A Magnetic Photocatalytic Composite Derived from Waste Rice Noodle and Red Mud
This study is the first to convert two waste materials, waste rice noodles (WRN) and red mud (RM), into a low-cost, high-value magnetic photocatalytic composite. WRN was processed via a hydrothermal method to produce a solution containing carbon quantum dots (CQDs). Simultaneously, RM was dissolved...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-12-01
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| Series: | Nanomaterials |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-4991/15/1/51 |
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| Summary: | This study is the first to convert two waste materials, waste rice noodles (WRN) and red mud (RM), into a low-cost, high-value magnetic photocatalytic composite. WRN was processed via a hydrothermal method to produce a solution containing carbon quantum dots (CQDs). Simultaneously, RM was dissolved in acid to form a Fe<sup>3+</sup> ion-rich solution, which was subsequently mixed with the CQDs solution and underwent hydrothermal treatment. During this process, the Fe<sup>3+</sup> ions in RM were transformed into the maghemite (γ-Fe<sub>2</sub>O<sub>3</sub>) phase, while CQDs were incorporated onto the γ-Fe<sub>2</sub>O<sub>3</sub> surface, resulting in the CQDs/γ-Fe<sub>2</sub>O<sub>3</sub> magnetic photocatalytic composite. Experimental results demonstrated that the WRN-derived CQDs not only facilitated the formation of the magnetic γ-Fe<sub>2</sub>O<sub>3</sub> phase but also promoted a synergistic interaction between CQDs and γ-Fe<sub>2</sub>O<sub>3</sub>, enhancing electron-hole pair separation and boosting the production of reactive radicals such as O<sub>2</sub><sup>·−</sup> and ·OH. Under optimized conditions (pH = 8, carbon loading: 10 wt%), the CQDs/γ-Fe<sub>2</sub>O<sub>3</sub> composite exhibited good photocatalytic performance against methylene blue, achieving a 97.6% degradation rate within 480 min and a degradation rate constant of 5.99 × 10<sup>−3</sup> min<sup>−1</sup>, significantly outperforming RM and commercial γ-Fe<sub>2</sub>O<sub>3</sub> powder. Beyond methylene blue, this composite also effectively degraded common organic dyes, including malachite green, methyl violet, basic fuchsin, and rhodamine B, with particularly high efficiency against malachite green, reaching a degradation rate constant of 5.465 × 10<sup>−2</sup> min<sup>−1</sup>. Additionally, due to its soft magnetic properties (saturation magnetization intensity: 16.7 emu/g, residual magnetization intensity: 2.2 emu/g), the material could be conveniently recovered and reused after photocatalytic cycles. Even after 10 cycles, it retained over 98% recovery and 96% photocatalytic degradation efficiency, underscoring its potential for cost-effective, large-scale photocatalytic water purification. |
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| ISSN: | 2079-4991 |