Vol.:(0123456789) 1 3 Journal of the Iranian Chemical Society https://doi.org/10.1007/s13738-019-01846-5 ORIGINAL PAPER Highly active copper in dye discoloration via a heterogeneous Fenton‑like process Meriem Hamidani 1  · Souad Djerad 1  · Lakhdar Tifouti 1  · Mohamed Boulkra 2 Received: 21 September 2019 / Accepted: 27 December 2019 © Iranian Chemical Society 2020 Abstract This study presents the discoloration of methylene blue by heterogenous Fenton-like process using copper. Copper was pre- pared with sodium ascorbate, an eco-friendly reagent under atmospheric conditions and characterized using X-ray difraction and scanning electron microscope analysis. Sub-micron-sized particles were formed and mainly composed of metallic copper Cu with the minor presence of Cu 2 O. The obtained product (labeled as Cu R ) was compared to a commercial zero-valent cop- per (labeled as Cu F ) in the discoloration process of methylene blue. Diferent parameters such as copper loading, temperature and initial dye concentration were studied. Under the same conditions, Cu R and Cu F registered 95.04% and 20.46%, respec- tively, after 10 min of reaction. The discoloration process was due to the in situ production of H 2 O 2 which was evidenced by permanganate method. It was found the formation of 0.18 mM and 75 µM of H 2 O 2 after 2 min of reaction with Cu R and Cu F , respectively. The reaction rate with Cu R was 5 times faster than that with Cu F and both followed a pseudo-frst-order reaction kinetic. The high activity observed with Cu R was found to be due to the presence of Cu 2 O. Keywords Ascorbate · Copper · Green process · Dye discoloration · Heterogeneous Fenton-like · In situ H 2 O 2 production Introduction Environmental pollution is one of the most critical and urgent problems of the world. Industries are the major pol- luters generating solid wastes and liquid efuents containing metals, dyes and other products that need to be treated [1–4]. Dyes are used to color textiles, leather, foods, medicines, cosmetics and papers. Approximately 10–15% dyes are released into the environment making the efuents highly colored and aesthetically unpleasant, but it is in the textile industry that the largest quantities of colored efuents are discharged from dyeing processes [5]. Dye molecules are difcult to remove with conventional water treatments and can be transported easily through sewers and rivers because of their high water solubility [6]. In the last decades, the decrease in rainfall is observed while water demand is in a constant increase. This situation makes the world’s popula- tion to face severe water crises. This problem constitutes a major challenge for researchers to develop cost-efective technologies for wastewater treatment [7]. Advanced oxida- tion processes (AOPs) are alternatives to the other treatments of wastewaters. They involve the generation of hydroxyl rad- icals which are a kind of green and non-selective oxidants that aggressively attack all organic compounds [8–10]. One of the most frequently used AOPs is the Fenton process. Fenton’s reagent is able to destroy diferent kind of organic contaminants such as phenols, nitrobenzene and herbicides in water [11]. Traditional Fenton (H 2 O 2 /Fe 2+ ) involves the reaction between hydrogen peroxide (oxidant) and ferrous ion (catalyst) generating hydroxyl radicals in homogene- ous system. This system has many advantages such as its high performance and its non-toxicity [12–15]. However, it involves excessive consumption of hydrogen peroxide, which can be costly and which handling can be unsafe. One of the means to overcome this problem is the in situ produc- tion of hydrogen peroxide. In situ production of H 2 O 2 means its production at the time of treatment. From the literature, diferent methods can be employed to produce H 2 O 2 in situ such as metals catalyzed reaction, ozonation, photocataly- sis, electrochemical or microbial fuel cells [16]. In metal/O 2 * Souad Djerad s_djerad@hotmail.com 1 Laboratory of Environmental Engineering, Department of Process Engineering, Badji Mokhtar- Annaba University, P.O. Box 12, 23000 Annaba, Algeria 2 Research Center in Industrial Technology RCIT, P.O. Box 64, 16014 Cheraga, Algiers, Algeria