A novel approach to preparation of nano-adsorbent from agricultural wastes (Saccharum officinarum leaves) and its environmental application

Biosynthesis and characterization of selenium nanoparticles from Andrographis alata: Assessment of their potential antimicrobial, antidiabetic, anti-Alzheimer's and wound healing properties

Recently, there has been a lot of focus on the environmentally friendly, specifically plant-based, synthesis of nanoparticles. The extract of leaves from Andrographis alata (A. alata) was used in the current work as a reducing agent to create selenium nanoparticles (SeNPs), which will be used in biological applications (antibacterial, antioxidant and antidiabetic, anti-Alzheimer's and wound healing properties). As part of detailed characterization, the UV-Vis spectra showed an absorption peak at 274 nm with a size in the range of 55-75 nm were shown in morphological investigations using EDS, DLS and SEM analysis to have crystalline spherical-shaped structures. Against several harmful bacterial strains, SeNPs demonstrated a remarkable antibacterial effectiveness. The minimum inhibitory concentration (MIC) of synthesized SeNPs completely prevented the development of various pathogens. Furthermore, bio-reduced SeNPs showed high cholinesterase inhibition efficacy and good antipotential Alzheimer's. According to the current research, treatment with biosynthesized SeNPs stimulates faster wound healing in NIH3T3 murine fibroblast cell lines without cytotoxicity. Different in vitro biological experiments also showed that, when compared with the extract of A. alata, bio-reduced SeNPs had considerable antibacterial, antioxidant effects, antidiabetic, anti-Alzheimer's and wound healing. In general, the findings demonstrate the efficacy and prospective therapeutic uses of SeNPs.

Effective Adsorptive Removal of Coomassie Violet Dye from Aqueous Solutions Using Green Synthesized Zinc Hydroxide Nanoparticles Prepared from Calotropis gigantea Leaf Extract

The removal of color from dye wastewater is crucial, since dyes are extremely toxic and can cause cancer in a variety of life forms. Studies must be done to use cost-effective adsorbents for the removal of color from dye effluents to protect the environment. To our knowledge, virtually no research has been done to describe the possibility of using Calotropis gigantea leaf extract zinc hydroxide nanoparticles (CG-Zn(OH)2NPs) as an adsorbent for the decolorization of Coomassie violet (CV) from the aqueous emulsion, either in batch mode or continuously. In the present batch investigation, CV dye is removed from the synthetic aqueous phase using CG-Zn(OH)2NPs as an adsorbent. The synthesized nanoparticles were characterized using various instrumental techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and Brunauer–Emmett–Teller (BET) surface area and pore volume, a particle size analyser, and zero-point charge. The decolorization efficacy of CV dye from an aqueous phase by the adsorbent was examined in batch mode by varying process parameters. The consequences of various experimental variables were optimized using response surface methodology (RSM) to achieve the maximum decolorization efficiency (90.74%) and equilibrium dye uptake, qe (35.12 mg g−1). The optimum pH, dye concentration, CG-Zn(OH)2NPs adsorbent dosage, and particle size were found to be 1.8, 225 mg L−1, 5 g L−1, and 78 μm, respectively for CV dye adsorption capacity at equilibrium. The adsorbent zero-point charge was found to be at pH 8.5. The Langmuir isotherm model provided a good representation of the equilibrium data in aqueous solutions, with a maximum monolayer adsorption capability (qmax) of 40.25 mg g−1 at 299 K. The dye adsorption rate follows a pseudo-second-order kinetic model at various dye concentrations, which indicated that the reaction is more chemisorption than physisorption. The negative values of ΔG and positive values of ΔH at different temperatures indicate that the adsorption process is spontaneous and endothermic, respectively. Reusability tests revealed that the prepared nanoparticles may be used for up to three runs, indicating that the novel CG-Zn(OH)2NPs seems to be a very promising adsorbent for the removal of Coomassie violet dye from wastewater.

