Abstract:

This study focuses on the selection and analysis of magnets for use in magnetic stirring photocatalytic reactors, which are pivotal in enhancing the efficiency of photocatalytic reactions. The aim is to identify optimal magnet types that can effectively facilitate stirring within the reactor while maintaining stability and durability under various experimental conditions. Through a comprehensive evaluation of magnetic properties, stirring performance, and material compatibility, this work provides insights into the design and optimization of magnetic stirring systems for photocatalytic applications.

1. Introduction

Photocatalytic reactors are widely used in environmental remediation, water treatment, and energy conversion processes. Among various reactor designs, magnetic stirring photocatalytic reactors (MSPRs) stand out due to their ability to provide efficient mixing and mass transfer without the need for mechanical stirrers, which can potentially interfere with light penetration and catalyst activity. The choice of magnet is crucial in determining the stirring efficiency, reactor performance, and overall system reliability. This paper presents a systematic approach to selecting and analyzing magnets for MSPRs, based on their physical and chemical properties, as well as their impact on reactor performance.

2. Materials and Methods

2.1 Magnet Selection Criteria

The selection of magnets for MSPRs was based on the following criteria:

• Magnetic Strength: Sufficient to generate effective stirring within the reactor volume.

• Corrosion Resistance: Ability to withstand chemical attack from the reaction medium.

• Temperature Stability: Maintenance of magnetic properties over the operating temperature range.

• Cost-Effectiveness: Balancing performance with economic considerations.

2.2 Magnet Types Evaluated

Several types of magnets were considered, including neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), alnico, and ferrite magnets. Each type was evaluated based on its magnetic properties, material compatibility, and cost.

2.3 Experimental Setup

A prototype MSPR was constructed with a transparent reactor vessel to allow for observation and light penetration. Magnets of varying sizes and types were placed outside the reactor wall, connected to a magnetic stirrer plate. The stirring performance was assessed by monitoring the mixing patterns and fluid velocity within the reactor.

3. Results and Discussion

3.1 Magnetic Properties and Stirring Performance

NdFeB magnets exhibited the highest magnetic strength, resulting in the most effective stirring within the reactor. SmCo magnets performed similarly but were more expensive. Ferrite magnets, while cost-effective, had lower magnetic strength and thus limited stirring efficiency. Alnico magnets were not considered due to their lower magnetic properties and susceptibility to corrosion.

3.2 Material Compatibility

All magnet types evaluated showed good resistance to corrosion in typical photocatalytic reaction media, including aqueous solutions containing photocatalysts such as titanium dioxide. However, long-term exposure to aggressive chemicals or high temperatures may require further evaluation of material compatibility.

3.3 Cost Considerations

NdFeB magnets offered the best balance between performance and cost, making them the preferred choice for MSPRs. The higher initial cost of SmCo magnets was not justified by their marginal increase in stirring efficiency.

4. Conclusion

This study provides a comprehensive analysis of magnet selection for MSPRs, considering magnetic properties, stirring performance, material compatibility, and cost-effectiveness. NdFeB magnets were identified as the optimal choice, offering high stirring efficiency, good material compatibility, and cost-effectiveness. 

Keywords: Magnetic Stirring Photocatalytic Reactor, Magnets Selection, Stirring Performance, Material Compatibility, Cost-Effectiveness.