Sulfamic Acid Stabilizer for Halogen Biocide in Papermaking
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Solution Overview
Problem
Biological activity in process streams, particularly in papermaking processes, is challenging due to the instability of oxidant biocides, leading to ineffective microbial control, corrosion of equipment, and adverse effects on paper quality and production efficiency, with existing stabilization methods being either ineffective or too rigid in dosage requirements.
Innovation Solution
A composition comprising a halogen source, urea, and an additional halogen stabilizer, optionally with an alkali to maintain a pH greater than 10, which includes a mixture of sulfur-bearing species like sulfamic acid and nitrogen stabilizers, such as ammonium sulfate, to enhance the persistence and compatibility of halogen biocides in papermaking processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidant biocides are used to control microbial activity, then microbial control effectiveness is improved, but biocide stability deteriorates causing rapid oxidation and loss of effectiveness
Solution Approach 1:
The patent introduces stabilizing agents (intermediary substances) that mediate between the halogen biocide and the process water system. These stabilizers form complexes with halogen, slowing oxidation rates and extending biocide effectiveness while maintaining microbial control capability.
Solution Approach 2:
The patent modifies the chemical parameters of the biocide system by adjusting pH (maintaining >10), halogen to stabilizer ratios, and oxidation-reduction potential. These parameter changes optimize the balance between biocide stability and microbial control effectiveness.
2Reliability
If repeated applications of oxidant biocides are made to maintain microbial control, then microbial suppression is improved, but adverse effects on paper additives and equipment corrosion increase
Solution Approach 1:
The patent establishes continuous biocide stabilization through the formation of long-lasting halogen-stabilizer complexes that provide sustained microbial control without requiring repeated high-dose applications, thereby reducing cumulative harmful effects on equipment and paper additives.
Solution Approach 2:
By maintaining pH >10 and optimizing halogen-to-stabilizer ratios, the patent creates conditions where biocides act more selectively against microorganisms while minimizing non-specific reactions with paper additives and equipment materials.
3Reliability
If higher levels of halogen biocides are added to combat biological activity spikes, then microbial control is improved, but halogen by-product formation and environmental impact worsen
Solution Approach 1:
Stabilizing agents act as intermediaries that control the release and reaction of halogen, enabling effective microbial control at lower halogen concentrations by preventing premature oxidation and by-product formation while maintaining sufficient biocidal activity.
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 sustained microbial control with reduced chlorine usage, minimizing halogen by-product formation and equipment corrosion, while maintaining the effectiveness of paper additives, offering a flexible and environmentally friendly biocide delivery protocol.
Implementation Method 1
Use of sulfamic acid or its salts as stabilizers especially in combination with ammonium salt and/or ammine for bleach or other halogen containing biocides
Implementation Method 2
optionally an alkali in a concentration sufficient to provide said composition with a pH of greater than 10
Implementation Method 3
a mixture of sulfur-bearing species like sulfamic acid and nitrogen stabilizers, such as ammonium sulfate
Implementation Method 4
Oxidant biocides such as peroxide acid and halogen chemicals like sodium hypochlorite have been widely used in the pulp and paper industry
Data Source
AI summary
The invention is directed to compositions and methods of their use as effective biocidal agents for water streams. The composition comprises a halogen source, halogen stabilizers containing a sulfur bearing species and ammonium salts/urea, and an alkali. The sulfur bearing species includes sulfamic acid or its salt equivalent. By having optimized mixing ratio of halogen to stabilizer and that of ammonium salts to sulfamic acid or sulfamate, a synergistic effect occurs which both increases the efficacy of the composition as a biocide and it avoids adverse impacts on other chemicals that are present in the water stream. Best of all the composition is easy to form and easy to introduce into a water stream of concern. Its introduction can be as simple as mixing two containers of reagent prior to introduction to the water process stream.