Nano Modifications of Biochar to Enhance Heavy Metal Adsorption from Wastewaters: A Review

Biochar (BC) is a carbon-rich material that can be obtained by thermal decomposition of agricultural solid waste under oxygen-limited conditions. It has received increasing attention as a cost-effective sorbent to treat metal-contaminated water due to attributes such as high porosity and the presence of various functional groups. The heavy metal (HM) sorption and removal capacity of BC can be enhanced by developing novel biochar nanohybrids (BNHs) that can be produced via surface modification of BC with nanomaterials. Loading of nanomaterials on the biochar surface can improve its physicochemical properties through alterations in the functional group profile, porosity, and availability of active sites on the BC surface which can enhance the HM adsorption ability. This manuscript provides information on preparation of nano-based biochar hybrids emanating from the type of modifying agent for the removal of different HM ions from wastewaters, and the underlying mechanisms have been discussed. Further, this compilation discusses published literature depicting the influence of different processes of preparation on the physicochemical properties and adsorption capacity of nanobiochar hybrids. The potential risks of BNHs have been reviewed to effectively avoid the possible harmful impacts on the environment, and future research directions have been proposed.

Ordered Mesoporous Silica Prepared in Different Solvent Conditions: Application for Cu(II) and Pb(II) Adsorption

In this work, the synthesis of ordered mesoporous silica of MCM-41 type was investigated aimed at improving its morphology by varying the synthesis conditions in a one-pot process, employing different temperatures and solvent conditions. 2-methoxyethanol was used as co-solvent to ethanol. The co-solvent ratio and the synthesis temperature were varied. The pore morphology of the materials was characterized by nitrogen porosimetry and small angle neutron scattering (SANS), and the particle morphology by transmission electron microscopy (TEM) and ultra-small angle neutron scattering (USANS). The thermal behavior was investigated by simultaneous thermogravimetry-differential scanning calorimetry (TG-DSC) measurements. The SANS and N₂ sorption results demonstrated that a well-ordered mesoporous structure was obtained at all conditions in the synthesis at room temperature. Addition of methoxyethanol led to an increase of the pore wall thickness. Simultaneously, an increase of methoxyethanol content led to lowering of the mean particle size from 300 to 230 nm, according to the ultra-small angle scattering data. The ordered porosity and high specific surfaces make these materials suitable for applications such as adsorbents in environmental remediation. Batch adsorption measurements of metal ion removal from aqueous solutions of Cu(II) and Pb(II) showed that the materials exhibit dominantly monolayer surface adsorption characteristics. The adsorption capacities were 9.7 mg/g for Cu(II) and 18.8 mg/g for Pb(II) at pH 5, making these materials competitive in performance to various composite materials.

Biogenic and facile synthesis of selenium nanoparticles using Vaccinium arctostaphylos L. fruit extract and anticancer activity against in vitro model of breast cancer

Biogenic synthesis of selenium nanoparticles (SeNPs) using plant extracts has emerged as a promising alternative approach to traditional chemical synthesis. The current study aims to introduce a safe, low-cost, and green synthesis of SeNPs using fresh fruit extract of Vaccinium arctostaphylos L. The biogenic synthesis of SeNPs was confirmed by different analyses including ultraviolet-visible spectrophotometry, Fourier transform infrared, and energy-dispersive X-ray. Also, the crystalline nature, size, and morphology of the obtained SeNPs were characterized by X-ray diffraction, dynamic light scattering, field emission scanning electron microscopy, and transmission electron microscopy techniques. The SeNPs were successfully synthesized with fruit extract of V. arctostaphylos L. in a regular spherical form and narrow size distribution with suitable zeta-potential values and exhibited appropriate biocompatibility. It revealed that the synthesized SeNPs can significantly inhibit the growth of 4T1 breast cancer cells with an IC₅₀ of ∼84.19 ± 25.96 µg/ml after 72 h treatment. Overall, it can be concluded that the green synthesized SeNPs can be attractive, nontoxic, and eco-friendly candidates for drug delivery or medicinal applications.

