7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Upcycling of Ni(II) from electroplating wastewater to plasma NH3 synthesis
catalysis
Hongli Wang, Dezheng Yang
Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Dalian University ofTechnology), Ministry of Education, Dalian 116024, Chinae-mail (speaker): wanghongli110@mail.dlut.edu.cn

Treating heavy metal Ni(II) ions from the electroplating
industry is mandated word-wide. After multi-stage
treatment processes, the Ni(II) concentration inwastewater can reach between a few ppm to several tensof ppm, which still does not meet the national permitted
discharge standards. Adsorption is considered to be aneffective method for treating low concentration nickel
due to its low cost, eco-friendliness, and high processing
efficiency. MCM-41 zeolites have been used for theremoval heavy metal ions in wastewater due to theuniform pore size distribution, excellent transports
properties, and high flexibility for surface modification.
Traditional chemical impregnation can effectively
improve the chemical composition of MCM-41 andadsorption efficiency, it also causes pore blockage anddecreased specific. Nanosecond pulse discharge
modification technology can increase the specific surface
area through plasma cleaning and pore-making effects,
and implant oxygen-containing functional groups under
the action of strong oxidizing radicals. Therefore, thecombination of chemical impregnation with plasma
modification can improve the physical structure andchemical composition, and enhance the adsorption
capacity for heavy metal ions.
Rather than regarding Ni(II) as a disposable waste,
the chemicals industries could instead consider it a hugeresource. Research shows that Ni(II) based catalysts havesignificant effects in plasma catalyzed NH3 synthesis.
Therefore, in this study, we prepared a porous zeolites

rich in functional groups as an excellent adsorbent for
the removal of Ni(II) ions using nanosecond pulse
discharge-amino co-functionalization method. The
adsorbed nickel catalyst was calcined to prepare aNi(II)-based catalyst for plasma-catalyzed NH3 synthesis.
It was found that the nanosecond pulse discharge-amino
co-functionalization enables the zeolites to achieve 98%of Ni(II) ions removal efficiency. The residual Ni(II) ionsconcentration in solution was well below national
permitted discharge standard for Ni(II). The excellent
adsorption capacity is mainly due to the high porosity,
the increase in specific surface area, and the existence ofhigh concentration -NH2 and -COOH. The highest NH3synthesis rate of 1200 µmol/h was achieved using
Ni/MCM-41, which was four times higher than thatobtained using plasma only. This strategy of upcycling
metal waste into functional, catalytic materials offers amultipronged approach for clean and renewable energytechnologies.

References[1] Shenghua Wang et al, Nat. Commun. 5305 13 (2022).
[2] Huicai Wang et al, Chem. Eng. J. 383, 123107(2020).
[3] Yaolin Wang et al, J. Am. Chem. Soc. 144,
12020−12031 (2022).

Figure 1. Residual Ni(II) concentration in solution as a function of adsorption time (left) and Reported NH3 synthesis
rate vs energy yield in the plasma-catalytic NH3 synthesis using DBD.