Paraquat Degradation by Biological Manganese Oxide (BioMnOx) Catalyst Generated From Living Microalga Pediastrum duplex AARL G060

Abstract

Paraquat is a non-selective fast-acting herbicide used to control weeds in agricultural crops. Many years of extensive use has caused environmental pollution and food toxicity. This agrochemical degrades slowly in nature, adsorbs onto clay lattices, and may require environmental remediation. Studies have shown that biosynthesized manganese oxide (BioMnO x) successfully degraded toxic synthetic compounds such as bis-phenol A and diclofenac, thus it has potential for paraquat degradation. In this experiment, P. duplex AARL G060 generated low (9.03 mg/L) and high (42.41 mg/L) concentrations of BioMnO x. The precipitated BioMnO x was observed by scanning electron microscopy (SEM), and the elemental composition was identified as Mn and O by energy-dispersive x-ray spectroscopy (EDS). The potential for BioMnO x to act as a catalyst in the degradation of paraquat was evaluated under three treatments: (1) a negative control (deionized water), (2) living alga with low BioMnO x plus hydrogen peroxide, and (3) living alga with high BioMnO x plus hydrogen peroxide. The results indicate that BioMnO x served as a catalyst in the Fenton-like reaction that could degrade more than 50% of the paraquat within 72 h. A kinetic study indicated that paraquat degradation by Fenton-like reactions using BioMnO x as a catalyst can be described by pseudo-first and pseudosecond order models. The pH level of the BioMnO x catalyst was neutral at the end of the experiment. In conclusion, BioMnO x is a viable and environmentally friendly catalyst to accelerate degradation of paraquat and other toxic chemicals.

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

“…Intraparticle diffusion model: Q t = k 3i t 0.5 (7) where Q t are the quantity of contaminant adsorbed (in mg/g) at time t, respectively, k 3i (g/mg•min 0.5 ) is adsorption rate constant, and t is contact time (min). Experiments were performed in triplicate.…”

“…This herbicide threatens both the environment [1,2] and health [3][4][5]. 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].…”

Engineered Manganese Redox Cycling in Anaerobic-Aerobic Mbbrs for Utilisation of Biogenic Manganese Oxides to Efficiently Remove Micropollutants

“…Mn(III&IV) oxides (MnOx, x between 1 and 2) can oxidise a large variety of organic compounds [1], owing to their relatively high redox potentials (500 and 600 mV). Biogenic manganese oxides (BioMnOx), i. e. MnOx generated by microorganisms [2,3], are thought to be among the strongest oxidants with low toxicity occurring in the natural environment [4]. Accordingly, BioMnOx-based technologies have attracted increasing attention as an effective solution to remove a wide range of pollutants in various matrices [5][6][7][8].…”

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

“…The appearance of this dangerous herbicide causes different negative effects on the environment [ 3 , 4 ] and heath [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. 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 ].…”