An innovative approach to synthesize graft copolymerized acetylacetone chitosan/surface functionalized alginate/rutile for efficient Ni(II) uptake from aqueous medium.

In this study, an innovative approach is followed to synthesize graft copolymerized chitosan with acetylacetone (AA-g-CS) through free-radical induced grafting. Afterwards, AA-g-CS and rutile have been intercalated uniformly into amino carbamate alginate matrix to prepare its biocomposite hydrogel beads of improved mechanical strength having different mass ratio i.e., 5.0 %, 10.0 % 15.0 % and 20.0 % w/w. Biocomposites have been thoroughly characterized through FTIR, SEM and EDX analysis. Isothermal sorption data showed good fit with Freundlich model as conferred from regression coefficient (R2 ≈ 0.99). Kinetic parameters were evaluated through non-linear (NL) fitting of different kinetic models. Experimental kinetic data exhibited close agreement to quasi-second order kinetic model (R2 ≈ 0.99) which reveals that chelation between heterogeneous grafted ligands and Ni(II) is occurring through complexation. Thermodynamic parameters were evaluated at different temperatures to observe the sorption mechanism. The negative values of ΔG° (-22.94, -23.56, -24.35 and - 24.94 kJ/mol), positive ΔH° (11.87 kJ/mol) and ΔS° (0.12 kJ/molK-1) values indicated that the removal process is spontaneous and endothermic. The maximum monolayer sorption capacity (qm) was figured as 246.41 mg/g at 298 K and pH = 6.0. Hence, 3AA-g-CS/TiO2 could be better candidate for economic recovery of Ni(II) ions from waste effluents.

Fe-POM/attapulgite composite materials: Efficient catalysts for plastic pyrolysis.

This article describes the catalytic cracking of low-density polyethylene over attapulgite clay and iron substituted tungstophosphate/attapulgite clay (Fe-POM/attapulgite) composite materials to evaluate their suitability and performance for recycling of plastic waste into liquid fuel. The prepared catalysts enhanced the yield of liquid fuel (hydrocarbons) produced in cracking process. A maximum yield of 82% liquid oil fraction with a negligible amount of coke was obtained for 50% Fe-POM/attapulgite composite. Whereas, only 68% liquid oil fractions with a large amount of solid black residue was produced in case of non-catalytic pyrolysis. Moreover, Fe-POM/attapulgite clay composites showed higher selectivity towards lower hydrocarbons (C5-C12) with aliphatic hydrocarbons as major fractions. These synthesised composite catalysts significantly lowered the pyrolysis temperature from 375°C to 310°C. Hence, recovery of valuable fuel oil from polyethylene using these synthesised catalysts suggested their applicability for energy production from plastic waste at industrial level as well as for effective environment pollution control.

Occurrence, toxic effects, and mitigation of pesticides as emerging environmental pollutants using robust nanomaterials - A review.

Increasing demand of food and agriculture is leading us towards the increasing use and introduction of pesticides to the environment. The upright increase of pesticides in water and associated adverse effects have become a great point of concern to develop proficient methods for their mitigation from water. Various different methods have been traditionally employed for this purpose. Recently, nanotechnology has turned out to be the field of prodigious interest for this purpose, and various specific methods were developed and employed to remove pesticides from water. In this study, nanotechnological methods such as adsorption and degradation have been thoroughly discussed along with their applications and limitations where different types of nanoparticles, nanocomposites, nanotubes, and nanomembranes have played a vital role. However, in this study the most commonly adopted method of adsorption is considered to be the better technique due to its low cost, efficiency, and ease of operation. The adsorption kinetic models were described to explain the efficiency of the nano-adrsorbants in order to evaluate the mass transfer processes. However, various degradation methodologies including photocatalysis and catalytic reduction have also been elaborated. Numerous robust metal, metal oxide and functionalized magnetic nanomaterials have been emphasized, categorized, and compared for the removal of pesticides from water. Additionally, current challenges faced by researchers and future directions have also been provided.

Modified alginate-chitosan-TiO2 composites for adsorptive removal of Ni(II) ions from aqueous medium.