Leachate treatment potential of nanomaterial based assemblies: a systematic review on recent development

Rapid development of the population has brought about a serious problem of waste generation and management. Open dumping and land filling are two of the preferred options for waste management and treatment. As a consequence of this, the accumulation of leachates has become one of the concerns for environmental sustainability. In this regard, various treatment methodologies have been developed in recent decades. Among them, the nanomaterial-based approaches are the emerging ones in the current scenario due to their various unique properties. Furthermore, nanomaterial-based assemblies (i.e., nanomaterials combined with microbes, chemical catalysts, enzymes, and so on) have been introduced as a novel modification for leachate treatment. This work, therefore, has been dedicated to comprehensively reviewing all nanomaterial based leachate treatment techniques. In this regard, the first part of this review will discuss the nano catalyst, nano adsorbent along with their synthesis and mechanistic view of pollutant removal potential. In the second part, the nanomaterial-based microbial conjugates applied in the leachate treatments have been discussed. Apart from this, various other nanomaterial-based methods have been discussed in the third part of the review. Hence this review is providing an insight of all the recent developments pertaining to the nano material based leachate treatment techniques.

A unique, inexpensive, and abundantly available adsorbent: composite of synthesized silver nanoparticles (AgNPs) and banana leaves powder (BLP)

The purpose of this study is to investigate the development of a new and inexpensive adsorbent by immobilization synthesized silver nanoparticles (AgNPs) onto banana leaves powder (BLP), and the prepared composite (BLP)/(AgNPs) was used as an adsorbent for Zn(II), Pb(II), and Fe(III) ion removal from aqueous solutions under the influence of various reaction conditions. (BLP)/(AgNPs) demonstrated remarkable sensitivity toward Zn (II), Pb (II), and Fe (III) ions; metal ions eliminations increased with increasing contact time, agitation speed, adsorbent dose, and temperature, yielding adequate selectivity and ideal removal efficiency of 79%, 88%, and 91% for Zn (II), Pb (II), and Fe (III) ions, respectively, at pH = 5 for Zn(II) and pH = 6 for Pb(II), and Fe(III). The equilibrium contact time for elimination of Zn (II), Pb (II), and Fe (III) ions was reaches at 40 min. Langmuir, Freundlich, and Temkin equations were used to test the obtained experimental data. Langmuir isotherm model was found to be more accurate in representing the data of Zn(II), Pb(II), and Fe(III) ions adsorption onto (BLP)/(AgNPs), with a regression coefficient (R² = 0.999) and maximum adsorption capacities of 190, 244, and 228 mg/g for Zn(II), Pb(II), and Fe(III) ions, respectively. The thermodynamic parameters proved that adsorption of metal ions is spontaneous, feasible, and endothermic, whereas Kinetic studies revealed that the process was best described by a pseudo second order kinetics.

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By reduction reaction, silver nanoparticles were impregnated in banana leaves homogeneous powder and used as an adsorbent.

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The fabricated composites are used as adsorbent for the removal of Zn (II), Pb (II), and Fe (III) ions from aqueous solutions.

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The new adsorbent exhibited high adsorption capacity with three metal ions and followed the order Pb (II)> Fe (III) >Zn (II) ions.

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The metal ions vanished from the solution within approximately 40 min.

Polypyrrole/zeolite composite - A nanoadsorbent for reactive dyes removal from synthetic solution

Synthetic dyes are among the common pollutants in the ecosystem. In the present study, polypyrrole/zeolite (PPy/Ze) nanocomposite was prepared and subsequently assessed for the removal of Reactive blue (RB) and Reactive red (RR) from synthetic solution. The polymeric PPy/Ze composite was synthesized by chemical oxidation of pyrrole in the presence of zeolite. Electron microscopic images (transmission and scanning) indicate that PPy/Ze nanocomposite was spherical in shape with an average size of 40-80 nm. The characteristic pyrrole and zeolite Fourier transform infrared spectrum peaks (1542 cm^-1, 1463 cm^-1, 1156 cm^-1, 1054 cm^-1, 879 cm^-1 and 756 cm^-1) in the nanocomposite confirmed zeolite integration with polypyrrole. Experimental variables such as PPy/Ze nanocomposite dose, initial RB and RR concentration, reaction temperature and pH were optimized. The PPy/Ze nanocomposite adsorbed 86.2% of RB and 88.3% of RR from synthetic solution at optimal conditions (pH 9, initial RR or RB concentration, 75 mg/l; PPy/Ze dose, 1.8 g/l; and temperature, 50 °C). Freundlich isotherm model and pseudo-second-order kinetics showed better fit for both RB and RR removal from synthetic solution. X-ray diffractogram confirmed the amorphous nature of PPy/Ze nanocomposite and that it was not altered even after dye adsorption. Adsorption-desorption studies showed that the composite has satisfactory adsorption potential for four cycles. The results show that the PPy/Ze nanocomposite could be used for the removal of dyes from wastewaters.

