DMF Recovery From Salt-Laden Aqueous Streams by Extraction
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Solution Overview
Problem
Existing processes for recovering N,N-Dimethylformamide (DMF) from aqueous process streams, particularly those containing inorganic salts and high molecular weight organic compounds, are inefficient, leading to high waste volumes and environmental emissions, as DMF is difficult to separate due to its high boiling point and the presence of salts.
Innovation Solution
A process involving pH adjustment of the aqueous stream to basic values using bases like KOH or NaOH, followed by extraction with chloroform, and subsequent distillation to recover DMF, effectively separating it from salts and organic impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DMF is recovered from aqueous process streams containing inorganic salts and high molecular weight organic compounds using conventional extraction and distillation methods, then some DMF recovery is achieved, but the recovery efficiency is low and the process is cumbersome and costly
Solution Approach 1:
The patent introduces a specific extractant system (mixture of chlorinated hydrocarbons and aromatic hydrocarbons) as an intermediary substance to facilitate the separation of DMF from the aqueous process stream. This extractant acts as a mediator that selectively transfers DMF from the aqueous phase to the organic phase, enabling efficient recovery even in the presence of inorganic salts and high molecular weight organic compounds that would otherwise complicate the separation process
Solution Approach 2:
The patent optimizes specific parameters of the extraction process including the ratio of extractant to aqueous phase (1:1 to 3:1 by volume), the composition of the extractant mixture (chlorinated hydrocarbon component at 50-95% by volume), and process conditions to maximize DMF recovery efficiency while simplifying the overall process compared to conventional methods
2Manufacturing precision
If conventional extractants with large boiling point differences from DMF are used, then separation is easier, but the extractants are less effective for DMF recovery from aqueous streams containing salts and organic compounds
Solution Approach 1:
The patent employs a composite extractant system consisting of a mixture of chlorinated hydrocarbons (such as dichloromethane, chloroform, or 1,1,1-trichloroethane) and aromatic hydrocarbons (such as benzene, toluene, or xylene). This composite extractant combines the advantages of both components: the chlorinated hydrocarbon provides high extraction efficiency for DMF from aqueous streams, while the aromatic hydrocarbon contributes to selective separation and achieves the desired boiling point difference for easy distillation. The synergistic effect of this mixture enables both high recovery rates (>98%) and high purity (>95%) of DMF
Solution Approach 2:
The patent carefully adjusts the composition ratio of the extractant components (chlorinated hydrocarbon at 50-95% by volume) and the extractant-to-feed ratio (1:1 to 3:1 by volume) to optimize the balance between extraction efficiency and separation ease, achieving both high productivity and manufacturing precision
3Ease of manufacture
If DMF is not recovered from mother liquor, then the process is simpler, but waste disposal becomes troublesome and costly with high environmental impact
Solution Approach 1:
The patent implements a DMF recovery process that transforms the waste disposal problem into a resource recovery opportunity. By applying liquid-liquid extraction followed by distillation, the process retrieves DMF from the mother liquor, allowing it to be reused in subsequent batches. This approach eliminates the need for costly and environmentally harmful waste incineration or landfilling, while the simplified two-step process maintains ease of manufacture
Solution Approach 2:
The recovered DMF is reused in the same chemical process for which it was originally used, creating a self-service cycle where the solvent serves its function again and again. This reduces the need for fresh DMF purchases and minimizes waste generation, making the process both environmentally friendly and economically beneficial
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves high yield and purity of DMF recovery, allowing for its reuse in chemical processes, significantly reducing waste volume and emissions, with recovery rates exceeding 98% and purity exceeding 95%, even in the presence of inorganic salts and high molecular weight organic compounds.
Implementation Method 1
pH adjustment of the aqueous stream to basic values using bases like KOH or NaOH
Implementation Method 2
extraction with chloroform, and subsequent distillation to recover DMF, effectively separating it from salts and organic impurities
Implementation Method 3
subsequent distillation to recover DMF
Data Source
AI summary
The invention relates to an improved process for recovering N,N-Dimethylformamide (DMF) from an aqueous process stream by adjusting the pH, extracting with Chloroform and subsequent distillation/rectification.