In this study, organo-funtionalization of sodium-alginate has been carried out using phenylsemicarbazide as modifier to graft N, O-donor atoms containing functional groups (amino-carbamate moieties) to offer novel support for TiO2 immobilization. Hybrid composite made of aminocarbamated alginate, carboxymethyl chitosan (CMC) and titanium oxide TiO2 (MCA-TiO2) was prepared for the promising adsorptive remediation of Ni(II). FT-IR, SEM-EDX were employed to characterize MCA-TiO2. The optimization of TiO2 to modified alginate mass ratio was carried out and hydrogel beads with TiO2/MCA mass ratio of 10.0% (2MCA-TiO2) revealed highest sorption efficiency. The produced sorbents were adapted in the form of hydrogel beads for operation. Organic functionalization based on aminocarbamate (OCONHNH2) moieties on linear chains of alginate embedded additional chelating functional sites which enhanced sorption and selectivity. Batch mode experiments were conducted for optimization of pH and sorbent dose. Equilibrium sorption, kinetic and thermodynamic studies were performed to pattern the nature of sorption. Kinetic data was found in close agreement with pseudo-second order rate expression (PSORE). Isothermal equilibrium sorption data was well fitted with Langmuir adsorption model. Maximum sorption capacity was evaluated as 229 mg/g at 298 K and pH = 6.0.

Green synthesis of zinc ferrite nanoparticles for photocatalysis of methylene blue.

In this study, zinc ferrite nanoparticles (ZF-NPs) were synthesized using aqueous seed extract of Piper nigrum as a bio-reducing and stabilizing agent. FTIR, SEM, FE-SEM, XRD, and TGA have been used for characterizing ZF-NPs. The results showed that Piper nigrum stabilized ZF-NPs have high purity and size range of 60-80 nm. The performance of the ZF-NPs has been investigated by photocatalytic reduction of methylene blue (MB) in the presence of sunlight. The factors responsible for affecting the degradation values of the reaction were also explored for developing a better understanding of the phenomenon.

Environmentally benign extraction of cellulose from dunchi fiber for nanocellulose fabrication.

In the current study, cellulose was extracted from the plant dunchi fiber by using an ecofriendly method followed by preparation of nanocellulose. The procedure involved an alkali treatment and chlorine-free bleaching for removal of lignin and hemicelluloses from material. Fourier transform infrared (FTIR) spectroscopy provided the evidence about removal of hemicellulose and lignin. The morphological changes in the surface of lignocellulosic fibers were studied through scanning electron microscopy (SEM). X-ray Diffraction (XRD) analysis measured the degree of crystallinity of extracted cellulosic material. By using Segal method, the degree of crystallinity was found 66.7%. Crystal thickness was determined by Scherrer equation and its value was found to be 40.07 Å. The values were closed to the values observed for commercial microcrystalline cellulose (MCC). The TGA curve showed the thermal degradation pattern of the cellulosic material and it was closed to the thermal behavior of pure cellulose. Finally, nanocellulose was produced by acid hydrolysis from the obtained cellulosic material. Transmission electron microscopy (TEM) showed the existence of nanocellulose with an average aspect ratio of 10.45 ± 3.44. In the future, dunchi fiber has a potential to be used as a renewable source to produce cellulose and subsequently its nanocellulose for a wide range of applications in composite materials.

Fabrication of a novel hybrid biocomposite based on amino-thiocarbamate derivative of alginate/carboxymethyl chitosan/TiO2 for Ni(II) recovery.

A novel hybrid biocomposite based on amino-thiocarbamate derivative of alginate, carboxymethyl chitosan and TiO2 (TiO2/TSC-CMC) was fabricated and characterized using Fourier transform Infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX). The TiO2/TSC-CMC mass ratio (5.0-30.0%) was optimized and 3TiO2/TSC-CMC (hydrogel beads with TiO2/TSC-CMC mass ratio of 20.0%) was selected as the best sorbent for effective biosorption of Ni(II). Batch sorption experiments were conducted, instantaneous and equilibrium sorption capacities were investigated as function of pH, sorbent dose, initial metal concentration, contact time and temperature. Kinetic data could be well explained through pseudo second order rate equation (PSORE) depicting that the rate determining step involves the transfer of electron density from sorbent functional sites to central metal ion. Langmuir model fitted well with isothermal sorption data and maximum monolayer sorption capacity (qm) was computed as 172 mg/g at pH 6.0 and temperature 298 K. The values of thermodynamic parameters such as standard enthalpy change (16.94 kJ/mol) and standard Gibbs energy change (-18.67, -19.48, -20.57, and -21.38 kJ/mol) and standard entropy change (0.12 kJ/mol·K) concluded that sorption process is endothermic, spontaneous and resulted with increase in randomness. Hence, 3TiO2/TSC-CMC was found efficient and reusable sorbent.

Potential perspectives of biodegradable plastics for food packaging application-review of properties and recent developments.