Efficient Removal of Heavy Metals from Aqueous Solutions through Functionalized γ-Graphyne-1 Membranes under External Uniform Electric Fields: Insights from Molecular Dynamics Simulations

Carbon-based nanosheet membranes with functionalized pores have great potential as water treatment membranes. In this study, the separation of Hg²⁺ and Cu²⁺ as heavy metal ions from aqueous solutions using a functionalized γ-graphyne-1 nanosheet membrane is investigated by molecular dynamics simulations. The simulation systems consist of a γ-graphyne-1 nanosheet with -COOH or -NH₂ functional groups on the edge of pores placed in an aqueous solution containing CuCl₂ and HgCl₂. An external electric field is applied as a driving force across the membrane for the separation of heavy metal ions using these functionalized pores. The ion-membrane and water molecule-membrane interaction energies, the radial distribution function of cations, the retention time and permeation of ions through the membrane, the density profile of water and ions, and the hydrogen bond in the system are investigated, and these results reveal that the performance of -NH₂-functionalized γ-graphyne-1 is better than that of -COOH-functionalized γ-graphyne-1 in the separation of Cu²⁺, while the Hg²⁺ cations encounter a high energy barrier as they pass through the membrane, especially in the -COOH-functionalized pore, due to their larger ionic radius and the smaller pore size of this membrane.

Preparation and in-vitro evaluation of mesoporous biogenic silica nanoparticles obtained from rice and wheat husk as a biocompatible carrier for anti-cancer drug delivery

In this study, mesoporous silica nanocarriers were synthesized from natural sources such as rice and wheat husk for drug delivery application. First, the biogenic silica in cereals husk was extracted by acid leaching and then converted to sodium silicate as a silica precursor. Mesoporous silica nanoparticles were then synthesized by adding sodium silicate to the template mixture by continuous and discrete modes during the sol-gel process. The effects of natural sources type and precursor addition method on nanocarriers' morphological and physicochemical properties were investigated by XRD, FT-IR, BET and SEM analysis. Our results showed rice husk-based spherical nanocarriers were more crystalline with slit-shaped pores, while wheat husk-based nanocarriers had been composed of spherical nanoparticles with narrow cylindrical pores. The results also showed that by adding the precursor discretely, their hydrophilicity, particle size and pore size increased compared with the continuous mode, probably due to the high initial concentration of the precursor in the reaction mixture. Doxorubicin (Dox), as a model anticancer drug was loaded into the nanocarriers, and the drug release behavior was studied at two different pH values (7.4 and 5.4). In general, the accumulated released drug at pH 5.4 was approximately twice as much as pH 7.4 due to the higher solubility of doxorubicin at acidic environment. Also, the accumulated released drug at pH 5.4 for nanocarriers which had been synthesized by discrete mode, was higher than continuous mode, due to the larger pore diameter of them. The biocompatibility and cytotoxicity of nanocarriers and Dox-loaded nanocarriers were also investigated on the HFF-2 and MCF-7 cell lines, respectively. Moreover, apoptosis, as the mechanism of cell death, was evaluated by morphological study of the MCF-7 cells. Within acceptable toxicity limits and apoptosis induction, the Dox-loaded nanocarriers, especially discrete mode synthesized nanocarriers, exhibited high-efficiency anticancer effect on the MCF-7 cell line.

