A simple, cheap and effective functional paper has been fabricated to absorb and detect Cu2+ with good
sensitivity and selectivity. Using commercial cellulose filter papers as substrate, Magneli phase structure of Ti6O11 was coated at the surface to serve as intermediate linker to modify N-[3-(Trimethoxysilyl)
propyl] ethylenediamine for Cu2+ binding. Under optimized conditions, i.e. at 50 ◦C with electromagnetic stirring, the functional paper can adsorb Cu2+ with high performance and give clear color response
using cupron as chromogenic agent. The concentration-dependent colorimetric response (B value)
matches well with the exponential linear curve under dynamic adsorption conditions, where the linear range was from 33.6 nM to 39.8 M and the detection limit was measured to be about 33.6 nM.
Measurement of a group of possible interfering ions and spiked real water samples demonstrated the
good selectivity of the proposed paper. Furthermore, the performance can be further improved using
microwave irradiation, where a lower detection limit of 16.8 nM was achieved within a wider linear
range from 16.2 nM to 0.98 mM. The reaction time can be shortened to 20 min to reach final equilibrium and the saturated adsorption amount of Cu2+ for a single piece of paper (diameter = 1.0 cm) was as
high as 4.5169 g/cm2. The proposed functional papers would offer an effective alternative for potential
adsorption and determination of copper ions in real applications.