Study On Preparation Of Superplasticizer From Concentrated 2-Naphthol High-salt Wastewater

Sodium salt of sulfonated naphthalene-formaldehyde condensates（PNS）is an important component of naphthalene superplasticizer.PNS is widely used in construction industry because of their high water reduction rate,excellent adaptability of cement and other characteristics.Generally,2-naphthol is a vital intermediate in organic synthesis,dyes and pigments.However,a large amount of high salinity and toxicity waste liquids produced in the production process of 2-naphthol have become the main source of water environmental pollution in our country.The PNS superplasticizer was successfully synthesized from concentrated 2-naphthol high-salt wastewater（Black Liquor）as raw material.Firstly,the reaction parameters,such as total acidity of sulfuric acid,condensation time,condensation temperature,molar ratio of formaldehyde to naphthalene sulfonic acid and inlet temperature of formaldehyde,were investigated by series experiments to understand the water-reducing properties of products and the optimal reaction parameters were given.Meanwhile,the order of influence factors of making water reducer was obtained by orthogonal experiments.Then,Na₂SO₄·10H₂O as the by-products were obtained from PNS liquor through refrigeration for sulfate removal process.The effect of cooling rate and final temperature were systematically discussed to get the high efficient naphthalene water-reducing agent and the large size of Na₂SO₄·10H₂O crystals.Further,the performance of PNS superplasticizer was tested.Adding 1.0%superplasticize into cement mortar,the system displayed better disparity,mobility and the PNS water reducing agent showed obvious retarding effect.Finally,the industrial production plan of PNS superplasticizer from 2-naphthol Black Liquor were presented,and the occupational hazard factors and basic protective measures in the production process were clarified explicitly,which laid theoretical and experimental foundation of the industry production of PNS superplasticizer.Figure19;Table15;Reference 49.