Formation Of Diatomite-Based Composites And Their Applications In Papermaking

Micron scale inorganic particles can be used as paper filler,coating pigment,retention filter aid and resin control agent in the papermaking.It has important use value.Diatomite is a non-metallic mineral,and its main component is amorphous silica,which has unique pore structure and function characteristics.Diatomite has been applied in papermaking.However,its application still has some limitations.The potential of the diatomite is need to be tapped.In this work,the research work mainly includes two aspects:(1)The modification of diatomite was investigated using modifier for improvement of diatomite bondability,optical properties,application performance.The efficient application f-oundation of diatomite was founded in special paper.(2)The unique pore structure of diatomite particles was utilized and the interaction between ions.The application of modified diatomite in treatment wastewater to remove pollutants was investigated.It opens up a new way for the utilization of diatomite.(?)Preparation and application of modified diatomiteDiatomite particles were modified with starch-fatty acid,sodium hexametaphosphate/cationic starch,sodium dodecyl sulfate/polyethyleneimine,octadecyl trimethylammonium chloride,cationic starch/concentrated stearate/calcium chloride,sodium carbonate/calcium chloride.The bondability,optical properties and adsorption efficiency of the modified diatomite were investigated.The surface morphology,Zeta potential,particle size and FTIR spectroscopy characteristic of the modified diatomite were investigated,and the application performances of the modified diatomite were evaluated by physical properties of paper and filler retention.The characteristics and application performances of several kinds of composite modified diatomite were compared.Diatomite particles were modified with sodium hexametaphosphate/cationic starch,polyethyleneimine,octadecyl trimethyl ammonium chloride.The Zeta potential,bondability,retention of the modified diatomite particles were increased.The handsheet filled with modified diatomite had higher strength properties.Diatomite particles were modified with starch-fatty acid.Modified diatomite filler was prepared.Strength performance of the handsheet filled with modified diatomite was improved.However,the bulk of the handsheet was slightly lower.Diatomite particles were modified with cationic starch/sodium stearate.Modified diatomite filler was prepared.The modification effect and performance were evaluated.The bulk of the handsheet filled with modified diatomite was improved.However,the whiteness of the handsheet was slightly lower.Diatomite particles were modified with calcium chloride and sodium carbonate.Modified diatomite filler was prepared.The modification effect and oerformance were evaluated.The whiteness of the handsheet filled with modified diatomite was improved.On the whole,diatomite particles were modified with sodium dodecyl sulfate/polyethyleneimine.Modified diatomite filler was prepared.The modified diatomite was proved to be comparatively competitive,as far as their use in papermaking is taken into consideration.Zeta potential,bondability,application efficiency of the modified diatomite had the best performance.The Zeta potential of the surface of the modified diatomite particles was changed from electronegativity to electropositivity,The Zeta potential of modified diatomite was higher 25 mV when polyethyleneimine equilibrium concentration was 0.24 g·L-1.Compared with the handsheet filled with unmodified diatomite,the handsheet filled with modified diatomite had higher strength properties.The strength index of the handsheet with modified diatomite filler was 34.9%higher than the handsheet with unmodified diatomite.The retention of modified diatomite filler was 16%higher than unmodified diatomite when filler dosage was 40%.The drainability of papermaking furnish was improved efficiently.The anionic trash in the papermaking system was anchored efficiently,and the cationic demand of papermaking furnish decreased over 85%.(?)Preparation and application of modified diatomite adsorbentDiatomite particles were modified with cationic polyacrylamide or chitosan.Modified diatomite adsorbent was prepared.The modification effect and performance were evaluated.The CODcr removal rate was higher 80%when the cationic polyacrylamide modified diatomite dosage was 350 mg/L and the time was 2 h.The removal rate of turbidity is more than 95%,and the chroma removal rate was 100%.The modified diatomite has the best performance when chitosan dosage was 6%,pH was 8,and chitosan concentration was 5-6 g/L.The modification methods of two kinds of modified diatomite adsorbents were compared.The method of composite modification based on cationic polyacrylamide was simpler and easier.The differences of modified diatomaceous adsorbent in removal ratio of turbidity,in CODcr removal ratio,adsorption time,turbidity removal ratio and treatment temperature were compared.It can be seen that cationic polyacrylamide modified diatomite was used for wastewater treatment and has good application prospect.