Preparation and Coagulation Behavior of a Novel Multiple Flocculant Based on Cationic Polymer, Hydroxy Aluminum, and Clay Minerals

Feng-Shan Zhou,Lin Zhou,Yang Liu,Xi Wang

doi:10.1155/2015/581051

Abstract

Cationic polymer, hydroxy aluminum, and clay minerals are three flocculants with different action mechanisms and a more cost-efficient multiple flocculant can be prepared by compositing them through appropriate technology. All of attapulgite (ATP), clay minerals containing magnesium, aluminum, and silicate, are porous environmental mineral material with good absorbability and have found wide applications in industrial sewage treatment. With polyaluminum chloride (PAC), poly(dimethyl diallyl ammonium chloride) (PDMDAAC), and attapulgite (ATP) clay being the main raw materials, multiple flocculant CMHa (liquid) with good storage stability was prepared and its optimized blending mass percent was PDMDAAC of 2%-3%, ATP of 4%–6%, and PAC of 20%–30%. The liquid poly(dimethyl diallyl ammonium chloride) (PDMDAAC) was firstly loaded on solid material in kneader and then mixed in certain proportion with PAC and ATP to prepare solid CMHa convenient for storage and transportation. The optimized mass ratio is PAC : ATP : PDMDAAC = 80 : 10 : 2.4. When this multiple flocculant was used to treat domestic sewage, coal washing sewage, dyeing wastewater, and papermaking wastewater, its equivalent dosage was just 50% of PAC, while overall production cost has been reduced to about 40%, viewing showing broad application prospect.

Highlights

Flocculants have found wide application due to their good coagulation and purification behavior, low price, and convenience and have been the most widely used water treatment agent with the largest consumption [1, 2].Micromolecular inorganic salt flocculants, for example, aluminium chloride (AlCl3⋅6H2O), ferrous sulfate (FeSO4⋅7H2O), and ferric chloride (FeCl3⋅H2O), have advantage in low cost but their alum grains are small and are strongly corrosive, so they are generally replaced by inorganic polymer flocculants
By combining structural features and flocculation performance of organic cationic polymer (C), inorganic hydroxy aluminium (Ha), and clay mineral (M), this paper aims at developing a multiple flocculant CMHa with good performance and low cost
Blend polyaluminum chloride (PAC), cationic polymer, and hydrated mineral suspension in various proportions at first and the mixture was stirred at certain temperature to form uniform solution, that is, liquid CMHa sample

Summary

Introduction

Micromolecular inorganic salt flocculants, for example, aluminium chloride (AlCl3⋅6H2O), ferrous sulfate (FeSO4⋅7H2O), and ferric chloride (FeCl3⋅H2O), have advantage in low cost but their alum grains are small and are strongly corrosive, so they are generally replaced by inorganic polymer flocculants. Polyaluminum chloride (PAC), polyferric sulfate (PFS), polyferric chloride (PFC), and polyaluminium ferric chloride (PAFC) are popular inorganic polymer flocculants. Speaking, inorganic polymer flocculants have better flocculation performance and cheaper than organic flocculants; their storage stability is poor and will produce plenty of sludge; it is difficult for subsequent treatment [1, 3]. Organic flocculants have advantage in low dosage, fast flocculation velocity, being affected little by coexisting salts, pH of medium, and environment temperature, small amount of sludge, and good decolorization performance, but they are costly and their hydrolyzed or degraded products are toxic. Organic polymer flocculant is classified as natural and multiple [3, 4]

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