Sains Malaysiana 55(9)(2026): 1568-1578

http://doi.org/10.17576/jsm-2026-5509-13

 

Enhanced Visible-Light-Induced Photocatalytic Activity for Cr(VI) Reduction over Magnetic Fe₃O₄-CdS Nanocomposites

(Aktiviti Fotopemangkinan Teraruh Cahaya Nampak yang Dipertingkatkan untuk Pengurangan Cr(VI) berbanding Nanokomposit Fe₃O₄-CdS Magnetik)

 

CANCAN XU^1,3, YAWEI XIE² & RUI LIU^1,*

 

¹Department of Environment, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, Jiaxing, 314006, China

²College of Civil Engineering, Zhejiang University of Technology, Hangzhou, 310023, China

³School of Modern Agriculture, Jiaxing Vocational & Technical College, Jiaxing, 314036, China

 

Received: 7 November 2025/Accepted: 7 September 2026

 

*Corresponding author; email: liuruitsinghuazj@gmail.com

 

Abstract

Photocatalytic reduction of toxic hexavalent chromium (Cr(VI)) to less harmful Cr(III) using semiconductor nanomaterials under ambient conditions is a promising solar-driven remediation approach. However, conventional photocatalysts (such as CdS) often suffer from low efficiency and poor recyclability. A multifunctional visible-light photocatalyst, Fe₃O₄-CdS nanocomposite, with magnetic separation capability and improved Cr(VI) reduction activity, was successfully fabricated via a hydrothermal method in this study. Structural characterization confirmed the formation of spherical nanoparticles (the average particle size was approximately 66.5 nm) with good magnetic responsiveness. Although nanoscale Fe₃O₄ (nFe₃O₄) itself showed no photocatalytic activity under visible light, its composite with CdS significantly improved the transfer of photogenerated electrons in CdS. This enhanced charge extraction, thereby suppressing electron-hole recombination and ultimately leading to improved Cr(VI) reduction efficiency. The incorporation of Fe₃O₄ effectively enhances the visible-light response capability of the Fe₃O₄-CdS nanocomposite. The optimal nFe₃O₄ content was 20 wt%, with the composite exhibiting a reaction rate three times higher than that of pure CdS. Photocatalytic performance was positively influenced by lower Cr(VI) concentration, higher catalyst dosage, and acidic pH. Notably, the catalyst remained effective over a broad pH range (3.2 - 9.6). After six reuse cycles, the Cr(VI) removal efficiency decreased slightly from 99.3% to 90.5%, indicating excellent stability and reusability. These findings suggest that Fe₃O₄-CdS nanocomposites are promising photocatalyst for efficient and sustainable Cr(VI) remediation under visible light.

Keywords: Cr(VI); enhanced photocatalysis; Fe₃O₄-CdS nanocomposites; magnetic recovery; reduction

 

Abstrak

Penurunan fotokatalitik kromium heksavalen toksik (Cr(VI)) kepada Cr(III) yang kurang berbahaya menggunakan bahan nano semikonduktor di bawah keadaan ambien merupakan pendekatan pemulihan berasaskan tenaga suria yang berpotensi. Namun begitu, fotokatalis konvensional (seperti CdS) sering menghadapi masalah kecekapan rendah dan kebolehgunaan semula yang lemah. Dalam kajian ini, satu fotopemangkin cahaya tampak pelbagai fungsi, iaitu nanokomposit Fe₃O₄-CdS dengan keupayaan pemisahan magnet dan aktiviti penurunan Cr(VI) yang dipertingkatkan, telah berjaya dihasilkan melalui kaedah hidroterma. Pencirian struktur mengesahkan pembentukan nanozarah berbentuk sfera (saiz purata zarah kira-kira 66.5 nm) dengan tindak balas magnet yang baik. Walaupun nanosfera Fe₃O₄ (nFe₃O₄) sendiri tidak menunjukkan sebarang aktiviti fotokatalitik di bawah cahaya tampak, gabungannya dengan CdS secara signifikan meningkatkan pemindahan elektron terjana cahaya dalam CdS. Ini mempertingkatkan pengekstrakan cas, seterusnya menekan rekombinasi elektron-lubang dan akhirnya meningkatkan kecekapan penurunan Cr(VI). Penggabungan Fe₃O₄ dengan berkesan meningkatkan keupayaan respons cahaya tampak bagi nanokomposit Fe₃O₄-CdS. Kandungan optimum nFe₃O₄ ialah 20 wt% dengan komposit menunjukkan kadar tindak balas tiga kali ganda lebih tinggi berbanding CdS tulen. Prestasi fotokatalitik turut dipengaruhi secara positif oleh kepekatan Cr(VI) yang lebih rendah, dos pemangkin yang lebih tinggi, dan pH berasid. Menariknya, pemangkin kekal berkesan dalam julat pH yang luas (3.2–9.6). Selepas enam kitaran penggunaan semula, kecekapan penyingkiran Cr(VI) hanya menurun sedikit daripada 99.3% kepada 90.5%, menunjukkan kestabilan dan kebolehgunaan semula yang sangat baik. Keputusan ini menunjukkan bahawa nanokomposit Fe₃O₄-CdS merupakan fotokatalis yang berpotensi tinggi untuk pemulihan Cr(VI) yang cekap dan lestari di bawah cahaya tampak.

Kata kunci: Cr(VI); fotokatalisis dipertingkat; nanokomposit Fe₃O₄-CdS; pemulihan magnet; penurunan

 

 

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