Loading of zinc oxide nanoparticles from green synthesis on the low cost and eco-friendly activated carbon and its application for diazinon removal: isotherm, kinetics and retrieval study

Abstract

Diazinon (DZN) has been reported as an important pesticide with wide application in agriculture. The entry of these compounds into water resources has brought serious environmental problems due to their resistance to biodegradation; thus, this study was considered to be done to explore the process of DZN uptake and the influence of effective parameters. The study was performed experimentally and on a laboratory scale. Investigating the structure and morphology of the nanocomposite was done based on different analyses, i.e., FE-SEM, FTIR, and XRD. The experiments based on the Box–Behnken scheme were performed by surveying four important operating parameters (pH, contact time, nanocomposite dose, and DZN concentration). Optimization was performed by experiment design software and using the response surface method and analysis of the proposed model. The DZN removal efficiency was obtained 100% under optimal conditions including pH = 5, nanocomposite dose = 0.83 g/L, reaction time = 55 min, and DZN concentration = 5 mg/L. Considering the high correlation coefficient R2 = (0.9873) and $$R_{{{\text{Adj}}}}^{{2}}$$ R Adj 2 = (0.9725), the proposed model (quadratic) was approved. The results were indicative of conforming the reaction kinetic to the pseudo-second-order model and the correspondence of reaction isotherm to the Freundlich model (R2 = 0.997). Based on the obtained results, the adsorption process with AC–ZnO nanocomposite could be introduced as an efficient and eco-friendly technique to remove DZN.

Adsorptive removal of heavy metals from wastewater using Cobalt-diphenylamine (Co-DPA) complex

“…5 b). Different heavy metal ions may have different chemical affinities and ion exchange capacities concerning the chemical functional group on the surface of the adsorbent, which can explain differences in the percentage of different heavy metal ions eliminated at the same initial metal ions concentration, dose, and contact duration [ 30 , 47 , 48 , 74 , 75 ].

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“…As adsorption time progresses the active sites are occupied by adsorbates which make constant adsorption efficiency. This may be clarified by the fact that originally, the ion absorption rate was higher since entire sites on the adsorbent were unoccupied and the concentration of ions was high, but that rate remained constant as all sites were filled consequently because doing so prevents the additional adsorbate from being taken up [ 30 , 34 , 48 ].

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“…Figure 8 demonstrates the adsorption isotherm with fitting models. Adsorption isotherms are often used to explain equilibrium studies that provide the adsorbent's capacity and the equilibrium interactions between adsorbent and adsorbate [ 30 , 36 , 44 , 78 – 80 ]. Adsorption isotherms are the fraction of the quantity adsorbed and remaining in solution at set temperature as equilibrium.…”

“…Usually, heavy metal ions can be adsorbed on the surface of the adsorbent via intermolecular interactions. The amputation of heavy metals from numerous sources of wastewater has reportedly been accomplished using commercial activated carbon [ 15 , 29 , 30 ], zeolites, and biomass-derived adsorbents like peanut shells [ 31 – 33 ], banana peel [ 34 , 35 ], dry tree leaves [ 36 ], rice husk [ 37 ], tea and coffee waste [ 38 ], coconut shell powder [ 39 ], papaya seed [ 40 ], and eggshell [ 41 ]. Nevertheless, some problems, including the need for a prolonged reaction time, excessive calcination temperature, inadequate stability, short reusability, a low surface area, etc.…”

“…As a result, it is crucial to create low-cost adsorbents with a large surface area utilizing straightforward synthesis techniques. The characteristics of a promising ion adsorbent are high adsorption kinetics, substantial adsorption capacities even at low contamination levels, selectivity for the target ion, stability in the aqueous environment, scalability, recoverability, and cost [ 25 , 27 , 30 , 34 , 36 , 43 – 48 ]. Physical adsorption and chemical adsorption are the two main categories of adsorption processes [ 15 ].…”