SiO₂and Diphenylcarbazide Doped Polymethylmethacrylate Electrospun Fibrous Film For Cadmium Colorimetric Detection

Heavy metal ions have deleterious effects on the environment and living organisms,particularly at high levels of concentration. Cadmium ions (Cd2+), one of the most toxicheavy metal ions and a severe environmental pollutant that is not biodegradable, has seriousdeleterious effects on human health. Humans are exposed to Cd2+through the ingestion ofcontaminated food or water and inhalation of cigarette smoke. Cd2+causes a number oflesions in many organs and tissues such as the kidney, liver, gastrointestinal tract, brain, andbone. In addition, chronic exposure to Cd2+has been implicated as a cause of cancers of thelung, prostate, pancreas, and kidney. Therefore, the rapid and sensitive detection of Cd2+inwater or food resources plays an important role in environmental protection and food safety.The instant and on-site detection of trace aqueous cadmium ions still remains achallenge for environmental monitoring and protection. This work demonstrates a newanalytical method and its utility for visual detection of aqueous Cd2+on the basis of a novelsolid-state, fiberous-based optical sensor. Diphenylcarbazide (DPC, a chromophore) andSiO2nanopartical doped polymethylmethacrylate (PMMA)(denoted as SiO2@DPC@PMMA) microporous fiberous film has been achieved via simple electrospinning, and usedfor highly sensitive and selective naked-eye detection of Cd2+in aqueous solution. SDPfiberous film, compared with DPC@PMMA fiberous film, its color was significantlyenhanced with the presence of extremely low concentration cadmium ions. Because SiO2-doped treatment of nanofiber further improves its S/M ratio by generating a highly beadsurface morphology throughout the nanofiber backbone. The detection limit was found to be1×10-8M without any assistance of equipment. Upon exposure to a series of metal ions,only Cd2+could induce a yellowish-to-red color change, fibrous film turned brown in thepresence of Cu2+. To improve the selectivity of the fibrous film toward Cd2+, we appliedthiourea as a masking agent to mask the interference of Cu2+, which clearly exhibited thatDPC immobilized SDP fiberous film could act as highly selective strips to detect Cd2+with little interference from other metal ions. At last, this study provides basic information forthe visual detection of Cd2+in sensing applications, and provides a new idea for test stripsassay for Cd2+.