Removal and extraction efficiency of Quaternary ammonium herbicides paraquat (PQ) from aqueous solution by ketoenol–pyrazole receptor functionalized silica hybrid adsorbent (SiNPz)

Abstract

Pesticides and herbicides have been used extensively in agricultural practices to control pests and increase crop yields. Paraquat (PQT 2+ , 1,1-dimethyl-4,4-dipyridinium chloride) is one of the herbicide that belois classified as bipyridines and is used over the world. The objective of this study is to use ketoenol–pyrazole receptor functionalized silica hybrid as adsorbent for removal PQT 2+ from aqueous solution. The adsorbent was synthesized, and characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), Thermal analysis and other techniques. Different experimental parameters such as the effect of the amount of adsorbent, solution pH and temperatures and contact times were studied. Pseudo-order kinetics models were studied, and our data followed a pseudo second order. Experimental data were analyzed for both Langmuir and Freundlich models and the data fitted well with the Langmuir isotherm model. To understand the mechanism of adsorption, thermodynamic parameters like standard enthalpy, standard Gibbs free energy, and standard entropy were studied. The study indicated that the process is spontaneous, exothermic in nature and follow physisorption mechanisms. The novelty of this study showed surface of pyrazol-enol-imine-substituted silica (SiNPz) has the ability to highlight the surface designed for efficient removal of PQT 2+ , from aqueous solutions more than other studies. The study also showed that ketoenol–pyrazole receptor can be regenerated in five cycles using HNO 3 without affecting its adsorption capacity.

Adsorption of Cationic Contaminants by Cyclodextrin Nanosponges Cross-Linked with 1,2,3,4-Butanetetracarboxylic Acid and Poly(vinyl alcohol)

“…Biological [6,7], physical [8,9], and chemical treatments [10,11] have all been informed in the previous studies for PQ removal. Different effective adsorbents were elaborated for PQ removal such as activated carbon [12], bentonite [13], bio-based material [14][15][16], carbon nanotubes [17], calixarene [18], cellulose nanofiber [19], cyclodextrin [20,21], graphene oxide [22], kaolin [23], magnetic adsorbent [24,25], microorganisms [26], montmorillonite [27], pillararene [28], and silica [29,30].…”

Novel family of bis-pyrazole coordination complexes as potent antibacterial and antifungal agents

“…24 Recent examples of iridium and platinum pyrazolate complexes demonstrated too highly promising activity in medical applications as in the case of anti-cancer agents. 25,26 Inspired by the observed structural diversity and wide range of applications, our group developed new pyrazolate derivatives 27,28 and investigated their efficiency in the coordination of transition metals. This research objective is actually the rst step in the construction of environmentally friendly hybrid silica-based materials for extraction of transition metals and purication of industrial waste water.…”

Adsorption of Paraquat by Poly(Vinyl Alcohol)-Cyclodextrin Nanosponges

“…Physical [ 12 , 13 ], biological [ 14 , 15 ], and chemical treatments [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ] have all been reported in the literature for PQ removal. An adsorption process has recently been investigated for PQ removal, which was applied for both organic and inorganic materials such as bio-based material [ 23 , 24 , 25 ], bentonite [ 26 , 27 ], microorganisms [ 28 ], activated carbon [ 29 , 30 ], kaolin [ 31 ], pillararene [ 32 , 33 ], calixarene [ 34 , 35 , 36 ], graphene oxide [ 37 ], carbon nanotubes [ 38 , 39 ], silica [ 40 , 41 ], magnetic adsorbent [ 42 , 43 ], montmorillonite [ 44 , 45 ], cellulose nanofiber [ 46 , 47 ], and cyclodextrin [ 48 ].…”