Rapid removal of copper from wastewater by Fe-based amorphous alloy

Highlights

• Fe-based amorphous alloys have excellent degradation properties for the removal of copper ions from wastewater.

• The higher removal efficiency and lower reaction activation energy are because of the unique surface mobility.

• The copper ion can be reduced to less than 0.5 or 1 ppm at different initial concentrations.

Abstract

Fe-based amorphous alloys have been proved to exhibit excellent degradation properties for the removal of copper ions from simulated wastewater. Compared with crystalline iron, amorphous alloy has higher removal efficiency, lower reaction activation energy and high corrosion current density owing to its unique surface mobility. The copper ion can be reduced to less than 0.5 or 1 ppm at different initial concentrations. Even at a lower concentration of copper ions, it also exhibits better performance. In comparison, the concentration of the copper ion would be higher than the prescribed discharge standard if the wastewater was treated by crystalline iron. This work provides a potential application of Fe - based amorphous in the removal of heavy metal ions from wastewater.

Introduction

Our world is now facing many unprecedented environmental threats, one of which is water pollution [[1], [2], [3]]. Metals such as lead, cadmium, copper, arsenic, nickel, chromium, zinc and mercury are recognized as the hazardous heavy metals, resulting in damage to blood composition, lungs, kidneys, liver and other vital organs [2,4]. Even at low concentrations, the wastewaters containing these heavy metals still exhibit strong toxicity to human body [5,6]. In the past centuries, the world-wide rapid industrialization has greatly aggravated the release of these toxic heavy metals to water streams. At present, the discharge of contaminative wastewater is a common concern environmental problem of humankind. As the main sources of heavy metal ion contamination, electroplating, metal processing, printed circuit board (PCB) manufacturing, mining, textile and battery manufacturing industry are making this problem more and more serious [7,8].

Among the heavy metals, copper ion (Cu²⁺) is a common hazardous pollutant in wastewater and is often released by metallurgical, plating, printing circuits, fertilizer and refining industries [9,10]. Though Cu²⁺ is known to be a necessary trace element [[11], [12], [13]],but it can accumulate in living organisms, causing several disorders and diseases [[14], [15], [16], [17]]. According to the regulations of world health organization (WHO), the guideline value for Cu²⁺ in drinking-water is 2.0 mg/L [13]. However, the concentration of the copper ion in the industrial effluent ranges from tens to even thousands mg/L in different industrial fields, which is tremendously far higher than the regulations. Furthermore, when the concentration of Cu ion becomes very low, it will be very costly to decrease the concentration by traditional methods including electrochemical operations, reverse osmosis, or chemical treatment processes [[18], [19], [20], [21], [22]].

Metallic glasses, alternatively known as amorphous alloys, including Fe- [[23], [24], [25], [26]],Mg- [27],Al- [28]and Co- [29]based amorphous alloys have been very interesting catalytic materials for degrading the water contaminants due to the intrinsic difference of their disordered atomic packing arrangement compared with the well-defined atomic ordering in crystalline materials [23,24,[30], [31], [32], [33]]. In recent experiments, it was discovered that the surface mobility is very different from the bulk in amorphous matters owing to the disordered structure [34], including glassy polymers [35], oxide glasses [36], organic glasses [37], amorphous alloys [38,39] et al. Evidences showed that the surface diffusion was dominated by the mono-atomic layer for the crystalline solid, however, as for the amorphous matters, the domination layer could be as thick as nanometer [40,41]. Specifically, the surface diffusion rate of amorphous alloy is millions of times higher than the bulk when subject at temperature below glass transition temperature. That is to say, there exists a “super active” layer with high mobility on the surface of amorphous alloys [38]. Inspired by such fast surface mobility of amorphous alloy, in this work we present the rapid removal of copper ions from wastewater could be achieved by the Fe-based amorphous alloy ribbons. Furthermore, by using such method, no secondary pollution is caused, the resultant of reaction is pure copper, which can be collected and reused. Therefore, it is proved to be an efficient and cost-saving method to prevent the copper ion pollution in wastewater, showing great significance in the sense of environmental protection.