Potential hazardous effects caused by non-biodegradable plastics are considered to be one of the most widely discussed and notable challenges of the 21st century. To address this particular problem, immense efforts have been devoted to the preparation of biodegradable plastics material. This green approach mitigates the major drawbacks e.g. improper waste management, low degradation rates, waste accumulation in water reservoirs and harmful chemical reagents hence providing a natural, economical and biodegradable alternative to the customarily employed non-biodegradable plastics. This review provides an insight into recently engineered biodegradable plastics used for packaging applications. Properties such as barrier/permeation indexes, thermal, electrical and mechanical characteristics of the biodegradable plastics are considered in detail for developing an understanding regarding the fundamentals of biodegradable materials. Recent literature (2010-2018) was classified according to the composition and nature of the used material. Materials such as polylactic acid, polyhydroxyalkanoates, polyhydroxybutyrate, polycaprolactone, starch and cellulose were comprehensively discussed along with their properties and blending agents.

Benzocaine: Review on a Drug with Unfold Potential.

Benzocaine is well-known for its role as an anesthetic agent and largely used in oral ulcers, ear pain and dental complications. Along with lidocaine and other local anesthetics, benzocaine has marked it as an anesthetic agent in surgical procedures and as Na+ channels blocker, as well. Analogues of benzocaine have been found to possess biological potentials including antibacterial, antifungal and anti-cancer. Some derivatives were found to have conspicuous action against tuberculosis. The current review focuses to explore the century-long potential of the molecule and its analogs that have appeared in the literature. Furthermore, highlighting the biological potential of benzocaine and its analogues shall open-up new dimensions of future research to design more potent analogues.

Amino-carbamate moiety grafted calcium alginate hydrogel beads for effective biosorption of Ag(I) from aqueous solution: Economically-competitive recovery.

In present study, pure and amino-carbamate moiety grafted calcium alginate hydrogel beads (CA, PSC-CA) were prepared for their biosorption performance in the recovery of silver ions. The produced sorbents were characterized using FTIR, SEM, EDX and TGA. FTIR and SEM-EDX confirmed the successful modification and loading of silver ions onto hydrogel beads. When compared with CA, PSC-CA showed enhanced sorption but comparable kinetics. Equilibrium sorption studies showed that pH, sorbent dose, contact time and adsorbate concentration influenced the sorption capacity. The uptake kinetic data was well demonstrated by pseudo second order rate equation (PSORE). Elovich equation and the resistance to intra-particle diffusion model (RID) suggested that there were two phases of sorption, first one was rapid followed by relatively slow uptake step. Equilibrium isothermal sorption data was well fitted by Langmuir and Sips models. The separation factor RL was found as 0 < RL < 1 which indicated favourable sorption. The maximum monolayer sorption capacity was computed as 210 mg/g at 298 K. Thermodynamic studies revealed the sorption process to be spontaneous and exothermic. PSC-CA hydrogel beads were found as cost-effective and efficient sorbent for economically-competitive recovery of Ag(I).

Nanocatalytic Assemblies for Catalytic Reduction of Nitrophenols: A Critical Review.

Nitrophenol is common carcinogenic pollutant known for its adverse effects on human beings and aquatic life. During the last few decades, the chemical reduction of nitrophenol compounds has been widely reported as the advanced removal methodology for such hazardous dyes from aqueous reservoirs. Many researchers have utilized different nanocatalytic systems using sodium borohydride (NaBH4) as the reducing agent for acquiring industrially useful reduction product of aminophenol by carrying out the chemical reduction of nitrophenols. Polymeric material supported monometallic nanoparticles are widely reported catalyst for the degradation of 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP). This review critically discusses the pros and cons of numerous supporting mediums of nanocatalytic assemblies used for the immobilization of nanomaterials. Mechanism and kinetic analysis of the reduction reaction of 2-NP and 4-NP have also been explained in this study. In addition, recent literature has also been effectively summarized in the tabular form for developing a better understanding of the reader. Pictorial representation of key nanocatalytic assemblies and catalytic reduction mechanism has also been narrated in this study.

Critical review on the chemical reduction of nitroaniline.

