Recycling application of heating pad waste as catalyst and adsorbent for organic and inorganic arsenic removal: Performance and mechanism

Abstract

Heating pad waste (HPW), a magnetically recyclable material collected from disposable heating pads, is produced in amounts of millions of tons every year globally. HPW is mainly composed of Fe, C and O, directly disposal caused a waste of resource. In this paper, HPW was used to activate peroxymonosulfate (PMS) for roxarsone (ROX) degradation and as a functional adsorbent for the simultaneous adsorption of the released inorganic arsenic. After 2 h, 20 μM (1.5 mg-As/L) ROX was completely degraded, and the released inorganic arsenic was effectively adsorbed by HPW. Mechanism study proved •OH, SO4•−, and 1O2 were all existed in the HPW/PMS system, and •OH was the dominant reactive species. And the possible degradation pathways of ROX were further proposed based on the identified intermediates. Furthermore, the result of TCLP test showed that the leaching As concentration of the used HPW (0.146 mg/L) is far below the current identification standards for hazardous wastes-identification for extraction toxicity value on As (GB 5085.3-2007, 5 mg/L). This study adopted the strategy of “treat waste by waste”, achieved the resource utilization of HPW, brought economic and environmental benefit to environment remediation.