Preparation And Study On The Coagulant Of Chitosan/Polysilicate Aluminum Ferric Composite Kaolin

Water treatment has become a key point of environmental protection around the world.Meanwhile,the rapid economic development in China has brought about more and more discharge of industrial wastewater and domestic sewage,thus making water pollution an increasingly severe issue.To address this issue,coagulant sedimentation is one of the most commonly adopted methods for water treatment,of which coagulant is the key.Thus,it is of great significance to develop a highly effective,non-toxic,and low-cost new type of coagulant.This article analyzes the method of developing coagulant using fly ashes,crab's hulls,and kaolin as the raw materials.Firstly,polysilicate aluminum ferric is developed out of fly ashes by using the copolymerization method;abandoned crab's hulls are washed,de-hydrated,smashed,decalcified,de-proteinated,and de-acetylated to develop chitosan;meanwhile,kaolin isalkalimodified and thermally activated to develop the kaolin carrier.Then,chitosan,polysilicate aluminum ferric and kaolin carriersare combinedbased on a certain mass ratio to get a new type of chitosan/polysilicate aluminum ferric composite kaolin coagulant.This article explored the preparation condition for and mass ratio of chitosan/polysilicate aluminum ferric composite kaolin coagulant through single factor experiments and orthogonal tests.The experiments concluded that the condition for developing chitosan/polysilicate aluminum ferric composite kaolin coagulant was the pH of2.0,temperature of 70?,mass ratio of 2 to 1 between chitosan and polysilicatealuminum ferric,kaolin dosage of 7.0g/L,all of which were combined,stirred,aged,centrifuged,dried,and ground to develop the chitosan/polysilicate aluminum ferric composite kaolin coagulant.Its structure was represented through SEM.The STA6000 IR tests proved the containment of-OH,-NH3,and Al-OH-Fe in the coagulant.Through the treatment of domestic sewage,dyeing wastewater and heavy metal wastewater using the chitosan/polysilicate aluminum ferric composite kaolin coagulant,this article examined the influence of dosage and pH value,effectiveness of this new type of coagulant,and its coagulant mechanism.The outcomes showed that:when the dosage of chitosan/polysilicate aluminum ferric composite kaolin coagulant was 40mg/L and the pH was 8,the removal rate of COD and turbidity in domestic sewage was as high as 85%and92%,respectively;when the dosage was 0.5g/L and the pH was 6,then the de-colorization ratio of the simulated dyeing wastewater direct black solution maximized at 99%.Regarding the treatment of metal wastewater,the removal rate of Cr⁶⁺,Cu²⁺was 95%and 97%respectively when the dosage was 1.3g/L and the pH was 7.Thus,the chitosan/polysilicate aluminum ferric composite kaolin coagulant turns out to be a highly effective green composite coagulant,which possessed the features of organic flocculants,inorganic flocculants,and absorbents,with high effectiveness in wastewater treatment and wide application.