Aqueous Polysulfide Composition with Low Thiosulfate
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Solution Overview
Problem
Existing polysulfide compositions generate substantial amounts of thiosulfates and hydrogen sulfide (H2S) as by-products, which are undesirable in industrial applications, particularly in water treatment and metal capturing processes.
Innovation Solution
Developing an aqueous polysulfide composition with at least 30% by weight of polysulfides and no more than 5% by weight of thiosulfate anions, achieved by reacting a sulfide salt with elemental sulfur, thereby minimizing thiosulfate production and maintaining a pH of at least 10 to prevent H2S gas formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polysulfides are produced by reacting hydroxide with sulfur, then polysulfides are formed, but substantial amounts of thiosulfates are generated as by-products
Solution Approach 1:
The patent changes the reaction parameters by using sulfide salts instead of hydroxides as the starting material. This parameter change fundamentally alters the reaction pathway, producing polysulfides while minimizing thiosulfate formation. The use of sulfide salts (such as sodium sulfide or calcium sulfide) reacting with sulfur yields polysulfides with thiosulfate content at most 5% by weight, compared to substantial thiosulfate generation in conventional hydroxide-based processes.
2Quantity of substance
If traditional polysulfide processes are used, then polysulfides are produced, but H2S vapor pressure and toxic by-products are generated
Solution Approach 1:
The patent employs sulfide salts as stable, non-volatile starting materials that replace the problematic H2S gas handling in traditional processes. The sulfide salts serve as a safer, more controllable reagent that eliminates H2S vapor pressure issues while maintaining polysulfide production efficiency. This substitution of reagents fundamentally resolves the toxicity problem.
3Object-affected harmful factors
If water based polysulfide compositions are used, then environmental safety is improved, but solubility and efficiency are limited
Solution Approach 1:
The patent creates composite aqueous polysulfide compositions that combine polysulfides with specific auxiliary substances to enhance solubility and stability in water. These compositions maintain the environmental safety of water-based systems while achieving at least 30% by weight polysulfide concentration through optimized formulation. The composite nature allows high polysulfide content to be maintained in aqueous solution without precipitation or decomposition.
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
The solution provides a higher concentration of reactive polysulfides with reduced impurities, enhancing the efficiency and safety of polysulfide compositions in applications such as metal capturing and flotation processes, while minimizing environmental concerns associated with H2S production.
Implementation Method 1
reacting a sulfide salt (c) with elemental sulfur to form the one or more polysulfide salts (d)
Data Source
AI summary
An aqueous polysulfide composition comprises one or more inorganic polysulfides, wherein the amount of polysulfides in the composition is at least 30% by weight, preferably at least 35% by weight, more preferably at least 40% by weight, and wherein the amount of thiosulfate anions in the composition is at most 5% by weight, relative to the total weight of the composition. In one embodiment the weight ratio of polysulfides to thiosulfates in the aqueous composition is from 55/1 to 1.5/1. In another embodiment, the aqueous polysulfide composition has a pH of at least 10. A process for preparing an aqueous polysulfide composition comprises reacting a sulfide salt (c) with elemental sulfur to form one or more polysulfide salts. The compositions have many uses and are in particular useful in metal capturing, cyanide scavenging, soil remediation, water treatment, petroleum processing, leather processing, and making of paper pulp.