylene glycol 200,phenyl isocyanate,foam stabilizer and foaming agent in catalyst–free condition.Moreover,based on the preparation process of original material,the composite of soft polyurethane foam and ground tire rubber was prepared by adding tire rubber powders.The apparent density,tensile property and thermal conductivity of all kinds of materials were further evaluated.The effects of rubber powders on the product performance were also investigated.