Efficient performance of copper oxide nanoparticles synthesized with pomegranate leaf extract for neutral red dye adsorption

Abstract

The adsorption of dyes in water and wastewater using metallic nanoparticles stands out due to its high removal capacity and low environmental impact. The present study proposed the use of copper oxide nanoparticles (CuO_NP), synthesized with pomegranate leaves extract (Punica granatum) to remove the neutral red (NR) dye from the aqueous medium. The characterization confirmed the efficiency of the redox process and the formation of nanoparticles. The adsorption results were promising, wherein the maximum adsorption capacity was 283 mg/g (298 K), with 0.4 g/L of adsorbent concentration, equilibrium time at 120 min, and removal rate of 96%. The pseudo-second-order and Langmuir models had a better fit concerning the kinetic and isothermal data, respectively. Thermodynamic parameters revealed an exothermic, spontaneous, and reversible process. The mechanisms that described the adsorptive process were hydrogen bonds, π-interactions, and electrostatic attraction. CuO_NP showed good regeneration performance up to four reuse cycles (98-52 mg/g). In addition, not pronounced changes were verified in its adsorption capacity with dissociated ions (90-102 mg/g, in relation to the adsorption with no salts 104 mg/g). This secures the material versatility and cost-effectiveness, justifying its high potential for industrial application to remove NR from water and wastewater.

Efficient adsorptive removal of paracetamol and thiazolyl blue from polluted water onto biosynthesized copper oxide nanoparticles

“…The result indicated that the biosynthesized CuONPs were effectively regenerated and reused for the uptake of both pollutants from solution. This finding is consistent with the reports on the successful reuse of CuONPs for the adsorption of other pollutants from solution 48 , 49 , 54 , 55 .

Figure 11 The regeneration and reuse of the biosynthesized copper oxide nanoparticles for the uptake of thiazolyl blue and paracetamol (pH 8.0 for thiazolyl blue and pH 7.0 for paracetamol; concentration 100 mg/L; temperature 300 K, sonication time 120 min).

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“…Although the model qe value of the PFO model was closer the experimental value, the higher R 2 and lower SSE of the PSO model indicated a greater conformity of the adsorption to the PSO model. The best fit of the PSO model to the process corroborates the findings of most researchers on the uptake of various pollutants on CuONPs 27 , 29 , 32 , 54 , 55 , 58 , 65 – 67 . Therefore, based on its premise, the number of active sites occupied in the adsorbent is proportional how much adsorbate would be absorbed 54 , 55 , 68 .…”

“…The best fit of the PSO model to the process corroborates the findings of most researchers on the uptake of various pollutants on CuONPs 27 , 29 , 32 , 54 , 55 , 58 , 65 – 67 . Therefore, based on its premise, the number of active sites occupied in the adsorbent is proportional how much adsorbate would be absorbed 54 , 55 , 68 .…”

“…At the optimum adsorption observed at lower pH values of 2.0 to 8.0, it is apparent that electrostatic interaction did not have much influence on paracetamol adsorption on the biosynthesized CuONPs. Therefore, intermolecular mechanisms like hydrogen bonding and Van der Waals interactions which are unaffected by charged species in the solution probably govern the adsorption of paracetamol 55 .

Figure 7 The influence of pH on the uptake of thiazolyl blue and paracetamol on the biosynthesized copper oxide nanoparticles (Sonication time 120 min; temperature 300 K; concentration 100 mg/L).

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“…Hence, we selected a neutral pH of 7.0 for the adsorption of paracetamol. Some researchers also reported a negligible influence of pH on the www.nature.com/scientificreports/ adsorption of other safranin-O and neutral red pollutants on CuONPs 54,55 . At the optimum adsorption observed at lower pH values of 2.0 to 8.0, it is apparent that electrostatic interaction did not have much influence on paracetamol adsorption on the biosynthesized CuONPs.…”