Role of Fe3O4 magnetite nanoparticles used to coat bentonite in zinc(II) ions sequestration

Bio-adsorption of heavy metals from aqueous solution using the ZnO-modified date pits

The bio-adsorption of heavy metals (including Cu2+, Ni2+, and Zn2+) in aqueous solution and also in an industry wastewater using the ZnO-modified date pits (MDP) as the bio-adsorbent are investigated. The fresh and used bio-adsorbents were characterized by FT-IR, SEM, BET, and XRD. The bio-adsorption parameters (including the pH of solution, the particle size of MDP, the shaking speed, the initial concentration of heavy metals, the dosing of MDP, the adsorption time, and the adsorption temperature) were screened and the data were used to optimize the bio-adsorption process and to study the bio-adsorption isotherms, kinetics, and thermodynamics. Two adsorption models (Langmuir isotherm model and Freundlich isotherm model) and three kinetic models (pseudo-first-order model, pseudo-second-order model, and intra-particle diffusion model) were applied to model the experimental data. Results show that the maximum adsorption amount of Cu2+, Ni2+, and Zn2+ on a complete monolayer of MDP are 82.4, 71.9, and 66.3 mg g-1, which are over 4 times of those of date pits-based bio-adsorbents reported in literature. The bio-adsorption of heavy metals on MDP is spontaneous and exothermic, and is regulated by chemical adsorption on the homogeneous and heterogeneous adsorption sites of MDP surface. This work demonstrates an effective modification protocol for improved bio-adsorption performance of the date pits-based bio-adsorbent, which is cheap and originally from a waste.

Removal of lead ions using OA-Fe3O4 magnetic nanoparticles-based pickering emulsion liquid membrane: process optimization using box-behnken response surface methodology

The purpose of this study is to explore the pickering emulsion liquid membrane (PELM) performance for removing divalent lead ions (Pb II) from aqueous solution. In the present work, the membrane phase was prepared by dissolving methyltrioctylammonium chloride (Aliquat 336) with Mahua oil and adding oleic acid coated-ferrosoferric oxide (OA-Fe₃O₄) as magnetic nanoparticles. Experimental investigation on percentage removal of lead ions was carried out by studying the influencing process parameters such as pH, agitation speed, stripping concentration, initial feed concentration, surfactant concentration, treat ratio, M/S ratio and carrier concentration. The optimum condition to remove 98.52% of lead ions from the feed solutions has achieved at a stripping phase concentration of 0.3 M, treat ratio of 3, agitation speed of 300 rpm, initial feed concentration of 10 ppm and stabilizer concentration of 2 wt%. The experimental results were validated using box-behnken response surface methodology. The extraction ability of OA-Fe₃O₄ magnetic nanoparticles-based PELM has been evaluated using statistical optimization of all the affecting process factors using the design of the experiments.

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins, Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.

Bio-remediation approaches for alleviation of cadmium contamination in natural resources

Cadmium (Cd) is a harmful heavy metal that can cause potent environmental and health hazards at different trophic levels through food chain. Cd is relatively non-biodegradable and persists for a long time in the environment. Considering the potential toxicity and non-biodegradability of Cd in the environment as well as its health hazards, this is an urgent issue of international concern that needs to be addressed by implicating suitable remedial approaches. The current article specifically attempts to review the different biological approaches for remediation of Cd contamination in natural resources. Further, bioremediation mechanisms of Cd by microbes such as bacteria, fungi, algae are comprehensively discussed. Studies indicate that heavy metal resistant microbes can be used as suitable biosorbents for the removal of Cd (up to 90%) in the natural resources. Soil-to-plant transfer coefficient (TC) of Cd ranges from 3.9 to 3340 depending on the availability of metal to plants and also on the type of plant species. The potential phytoremediation strategies for Cd removal and the key factors influencing bioremediation process are also emphasized. Studies on molecular mechanisms of transgenic plants for Cd bioremediation show immense potential for enhancing Cd phytoremediation efficiency. Thus, it is suggested that nano-technological based integrated bioremediation approaches could be a potential futuristic path for Cd decontamination in natural resources. This review would be highly useful for the biologists, chemists, biotechnologists and environmentalists to understand the long-term impacts of Cd on ecology and human health so that potential remedial measures could be taken in advance.

The biosorption of reactive red dye onto orange peel waste: a study on the isotherm and kinetic processes and sensitivity analysis using the artificial neural network approach

The agricultural waste of orange peels (OPs) was utilized as a cheap biosorbent and then tested for its ability to treat the reactive red (RR) dye wastewater. Several experiments were done to get the equilibrium isotherm and kinetic-relevant data. In addition, several experimental factors such as solution pH, temperature, contact time, and initial RR dye concentration were studied, in light of their impact on the biosorption process. The utilized isotherm and kinetic models were evaluated by using the chi-square test and coefficient of determination parameters for their representation of real data. In addition, the obtained data of their biosorption capacities, at different conditions, were modeled by the artificial neural network (ANN) approach. The results of the isotherm study revealed that the experimental data can be best accounted by both the Langmuir and Temkin models, demonstrating that the RR molecules were sorbed to two or more different types of biosorption sites of OP. The kinetic study for determining the characteristics of the rate of diffusion demonstrated that the intraparticle diffusion process was not the sole rate-limiting step in the biosorption of the RR dye-OP couple. Furthermore, the biosorption process was chemisorption in nature, as the pseudo-second-order reaction proved to be the best representative model for the kinetic data. The outcome of modeling also assumed that using the ANN tool was useful to reproduce the data again and foretell the manner in which biosorption behaved. According to the results of the Langmuir model, it was found that the maximum OP uptake for the biosorption of the RR dye was up to 82 mg/g, observed at optimized values of the experimental parameters. Such prior results highlight that OP is an effective agent of biosorption in the elimination of RR dyes from polluted solutions, moreover, in a cost-effective manner.