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Pretreatment method for rectifying and recovering dimethyl formamide (DMF) waste liquid of polyurethane (PU) synthetic leather

A synthetic leather and pretreatment technology, applied in fractionation and other directions, can solve the problems of large and high-concentration wastewater, increased energy consumption, DMF loss, etc., to achieve good results, reduce production costs and energy consumption, and reduce energy consumption.

Inactive Publication Date: 2014-03-12
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The tower washing process will cause DMF loss and produce a large amount of high-concentration wastewater. At the same time, frequent tower washing (starting and stopping) will also cause problems such as increased energy consumption

Method used

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  • Pretreatment method for rectifying and recovering dimethyl formamide (DMF) waste liquid of polyurethane (PU) synthetic leather

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Since many processes in the production of PU synthetic leather will generate DMF waste liquid, it is necessary to collect the DMF waste liquid discharged from each process uniformly. 10 tons of DMF waste liquid from the waste water storage tank of the PU synthetic leather production line is sent through the infusion pump into the coarse filter made of 100-mesh stainless steel mesh for primary separation, and the particles with a particle size ≥ 154 μm are removed to ensure the quality of the subsequent sedimentation separator. Safe operation and improved operation capacity; the DMF waste liquid after primary separation enters the microfiltration membrane separation device for secondary separation to remove sol-like solid suspended particles with a particle size ≥ 1 μm, and basically removes particles with a particle size of 1~ Particles of 154 μm; the self-priming pump of the membrane separation device adopts intermittent working mode: work for 5 hours, pause for 5 minut...

Embodiment 2

[0025] 15 tons of DMF waste liquid from the waste water storage tank of the PU synthetic leather production line is sent through the infusion pump into the coarse filter made of 150-mesh stainless steel mesh for primary separation, and the particles with a particle size ≥ 100 μm are removed to ensure the quality of the subsequent sedimentation separator. Safe operation and improved operation capacity; the DMF waste liquid after primary separation enters the microfiltration membrane separation device for secondary separation to remove sol-like solid suspended particles with a particle size ≥ 1 μm, and basically removes particles with a particle size of 1~ Particles of 100 μm; the self-priming pump of the membrane separation device adopts intermittent working mode: work for 7 hours, pause for 10 minutes, and cycle repeatedly. During the suspension period of the self-priming pump, backwash with DMF waste liquid after microfiltration, the backwash pressure is about 0.1MPa, and the ...

Embodiment 3

[0028] 15 tons of DMF waste liquid from the waste water storage tank of the PU synthetic leather production line is sent through the infusion pump into the coarse filter made of 200-mesh stainless steel mesh for primary separation, and the particles with a particle size ≥ 74 μm are removed to ensure the quality of the subsequent sedimentation separator. Safe operation and improved operation capacity; the DMF waste liquid after primary separation enters the microfiltration membrane separation device for secondary separation to remove sol-like solid suspended particles with a particle size ≥ 1 μm, and basically removes particles with a particle size of 1~ Particles of 74 μm; the self-priming pump of the membrane separation device adopts intermittent working mode: work for 8 hours, pause for 20 minutes, and cycle repeatedly. During the suspension period of the self-priming pump, backwash with the clean liquid after microfiltration, the backwash pressure is about 0.2MPa, and the ba...

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Abstract

The invention discloses a pretreatment method for rectifying and recovering dimethyl formamide (DMF) waste liquid of polyurethane (PU) synthetic leather. The pretreatment method comprises the following steps: (1) pumping the DMF waste liquid from a waste water storage tank of a PU synthetic leather production line into a coarse filter consisting of a stainless steel filter screen by using an infusion pump and performing first-stage separation to obtain coarse filtration DMF waste liquid; and (2) allowing the coarse filtration DMF waste liquid obtained by first-stage separation to enter a microfiltration hollow fiber membrane separation device and performing second-stage separation to obtain a DMF fine solution for rectification and recovery. By the pretreatment method for rectifying and recovering the DMF waste liquid of the PU synthetic leather provided by the invention, the problems of high pollution and high energy consumption of rectification and recovery of the DMF waste liquid in the PU synthetic leather industry are solved; the aims of energy saving and emission reduction in the production process of the PU synthetic leather are fulfilled, and economic benefit, social benefit and environmental benefit are organically unified.

Description

(1) Technical field [0001] The invention relates to a pretreatment method of waste liquid, in particular to a pretreatment method for rectification and recovery of N,N-dimethylformamide (DMF) waste liquid in the PU synthetic leather industry. (2) Background technology [0002] The polyurethane (PU) resin used in the production of PU synthetic leather usually uses DMF as a solvent. In the PU synthetic leather wet production line, PU resin is coated on the leather base cloth, and then enters the coagulation tank, during which DMF seeps out and dissolves in water, and after reaching a certain mass concentration (about 20%), it is discharged into the DMF waste liquid storage Can. In order to eliminate the impact of waste liquid on the environment and reduce production costs, DMF waste liquid must be rectified and recovered. Suspensions from PU resin and leather base cloth (wood flour / short fiber, 1500-2500mg / L) and polyurethane resin oligomers (8-10g / L) exist in DMF waste liqu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D3/14
Inventor 林春绵王美华魏秀珍
Owner ZHEJIANG UNIV OF TECH
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