Green synthesis of selenium nanoparticles mediated from Ceropegia bulbosa Roxb extract and its cytotoxicity, antimicrobial, mosquitocidal and photocatalytic activities

The present study is to design an eco-friendly mode to rapidly synthesize selenium nanoparticles (SeNPs) through Ceropegia bulbosa tuber's aqueous extracts and confirming SeNPs synthesis by UV-Vis spectroscopy, FT-IR, XRD, FE-SEM-EDS mapping, HR-TEM, DLS and zeta potential analysis. In addition, to assess the anti-cancer efficacy of the SeNPs against the cultured MDA-MB-231, as studies have shown SeNPs biosynthesis downregulates the cancer cells when compared to normal HBL100 cell lines. The study observed the IC₅₀ value of SeNPs against MDA-MB-231 cells was 34 µg/mL for 48 h. Furthermore, the SeNPs promotes growth inhibitory effects of certain clinical pathogens such as Bacillus subtilis and Escherichia coli. Apart, from this the SeNPs has shown larvicidal activity after 24 h exposure in Aedes albopitus mosquito's larvae with a maximum of 250 g/mL mortality concentration. This is confirmed by the histopathology results taken at the 4th larval stage. The histopathological studies revealed intense deterioration in the hindgut, epithelial cells, mid gut and cortex region of the larvae. Finally, tried to investigate the photocatalytic activity of SeNPs against the toxic dye, methylene blue using halogen lamp and obtained 96% degradation results. Withal computational study SeNPs was shown to exhibit consistent stability towards breast cancer protein BRCA2. Overall, our findings suggest SeNPs as a potent disruptive agent for MDA-MB-231 cells, few pathogens, mosquito larvae and boosts the photocatalytic dye degradation.

Plant celluloses, hemicelluloses, lignins, and volatile oils for the synthesis of nanoparticles and nanostructured materials

A huge variety of plants are harvested worldwide and their different constituents can be converted into a broad range of bionanomaterials. In parallel, much research effort in materials science and engineering is focused on the formation of nanoparticles and nanostructured materials originating from agricultural residues. Cellulose (40-50%), hemicellulose (20-40%), and lignin (20-30%) represent major plant ingredients and many techniques have been described that separate the main plant components for the synthesis of nanocelluloses, nano-hemicelluloses, and nanolignins with divergent and controllable properties. The minor components, such as essential oils, could also be used to produce non-toxic metal and metal oxide nanoparticles with high bioavailability, biocompatibility, and/or bioactivity. This review describes the chemical structure, the physical and chemical properties of plant cell constituents, different techniques for the synthesis of nanocelluloses, nanohemicelluloses, and nanolignins from various lignocellulose sources and agricultural residues, and the extraction of volatile oils from plants as well as their use in metal and metal oxide nanoparticle production and emulsion preparation. Furthermore, details about the formation of activated carbon nanomaterials by thermal treatment of lignocellulose materials, a few examples of mineral extraction from agriculture waste for nanoparticle fabrication, and the emerging applications of plant-based nanomaterials in different fields, such as biotechnology and medicine, environment protection, environmental remediation, or energy production and storage, are also included. This review also briefly discusses the recent developments and challenges of obtaining nanomaterials from plant residues, and the issues surrounding toxicity and regulation.

A POSS-Phosphazene Based Porous Material for Adsorption of Metal Ions from Water

The development of adsorptive materials continues to be an important area of research for removal of heavy metal ions from waste water. The adsorption capacity can be modulated by both physical and chemical modification of the adsorbent. Herein, we combine the unique properties of polyhedral oligomeric silsesquioxane (POSS) and organocyclophosphazene as the building units to synthesize a hybrid porous material, abbreviated as PN-POSS. The synthetic method follows a Heck reaction between hexa(4-bromophenoxy)cyclotriphosphazene and octavinylsilsesquioxane (OVS). The Brunauer-Emmett-Teller (BET) analysis shows that the material possesses micro- and mesopores of 1.5 and 3.8 nm size and a surface area on the order of 500 m²  g^-1 . These attributes in combination with the donor ability of the phosphazene units qualify the material for high adsorption of Pb²⁺ , Hg²⁺ and Cu²⁺ ions with maximal adsorption capacities on the order of 1326, 1927 and 2654 mg g^-1 , respectively. The adsorbent exhibits a good regeneration performance and can be effectively used for water treatment.

Agricultural waste

The management of agricultural waste has become very important because the inappropriate disposal yields negative effects on the environment. The resource recovery from agricultural waste which converts waste into available resources can reduce the waste and new resource consumption. This review summarizes the 2018 researches of over three hundred scholar papers from several aspects: agricultural waste, and, waste chemical characterization, agricultural waste material, adsorption, waste energy, composting, waste biogas, agricultural waste management, and others.