The adsorption of reactive blue 4 (RB4) and acid red 183 (AR183) on a multiwall carbon nanotube (MWCNT) was investigated in single and binary dye systems. The MWCNT presented a higher adsorption of RB4 than AR183 in single and binary dye systems, due to stronger interactions. In single dye solutions, adsorption capacities of the MWCNT for RB4 and AR183 at 25 °C are (69 and 45) mg·g–1, respectively. The higher temperature resulted in lower adsorption of the dyes on the MWCNT. In binary dye solutions, RB4 and AR183 showed competitive adsorption, resulting in RB4 adsorption but desorption of AR183 on the MWCNT. RB4 adsorption capacity in binary dye systems was also reduced to 56 mg·g–1 at 25 °C. The interaction of the dyes with MWCNT was found to be dominated by electrostatic attraction.

h i g h l i g h t s" Adsorption of methylene blue and acid red 183 on a MWCNT in single and binary dye systems was investigated. " MWCNT shows higher adsorption capacity to methylene blue in both systems. " A synergistic effect for basic and acid dyes occurs in a binary dye system. t r a c tA multiwalled carbon nanotube (MWCNT) was used as an adsorbent for removal of a cationic dye (methylene blue, MB) and acid dye (acid red 183, AR183) from aqueous solution in single and binary dye systems. Characterization of the MWCNT and MWCNT-dye systems were performed using several techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential thermal analysis (TG-DTA), zeta potential and elemental analysis. Adsorption tests showed that the MWCNT presented higher adsorption of MB than AR183 in single and binary dye systems, revealing that p-p stacking is the main driving force responsible for the dye-MWCNT interaction. In single dye systems, the MWCNT presented the maximum adsorption capacities of MB and AR183 at 59.7 and 45.2 mg/g, respectively. In a binary dye system, a synergistic effect due to electronic attraction between MB and AR183 was found at low AR183 concentration (10 mg/L), which promotes the adsorption of both dyes on the MWCNT. However, MB adsorption could be reduced at higher AR183 concentration (>20 mg/L) due to a strong electrostatic attraction between MWCNT-AR183.

In recent years, multi-axis robots are indispensable in automated factories due to the rapid development of Industry 4.0. Many related processes were required to have the increasing demand for accuracy, reproducibility, and abnormal detection. The monitoring function and immediate feedback for correction is more and more important. This present study integrated a highly sensitive lithium niobate (LiNbO3) vibration sensor as a sensor node (SN) and architecture of wireless mesh network (WMN) to develop a monitoring system (MS) for the robotic arm. The advantages of the thin-film LiNbO3 piezoelectric sensor were low-cost, high-sensitivity and good electrical compatibility. The experimental results obtained from the vibration platform show that the sensitivity achieved 50 mV/g and the reaction time within 1 ms. The results of on-site testing indicated that the SN could be configured on the relevant equipment quickly and detect the abnormal vibration in specific equipment effectively. Each SN could be used more than 10 h at the 80 Hz transmission rate under WMN architecture and the loss rate of transmission was less than 0.01% within 20 m.