Method for recycling sodium alginate from reactive dye printing wastewater by virtue of calcium coagulation-chelating agent process

Abstract

The invention discloses a method for recycling sodium alginate from reactive dye printing wastewater by virtue of a calcium coagulation-chelating agent process. The method is characterized by firstly chelating sodium alginate in reactive dye printing wastewater with calcium ions to form calcium alginate precipitates, then adding a calcium ion chelating agent which has a stronger chelating ability to the calcium ions than the chelating ability of calcium alginate to capture the calcium ions from calcium alginate, and transforming into sodium alginate to achieve the aim of recycling sodium alginate. The method specifically comprises the following steps: adding a calcium salt into the reactive dye printing wastewater under the condition of stirring to form the calcium alginate precipitates, and filtering and collecting; adding a certain quantity of the calcium ion chelating agent into recycled calcium alginate, and reacting for a period of time to obtain sodium alginate; and separating out sodium alginate by adding ethanol. The method disclosed by the invention has the advantages that the method for recycling sodium alginate from the reactive dye printing wastewater can be used for saving the production cost, achieves the cyclic utilization of resources, and can also be used for reducing the content of organic matters in the wastewater and reducing the burden of wastewater treatment.

Description

technical field [0001] The invention discloses a sodium alginate recovery technology, in particular to a recovery method for sodium alginate in reactive dye printing wastewater. Background technique [0002] Sodium alginate is the most ideal paste for reactive dye printing of pure cotton fabrics. It has strong paste rate, good permeability, non-reducibility, wide range of applicable pH values, and does not react with reactive dyes. It is easy to wash and dye on. High dyeing rate, good fabric feel. In recent years, due to the continuous increase in the number of printed products, sodium alginate has been widely used in the textile printing and dyeing industry; due to the limited production of kelp and brown algae, the main raw materials for the production of sodium alginate, and the production technology of sodium alginate is constantly improving. However, acid coagulation-acidification method, calcium coagulation-acidification method and calcium coagulation-ion exchange met...

AI Technical Summary

Problems solved by technology

[0003] There are very few studies on recovering sodium alginate from printing and dyeing wastewater. Patent CN101381419A discloses a method for extracting sodium alginate from reactive dye printing wastewater. It is characterized in that according to the production method of sodium alginate, acid coagulation-acidification method, calcium Coagulation-acidification method and calcium coagulation-ion exchange method are three methods to extract sodium alginate in reactive dye printing wastewater. Among them, calcium coagulation-acidification method is to add calcium chloride to obtain calcium alginate precipitation, and then acidify it into Alginic acid, and then neutralized with soda ash to obtain sodium alginate, the recovery process of this method is complicated, which will inevitably cause waste of cost and resources

[0004] At present, the method of using the calcium coagulation-chelating agent method to reclaim sodium alginate from reactive dye printing wastewater has not been reported in the literature. The calcium coagulation-chelating agent method refers to the use of effective calcium ion chelating agents, utilizing calcium ion chelating A method for converting calcium alginate into sodium alginate due to the difference in the ability of acids to chelate calcium ions