Nitrogen-Doped Sorbent for Chloramine Removal
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Solution Overview
Problem
Existing methods for producing sorbent materials with high surface areas and catalytic properties, such as activated carbons, suffer from the loss of nitrogen-containing precursors during high-temperature activation processes, which reduces their catalytic activity and effectiveness in removing harmful compounds from water.
Innovation Solution
A novel process involving the oxidation of sorbent material feedstocks with specific oxidizing agents followed by the addition of reduced nitrogen-containing precursors and heating under an inert atmosphere to form sorbent materials with enhanced nitrogen retention and catalytic activity, specifically targeting chloramine and chlorine destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If high-temperature activation and oxidation processes are used to create high surface area sorbent materials, then the surface area and porosity are improved, but the nitrogen-containing precursors are lost and catalytic activity is reduced
Solution Approach 1:
The nitrogen-containing precursor is incorporated into the sorbent material structure before the high-temperature activation process. This preliminary incorporation ensures that nitrogen is present in the carbon matrix prior to oxidation, allowing it to form stable nitrogen-doped structures that resist removal during subsequent activation steps
Solution Approach 2:
The activation process is conducted in an inert or controlled atmosphere rather than pure oxygen or air. This controlled environment reduces the oxidative removal of nitrogen while still allowing sufficient oxidation to develop the desired surface area and porosity characteristics
2Quantity of substance
If high-temperature activation processes are used to gasify surface carbon and create pores, then the porosity and surface area are improved, but the catalytic properties are reduced due to nitrogen removal
Solution Approach 1:
The activation temperature, time, and atmospheric composition are carefully controlled and optimized to achieve the desired porosity while minimizing nitrogen loss. By adjusting these parameters, the process creates sufficient pores for high surface area while preserving enough nitrogen for catalytic activity
Solution Approach 2:
The sorbent material is designed as a composite structure with nitrogen-doped carbon phases embedded in the porous matrix. This composite approach allows the material to simultaneously exhibit high porosity for adsorption and nitrogen-rich domains for catalytic function
3Area of stationary object
If oxygen-based activation gases are used at high temperatures, then the surface area is improved through carbon gasification, but the nitrogen precursor is removed reducing performance
Solution Approach 1:
The activation process uses an inert or controlled atmosphere instead of pure oxygen or air. This reduces the oxidative removal of nitrogen while still allowing sufficient oxidation to develop the desired surface area and porosity characteristics
Solution Approach 2:
The strong oxidizing power of oxygen at high temperatures, which normally causes nitrogen loss, is converted into a benefit by carefully controlling the atmosphere and timing. The oxidation is sufficient to create pores and surface area but limited enough to preserve catalytic nitrogen, turning a potentially harmful effect into a controlled useful process
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 process results in sorbent materials with improved chloramine and chlorine destruction capabilities, as measured by higher chloramine destruction numbers (CDN) and nitrogen edge concentration, maintaining nitrogen content and enhancing catalytic performance.
Implementation Method 1
oxidizing the sorbent material feedstock with an oxidizing agent
Implementation Method 2
heating the oxidized sorbent material feedstock and nitrogen-containing precursor to a temperature of at least about 400° C. under an inert atmosphere
Data Source
AI summary
Sorbent materials are described that have enhanced performance in removing chlorine and chloramine, among other toxic compounds. The sorbent materials are formed by a process which includes steps of oxidation using an oxidizing agent, adding a nitrogen-containing compound, and calcining the sorbent.