Conversion of nitroaniline (NA), a highly toxic pollutant that has been released into aquatic systems due to unmanaged industrial development in recent years, into the less harmful or a useful counterpart is the need of the hour. Various methods for its conversion and removal have been explored. Owing to its nominal features of advanced effectiveness, the chemical reduction of 4-NA using various different nanocatalytic systems is one such approach that has attracted tremendous interest over the past few years. The academic literature has been confined to case studies involving silver (Ag) and gold (Au) nanoparticles, as these are the two most widely used materials for the synthesis of nanocatalytic assemblies. Focus has also been given to sodium borohydride (NaBH4), which is used as a reductant during the chemical reduction of NA. This systematic review summarizes the fundamentals associated with the catalytic degradation of 4-NA, and presents a comprehensive and critical study of the latest modifications used in the synthesis of these catalytic systems. In addition, the kinetics, mechanisms, thermodynamics, as well as the future directions required for understanding this model reaction, have been provided in this particular study.

Innovative Seizure of Metal/Metal Oxide Nanoparticles in Water Purification: A Critical Review of Potential Risks.

Water contamination is a worldwide critical issue for the present society to avoid competition and maintain an environmentally friendly scenario. Removal of various pollutants including inorganic and organic compounds from water is a big challenge nowadays. Worldwide attention to promote polluted water and technologies related to its treatment has been adversely increased. The utilization of metal/metal oxide nanoparticles (NPs) for this purpose has gained much attention due to its exceptional properties imparted by reduced size and effective surface area. Moreover, metal/metal oxide NPs-based innovation for improved expulsion productivity is an ingenious area for research and development but the use of such NPs presents some serious risks. Herein, the advanced requisition of NPs for polluted water treatment is highlighted along with the difficulties related to them and their toxic impacts when used as water purifiers. Additionally, the plausible fate of metal/metal oxide NPs incorporated in the water for purification and salient future challenges are deliberated.

Selection of Optimum Strategies for the Fabrication of Plant-Mediated Metal Nanoparticles: Emerging Problems in Sustainability.

The green fabrication of nanoparticles (NPs) by using plants as reducing and capping agents involves energy efficient, less toxic, safer and simpler pathways. These pathways have been related to the rational use of numerous substances in fabrication of NPs and synthetic strategies, which have been mainly discussed in this article. The subject matter of this review is to discuss how a chemist can follow the green chemistry principles in terms of selection of substances and protocols used for NPs fabrication. Furthermore, it describes how a researcher can modify the physical properties of NPs by varying the reaction conditions. In short, this review article provides a scheme for the synthesis of NPs from selection of suitable plant to characterization of formed NPs by employing green chemistry.

Green Adeptness in the Synthesis and Stabilization of Copper Nanoparticles: Catalytic, Antibacterial, Cytotoxicity, and Antioxidant Activities.

Copper nanoparticles (CuNPs) are of great interest due to their extraordinary properties such as high surface-to-volume ratio, high yield strength, ductility, hardness, flexibility, and rigidity. CuNPs show catalytic, antibacterial, antioxidant, and antifungal activities along with cytotoxicity and anticancer properties in many different applications. Many physical and chemical methods have been used to synthesize nanoparticles including laser ablation, microwave-assisted process, sol-gel, co-precipitation, pulsed wire discharge, vacuum vapor deposition, high-energy irradiation, lithography, mechanical milling, photochemical reduction, electrochemistry, electrospray synthesis, hydrothermal reaction, microemulsion, and chemical reduction. Phytosynthesis of nanoparticles has been suggested as a valuable alternative to physical and chemical methods due to low cytotoxicity, economic prospects, environment-friendly, enhanced biocompatibility, and high antioxidant and antimicrobial activities. The review explains characterization techniques, their main role, limitations, and sensitivity used in the preparation of CuNPs. An overview of techniques used in the synthesis of CuNPs, synthesis procedure, reaction parameters which affect the properties of synthesized CuNPs, and a screening analysis which is used to identify phytochemicals in different plants is presented from the recent published literature which has been reviewed and summarized. Hypothetical mechanisms of reduction of the copper ion by quercetin, stabilization of copper nanoparticles by santin, antimicrobial activity, and reduction of 4-nitrophenol with diagrammatic illustrations are given. The main purpose of this review was to summarize the data of plants used for the synthesis of CuNPs and open a new pathway for researchers to investigate those plants which have not been used in the past. Graphical abstract Proposed Mechanism for Antibacterial activity of copper nanoparticles.

Comparative study of different activation treatments for the preparation of activated carbon: a mini-review.

