The presence of dyes in water is the most popular problem recently, so the current study was directed towards the synthesis of an effective material consisting of NiO and MWCNTs. The NiO/F-MWCNTs nanocomposite was synthesized using a simple hydrothermal method after functionalization of MWCNTs using sulfuric acid and nitric acid and utilized as an efficient surface to adsorption of malachite green dye from polluted water. The nanocomposite sample was characterized using several techniques are X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), High- resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) surface area analysis, Barrett-Joyner-Halenda (BJH) analysis and Energy dispersive X-ray (EDX). The analytical results showed that the prepared nanocomposite is of good crystalline nature with a particle size of 25.43 nm. A significant specific surface area was 412.08 m2/ g which indicates the effective impact of the nanocomposite in the adsorption of malachite green (MG) dye. On the other hand, the effect of adsorbent dose, temperature, acidic function and contact time on the adsorption efficiency of dye was studied. The kinetics of dye adsorption were also investigated employing two kinetic models, pseudo-first-order model and pseudo-second-order model. Finally, the thermodynamic functions were determined to identify the type of the reaction and the spontaneity of the process.

Perennial need for bactericides requires cost-effective nanomaterials with strong antibacterial activities even in the absence of external irradiation. Hence, in this work, we have synthesized f-CFT (fluorinated TiO2- doped, glycine-functionalized MWCNTs) and have studied its antibacterial activities. Both gram-negative and gram-positive bacteria were analyzed in the absence of photo-activation. Zone of inhibition of 15 mm for S. aureus, and 11 mm for P. aeruginosa was observed for f-CFT owing to the synergistic bactericidal properties of functionalized MWCNTs, fluorine and nano-TiO2. Anatase phase TiO2 with average crystallite size as 35 nm was observed in XRD. Scanning electron microscopic images showed uniform mixed cubic structures. Hydroxyl groups observed in FT-IR along with the glycine MWCNTs interface aid the inhibition of bacterial growth even in the absence of photo activation. A desired higher gram-positive bacterial inhibition opens new gates for better antibacterial agents.

Carboxylated multi-wall carbon nanotubes (MWCNTs-COOH) was functionalized with 3-amino-5-phenylpyrazole (MWCNTs- f) and characterized by FTIR, EDX, SEM, XRD and TGA. The MWCNTs-COOH and MWCNTs-f were used for the adsorption of Cd(II), Hg(II), and As(III) ions from aqueous solutions. Additionally, to study the influence of pH, adsorbent dose, and initial ions concentration on the adsorption process, the central composite design (CCD) was applied. The quadratic model was used for analysis of variance and indicated that adsorption of metal ions strongly depends on pH. Timedependent adsorption can be described by the pseudo-second-order kinetic model, and adsorption process was modeled by Langmuir isotherm for the adsorbents. Thermodynamic analysis showed that the adsorption of Cd(II), Hg(II) and As(III) ions were spontaneous and endothermic. Moreover, the competitive adsorption capacities of the heavy metal ions were slightly lower than noncompetitive ones. The same affinity order was observed under noncompetitive and competitive adsorption: As(III) > Cd(II) > Hg(II) in the case of MWCNTs-f. Desorption study revealed the favorable regeneration ability of adsorbents powders, even after three adsorption–desorption cycles.