Facile synthesis of mesoporous nano Ni/NiO and its synergistic role as super adsorbent and photocatalyst under sunlight irradiation.

Tailoring a material that has a synergistic role as an adsorbent and a photocatalyst for environmental application is an attractive field for research. This article presents a study of facile synthesis of NiO and Ni/NiO with a synergistic role as super adsorbents in the lake of light and photocatalysts under light irradiation. Nano flower-like mesoporous NiO and Ni/NiO were synthesized by the co-precipitation method. XRD, SEM, EDAX, XPS, BET, and DR/UV-Vis spectroscopy techniques were employed for samples' analysis. The point of zero surface charge of prepared samples was detected by the batch equilibrium method. The adsorption efficiency was investigated in the absence of light using aniline blue as a pollutant model dye. The synergistic effect as an adsorbent and a photocatalyst was investigated under UV and sunlight irradiation. Different parameters affecting the adsorption in the dark have been optimized. The results showed that in the absence of light, the prepared samples are super adsorbents with a maximum adsorption capacity ranging from 210 to 230 mg g-1 and a removal % ranging from 95 to 100% within 2 h. Under UV or sunlight irradiation, the adsorbent/photocatalyst attained a dye removal % of 99.8% within 30 min. The adsorption data matched the pseudo-second-order model, and the equilibrium adsorption data showed compatibility with Langmuir model. The findings of experiments revealed that the adsorption is spontaneous, exothermic, and results in less entropy. Under sunlight irradiation, the dye removal efficiency increased by 19% in the case of Ni/NiO hybrid; it showed a removal efficiency of 99.5% within 30 min under sunlight irradiation versus 80% after 120 min in the dark.

Cost-effective adsorbent from arabinogalactan and pectin of cactus pear peels: Kinetics and thermodynamics studies.

Cactus pear peel as agricultural waste containing arabinogalactan and pectin was thermally treated at 300 °C for 4 h and the resultant carbonized material was applied as adsorbent for the removal of methylene blue dye as a model cationic dye. The prepared adsorbent was characterized by means FTIR for structural characterization, N2 physisoprtion measurements for texture properties, SEM and EDAX for morphological and elemental analysis. The characterization results clearly show that the prepared material is porous with several -OH and CO terminals. The point of zero charge was found to be 7 as detected by batch equilibrium method. The adsorption process was optimized in terms of pH values, contact time, initial dye concentration and temperature. The kinetic study indicated that the pseudo-second-order model can perfectly describe the investigated adsorption process; moreover, the equilibrium results were best fitted by Freundlich model. Furthermore, at pH 8.0, the adsorption capacity was achieved to the maximum value of methylene blue as 102 mg/g. Thermodynamic investigation showed that the adsorption process is spontaneous, endothermic in nature with higher entropy, while the activation energy calculations indicated a physisorption process. The obtained results showed the high potential of the bio-based adsorbent for removal of methylene blue from wastewater.