In this work, titanomagnetite was used as a heterogeneous Fenton catalyst for the degradation of methylene blue (MB). The degradation of MB on synthetic titanomagnetite at neutral pH values was studied in comparison with the adsorption of MB on titanomagnetite using UV−vis, FTIR, and the analyses of element C on titanomagnetite and DOC in reaction solution. Meanwhile, important factors affecting catalytic activity were investigated, that is, titanomagnetite load, H2O2 concentration, and reaction temperature. Titanomagnetite decomposed H2O2 yielding highly reactive hydroxyl radicals, and MB adsorbed on titanomagnetite was degraded. With the increases of titanomagnetite load, H2O2 concentration, and reaction temperature, the degradation of MB was promoted. Moreover, titanomagnetite was proved to be durable with a stable MB removal efficiency after five consecutive cycles.

This study demonstrates the possibility of a reversible naked-eye detection method for submicromolar levels of cadmium(II) using the Langmuir-Blodgett (L-B) technique. Molecular assemblies of 4-n-dodecyl-6-(2-thiazolylazo)resorcinol are transferred on precleaned microscopic glass slides, to act as a sensing probe. Isotherm (pi-A) measurements were performed to ensure the films' structural rigidity and homogeneity during sensor fabrication. The sensor surface morphology was characterized using atomic force microscopy and scanning electron microscopy. The probe membrane exhibits visual color transition, forming a series of reddish-orange to pinkish-purple complexes with cadmium, over a wide concentration range (0.04-44.5 microM). Cadmium response kinetics and the changes in the sensors' intrinsic optical properties were monitored using absorption spectroscopy and further confirmed using X-ray photoelectron spectroscopy. A hybrid L-B film composite of poly(vinyl stearate) and poly(vinyl-N-octadecylcarbamate) were investigated for enhancing sensor performance. The sensor was tested for its practical approach to prove its cadmium selectivity and sensitivity amid common matrix constituents using synthetic mixtures and real water samples. Using the sensor strips, the respective lower limits of cadmium detection and quantification are 0.039 and 0.050 microM, as estimated from a normalized linear calibration plot.