Synthesis of zinc oxide derived from wastewater of glove manufacturing via adsorption-desorption-precipitation path

The demand for ZnO significantly increased over the past decades. Extraction and refinement of zinc ores results in the release of hazardous wastes to the environment. In particular, the tremendous demand for disposable nitrile gloves during the Covid-19 pandemic has spiked superior demand for ZnO used as a crosslinking agent in the manufacturing process and leads to the generation of zinc containing wastewater traditionally removed via chemical precipitation. This paper focuses on the application of adsorption for zinc removal which opens an opportunity to recycle zinc to synthesize secondary zinc oxide. This study evaluated the feasibility of zinc oxide synthesis via the adsorption-desorption-chemical precipitation pathway. Palm shell activated carbon (PSAC), a low-cost adsorbent, was used for the removal of zinc from the synthetic and industrial wastewaters. Subsequently, zinc desorption was carried out using 0.3 M HCl. Then ZnO was synthesized from the desorption solutions via chemical precipitation using potassium hydroxide. Average zinc conversion rate of 98 % was achieved in this study. The synthesized ZnO exhibited high surface area of 97.4 m²/g after calcination (400 °C, 3 hr), high purity and crystallinity. The results confirmed the feasibility of zinc ions recovery for recycling to produce secondary good quality zinc oxide.