Hydrothermal tuning of the morphology and particle size of hydrozincite nanoparticles using different counterions to produce nanosized ZnO as an efficient adsorbent for textile dye removal

Abstract

The current study aimed to investigate the effect of counterions on hydrothermally synthesized hydrozincite (zinc hydroxide carbonate), which was thermally converted to generate ZnO nanostructures, which are an efficient nanoadsorbent for the removal of Reactive Black 5 (RB5) dye from wastewater. Hydrozincite nanospheres and flower-like structures were hydrothermally prepared using various zinc salts (sulfate, acetate, and nitrate) and ammonium carbonate in a molar ratio of 1 : 3, respectively, at 120 C for 3 h. The morphology and crystallite size of the hydrozincite precursor were effectively controlled via the parameters of the hydrothermal reaction. Interestingly, sulfate was the optimum counterion, as zinc sulfate salt produced pure hydrozincite nanospheres with the smallest crystallite size ($13.57 nm), which were consequently thermally decomposed at 400 C for 1 h to produce pure nanosized ZnO ($10 nm). The compositions of the as-synthesized products were determined by means of FT-IR, FE-SEM, HR-TEM, XRD, zeta potential, BET, and thermal analyses. An adsorption study showed a much higher adsorption capacity (80.9 mg g À1 ) of the as-prepared ZnO nanoparticles toward RB5 dye. The adsorption of RB5 dye followed pseudo-second-order kinetics. In addition, the equilibrium adsorption of RB5 dye was best described by a Langmuir isotherm model and the calculated thermodynamic parameters, DG 0 (from À4.027 to À7.533 kJ mol À1 ), DH 0 (30.798 kJ mol À1 ), and E a (29.105 kJ mol À1 ), indicate the spontaneous, endothermic, and physisorptive nature of the adsorption process.

A facile Pechini sol–gel synthesis of TiO2/Zn2TiO2/ZnO/C nanocomposite: an efficient catalyst for the photocatalytic degradation of Orange G textile dye

“…Thus, many researchers have devoted much of their research work to the treatment of wastewater of the textile industries before the disposal process. [7][8][9] To date, different chemical, biological, and physical procedures have been proposed for the removal of pollutants from wastewater including chemical oxidation, precipitation, reverse osmosis, ltration, membrane process, solvent extraction, adsorption, electrochemical and ultrasonic technique, biological treatment, and coagulation. 6,[10][11][12][13][14][15] On the other hand, the photocatalytic degradation process has proven its efficiency for the removal of various textile dyes.…”

Tunable auto-combustion preparation of TiO2nanostructures as efficient adsorbents for the removal of an anionic textile dye

“…This behavior is similar to that reported for the adsorption of RB5 dye on ZnO nanoparticles. 4 In order to understand the adsorption mechanism, the experimental kinetic data of RR195 dye adsorption on TiO 2 adsorbent were examined using pseudo-rst-order 55 and pseudosecond-order 56 models expressed by eqn (5) and (6), respectively. logðq e À q t Þ ¼ log q e À k 1 2:303 t (5)…”

“…We also estimated DG 0 value using eqn (14) by knowing DH 0 and DS 0 values. The calculated thermodynamic parameters are tabulated in Table (4). The tabulated thermodynamic values in Table (4) show that the partition coefficient constant is more appropriate than the distribution coefficient for calculating the thermodynamic constants owing to the higher correlation coefficient (r 2 ¼ 0.9204) of van't Hoff equation in the case of K c ¼ K p on comparing to K c derived from K d (r 2 ¼ 0.786).…”

“…In addition, these dyes are toxic and carcinogenic owing to the presence of azo groups (-N]N-) in their molecular structures. 4 Besides, these dyes cause serious problems to human health such as irritation, respiratory issues chemical burns, ulcers, etc. 5,6 Hence, the removal of the organic dyes (especially the textile dyes) from wastewaters is one of the critical necessities for human and environmental safety.…”

“…The scientists found their way in nano-sized materials which have been regarded as an important type of adsorbent materials for the removal of heavy metals and organic pollutants from wastewater. 2,4,[20][21][22][23] However, reports on the removal of Reactive Red 195 (RR195) dye from wastewater are still limited. 2,20 Besides, searching for the most suitable nano-adsorbent is still a challenge.…”