In this review, various methods of preparation of activated carbon from agricultural and commercial waste material are reviewed. In addition, we also discuss various activation treatments using a comparative approach. The data are organised in tabulated form for ease of comparative study. A review of numerous characterisation techniques is also provided. The effect of time and temperature, activation conditions, carbonisation conditions and impregnation ratios are explained and several physical and chemical activation treatments of raw materials and their impact on the micro- and mesoporous volumes and surface area are discussed. Lastly, a review of adsorption mechanisms of activated carbon (AC) is also provided.

Microwave treated Salvadora oleoides as an eco-friendly biosorbent for the removal of toxic methyl violet dye from aqueous solution--A green approach.

In the present study, microwave treated Salvadora oleoides (MW-SO) has been investigated as a potential biosorbent for the removal of toxic methyl violet dye. A batch adsorption method was experimented for biosorptive removal of toxic methyl violet dye from the aqueous solution. The effect of various operating variables, viz., adsorbent dosage, pH, contact time and temperature on the removal of the dye was studied and it was found that nearly 99% removal of the dye was possible under optimum conditions. Kinetic study revealed that a pseudo-second-order mechanism was predominant and the overall process of the dye adsorption involved more than one step. Hence, in order to investigate the rate determining step, intra-particle diffusion model was applied. Adsorption equilibrium study was made by analyzing Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) adsorption isotherm models and the biosorption data was found to be best represented by the Langmuir model. The biosorption efficiency of MW-SO was also compared with unmodified material, Salvadora oleoides (SO). It was found that the sorption capacity (qmax) increased from 58.5 mg/g to 219.7 mg/g on MW treatment. Determination of thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) confirmed the spontaneous, endothermic and feasible nature of the adsorption process. The preparation of MW-SO did not require any additional chemical treatment and a high percentage removal of methyl violet dye was obtained in much lesser time. Thus, it is in agreement with the principles of green chemistry. The results of the present research work suggest that MW-SO can be used as an environmentally friendly and economical alternative biosorbent for the removal of methyl violet dye from aqueous solutions.

Adsorption optimization of lead (II) using Saccharum bengalense as a non-conventional low cost biosorbent: isotherm and thermodynamics modeling.

In the present study a novel biomass, derived from the pulp of Saccharum bengalense, was used as an adsorbent material for the removal of Pb (II) ions from aqueous solution. After 50 minutes contact time, almost 92% lead removal was possible at pH 6.0 under batch test conditions. The experimental data was analyzed using Langmuir, Freundlich, Timken and Dubinin-Radushkevich two parameters isotherm model, three parameters Redlich-Peterson, Sip and Toth models and four parameters Fritz Schlunder isotherm models. Langmuir, Redlich-Peterson and Fritz-Schlunder models were found to be the best fit models. Kinetic studies revealed that the sorption process was well explained with pseudo second-order kinetic model Thermodynamic parameters including free energy change (AG degrees), enthalpy change (AH degrees) and entropy change (AS degrees) have been calculated and reveal the spontaneous, endothermic and feasible nature of the adsorption process. The thermodynamic parameters of activation (deltaG(#), deltaH(#) and deltaS(#)) were calculated from the pseudo-second order rate constant by using the Eyring equation. Results showed that Pb (II) adsorption onto SB is an associated mechanism and the reorientation step is entropy controlled.

Biosorption potentials of a novel green biosorbent Saccharum bengalense containing cellulose as carbohydrate polymer for removal of Ni (II) ions from aqueous solutions.

In this research work, the potential of a novel green material obtained from Saccharum bengalense (SB) plant was investigated for the removal of Ni (II) ions from aqueous solution. Biomaterial SB composed of cellulose macromolecules and was used without any chemical treatment. Batch experiments were performed by considering the effect of contact time, SB concentration, pH of the solution and temperature. Results revealed that ∼87% of Ni was removed from aqueous solution at optimum conditions. Three typical kinetic models namely, pseudo first order, pseudo second order and Elovich equations were applied to interpret the kinetic data. To investigate the rate determining step, the intra-particle diffusion model was applied on the experimental data. The sorption process was well explained with pseudo second-order kinetic model. Adsorption isothermal data was examined by applying classical two parameters (Langmuir, Freundlich, Timken and Dubinin-Radushkevich) and three parameters (Redlich-Peterson, Toth and Sips models) and four parameters Fritz Schlunder Isotherm models. Based on R(2) and χ(2) the equilibrium sorption data was better fitted to Langmuir and Sips isotherm model than any other model. Thermodynamics parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated respectively, which revealed the spontaneous, endothermic and feasible nature of adsorption process. The results of the present investigation suggest that S. bengalense can be used as an environmentally benign and low cost biomaterial for nickel removal from aqueous solution.