Plant extracts as an eco-friendly approach to remove paraquat from aqueous solution.

Nowadays, water pollution by herbicides is known as a global concern. Paraquat (PQ) (1-1-methyl-4,4-bi-pyridinium-dichloride) is a chip with high performance, which is being widely used herbicide to remove weeds from agricultural and natural ecosystems. PQ can contaminate water sources due to its high solubility in water. Human death by poisoning effects of PQ has been reported in several countries. Therefore, the side effects of PQ are a global challenge. This study aimed to investigate the bioremediation of PQ by plant extracts, as a low-cost, nontoxic, and natural absorbent to remove PQ from aqueous solutions in different conditions. In this regard, the extracts of common purslane (portulaca oleracea), florist kalanchoe (kalanchoe blossfeldiana), and jade plant (crassula portulaca) were used as adsorbents. For this purpose, the effect of various parameters such as contact time, initial concentration of PQ solution, temperature, pH, and amount of extract was investigated. The results of present study showed that P. oleracea extract and C. portulaca extracts have higher adsorption efficiency than k. blossfeldiana extract. The highest PQ removal was obtained by P. oleracea extract (79.04%) and C. portulaca extract (78.72%) at pH = 11, the adsorbent content of 0.2 mg L-1, and the lowest absorption of PQ (50.6%) was obtained by K. blossfeldiana extract. The highest PQ removal by plant extract was observed at 30 min for P. oleracea and C. portulaca, and at 15 min for k. blossfeldiana extract. Moreover, surface absorption capacity increased with increasing plant extract concentration, decreasing PQ concentration and decreased with increasing temperature. Finally, it can be concluded that plant extract can help to remove PQ from the aqueous solution.

Contamination of raw water with herbicides such as paraquat (PQ) is recognized as a problem in many countries. PQ is known as a chemical contaminant that is highly toxic with high water solubilities (620 g/l) among herbicides. Despite the ban on the use of PQ in some countries, due to its low price, high efficiency at low concentrations, and high speed of paraquat in suppressing weeds, today this herbicide is used to control a wide range of weeds in the world. In recent years, various approaches to removing PQ from the environment have been studied. Some of these methods are relatively time-consuming and expensive, with large amounts of sludge and hazardous by-products. Among the mentioned methods, the adsorption process shows the simplicity of operation, low-cost process, and high efficiency in removing PQ from water. Recently, many adsorbents have been developed to remove PQ from aqueous solutions, including biochar, activated carbon, chitosan and alginate, clay, rice husk, and bentonite. Plant extracts may be known as new adsorbent materials for removing PQ from water as an eco-friendly and economical process. Therefore, in this study we investigate the plant extracts performance as adsorbents in PQ removal from water.

Green, Sustainable Synthesis of γ-Fe2O3/MWCNT/Ag Nano-Composites Using the Viscum album Leaf Extract and Waste Car Tire for Removal of Sulfamethazine and Bacteria from Wastewater Streams.

Multi-walled carbon nanotubes (MWCNTs) decorated with Ag nanoparticles (NPs) are bifunctional adsorbent nanomaterials with antibacterial activity. They can be magnetically recovered from wastewater in case of coupling with γ-Fe2O3. In this study, for the first time, an environmentally friendly technique was applied to prepare a nanocomposite (NC) material composed of γ-Fe2O3/MWCNT/Ag by using Bridgestone disposable tires and Viscum album leaves extract. γ-Fe2O3/MWCNTs/Ag NC was employed for the removal of sulfamethazine (SMT) from aqueous solutions. Under the optimized conditions determined via the Taguchi method, the highest SMT adsorption capacity of the γ-Fe2O3/MWCNT/Ag NC was measured to be 47.6 mg/g. The experimental data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm. The thermodynamic parameters implied that the adsorption process was endothermic. In addition to adsorption of the drug pollutant, the NC demonstrated a superior antibacterial activity against Gram-positive bacteria. The reusability test also showed that over 79% SMT can be removed using γ-Fe2O3/MWCNTs/Ag NC even after four adsorption cycles. Taken together, γ-Fe2O3/MWCNTs/Ag NC was proven to be a promising antibacterial nano-adsorbent for wastewater treatment.

Removal of paraquat from aqueous solutions by plant extracts as an ecofriendly approach.

Paraquat is a very water-soluble herbicide widely used in agricultural and nonagricultural lands. The removal of paraquat from polluted water is very essential. Hence, three experiments were arranged separately to investigate the ability of plant extracts include Aloe vera, Portulaca grandiflora, kalanchoe daigremontiana, Sedum rubotinctum, Brassica rapa var. rapa, Helxine soleirolii, Brassica oleracea var. capitata, Crassula ovate, Aptenia cordifolia, Tradescantia albiflora to the removal of paraquat (PQ) from water. In the 1st experiment, High-performance liquid chromatography was used to determine the removal rate of PQ by using plant extracts. In the 2nd and 3rd experiments, PQ solutions were subjected to plant extracts treatments and then spray on the leaves of littleseed canarygrass (Phalaris minor) under greenhouse and field conditions, respectively. In general, the results of these experiments revealed that all plant extracts resulted in higher PQ removal from water compared to control. The maximum removal of PQ was observed at pH 11, 25 °C, 30 Min, and 0.2 mL in the presence of plant extracts. In the presence of P. grandiflora, C. ovate, k. daigremontiana, A. cordifolia, H. soleirolii, Aloe vera, S. rubotinctum, B. oleracea var. capitata, B. rapa var. rapa, and T. albiflora plant extracts, PQ removal from water increased to 68.34%, 65.45%, 63.97%, 59.81%, 59.29%, 55.44%, 52.06%, 50.34%, 48.86%, and 46.44% under normal conditions and 79.71%, 78.61%, 78.00%, 75.83%, 74.66%, 72.12%, 71.57%, 71.02%, 69.35%, and 68.73% under optimum conditions, respectively. Results of the 2nd and 3rd experiments were demonstrated a decrease in PQ performance on littleseed canarygrass control. It can be concluded that plant extracts can reduce the residual of PQ in water bodies.

Photocatalytic degradation of model pharmaceutical pollutant by novel magnetic TiO2@ZnFe2O4/Pd nanocomposite with enhanced photocatalytic activity and stability under solar light irradiation.

In the last decades, the use of magnetic nanocomposites as a catalyst was considered for removal of organic pollutants due to its easy separation. Therefore, initially, TiO2@ZnFe2O4/Pd nanocomposite was prepared and then used in the photodegradation of diclofenac under direct solar irradiation in the batch and continuous systems. The structure, morphology and other specifications of produced nanocatalyst were determined via XRD, VSM, FESEM/EDX, FTIR, GTA, UV-Vis, Zeta potential, XPS and ICP-OES. The effective factors on diclofenac removal via nanophotocatalyst viz. pH, catalyst concentration, initial concentration of diclofenac, and flow rate and column length on diclofenac photodegradation were studied. Based on the results, the optimal rate for pH, catalyst concentration, and initial concentration of diclofenac was 4, 0.03 g/l and 10 mg/l respectively. Pd-coated TiO2@ZnFe2O4 magnetic photocatalyst had higher photocatalytic activity in diclofenac photodegradation in relation to ZnFe2O4 and TiO2@ZnFe2O4 under solar light irradiation. The findings showed that after five recycles, the photocatalytic efficiency did not show much reduction i.e. the removal efficiency from 86.1% in the first cycle reduced only to 71.38% in the last cycle. Likewise, in this study, with flow rate reduction and column length increase diclofenac degradation rate increased.