Fast and efficient removal of Pb(II) ion and malachite green dye from wastewater by using magnetic activated carbon-cobalt nanoparticles

Removal of heavy metal ions with magnetic carbon prepared from corncob biomass

Four novel magnetic-activated carbons (MACs) were prepared, characterised, and used as adsorbents to remove heavy metal ions from wastewater samples. The MACs prepared, are advanced adsorbents for the removal of Hg(II), Cr(III), Cd(II), and Pb(II). The nature of the acid, amount, composition of the MACs, and the remotion time were evaluated in aqueous solutions. The ions removal percentages obtained, under the best conditions, were 93% for Hg(II) and higher than 99% for Pb(II), Cr(III), and Cd(II) (100 mg L-1, initial concentration in solution), with 100 mg of the MAC-3 in HNO3 3 mM. The capacity of the best adsorbent, MAC-3, for removing heavy metals ions Hg(II), Cr(III), Cd(II), and Pb(II) was studied using Langmuir and Freundlich adsorption isotherms under the best condition. The maximum adsorption capacities of Hg(II), Cr(III), Cd(II), and Pb(II) were found to be 10.72, 11.51, 11.49 and 11.49 mg g-1, the values of constants of Freundlich models were 17.98, 26.83, 9.18, and 7.18 mg g-1 respectively. For Hg(II) and Pb(II) the correlation factor (R2) was better for Freundlich model, while Cr(III) and Cd(II) showed better R2 with Langmuir model. Finally, the treatment for the elimination of heavy metal ions was carried out, with wastewater samples of industrial and domestic origin, and used for crop irrigation. The samples were collected in Irrigation District 003, Hidalgo, Mexico. The MAC-3 removes heavy metal ions from the wastewater matrix above 99%.

Adsorptive removal of heavy metals from wastewater using Cobalt-diphenylamine (Co-DPA) complex

Heavy metals like Cadmium, Lead, and Chromium are the pollutants emitted into the environment through industrial development. In this work, a new diphenylamine coordinated cobalt complex (Co-DPA) has been synthesized and tested for its efficiency in removing heavy metals from wastewater, and its adsorption capacity was investigated. The effectiveness of heavy metals removal by Co-DPA was evaluated by adjusting the adsorption parameters, such as adsorbent dose, pH, initial metals concentration, and adsorption period. Heavy metal concentrations in real sample were 0.267, 0.075, and 0.125 mg/L for Cd2+, Pb2+, and Cr3+ before using as-synthesized Co-DPA to treat wastewater. After being treated with synthesized Co-DPA the concentration of heavy metals was reduced to 0.0129, 0.00028, 0.00054 mg/L for Cd2+, Pb2+, and Cr3+, respectively, in 80 min. The removal efficiency was 95.6%, 99.5%, and 99.5% for the respective metals. The adsorption process fitted satisfactorily with Freundlich isotherm with R2(0.999, 0.997, 0.995) for Cd2+, Pb2+, and Cr3+, respectively. The kinetic data obeyed the pseudo-second order for Cd2+ and Cr2+ and the pseudo-first order for Pb2+. Based on the results obtained within the framework of this study, it is concluded that the as-synthesized Co-DPA is a good adsorbent to eliminate heavy metal ions like Cd2+, Pb2+, and Cr3+from wastewater solution. In general, Co-DPA is a promising new material for the removal of heavy metal ions from water.

Optimization of adsorption performance of cerium-loaded intercalated bentonite by CCD-RSM and GA-BPNN and its application in simultaneous removal of phosphorus and ammonia nitrogen

Excessive phosphorus (P) and ammonia nitrogen (NH₃-N) in water bodies can lead to eutrophication of the aquatic environment. Therefore, it is important to develop a technology that can efficiently remove P and NH₃-N from water. Here, the adsorption performance of cerium-loaded intercalated bentonite (Ce-bentonite) was optimized based on single-factor experiments using central composite design-response surface methodology (CCD-RSM) and genetic algorithm-back propagation neural network (GA-BPNN) models. Based on the determination coefficient (R²), mean absolute error (MAE), mean square error (MSE), mean absolute percentage error (MAPE), and root mean square error (RMSE), the GA-BPNN model was found to be more accurate in predicting adsorption conditions than the CCD-RSM model. The validation results showed that the removal efficiency of P and NH₃-N by Ce-bentonite under optimal adsorption conditions (adsorbent dosage = 1.0 g, adsorption time = 60 min, pH = 8, initial concentration = 30 mg/L) reached 95.70% and 65.93%. Furthermore, based on the application of these optimal conditions in simultaneous removal of P and NH₃-N by Ce-bentonite, pseudo-second order and Freundlich models were able to better analyze adsorption kinetics and isotherms. It is concluded that the optimization of experimental conditions by GA-BPNN has some guidance and provides a new approach to explore adsorption performance after optimizing the conditions.

Dual-functional marine algal carbon-based materials with highly efficient dye removal and disinfection control

The design and simple, green preparation of dual-functional materials for the decontamination of both hazardous dyes and pathogenic microorganisms from wastewater remain challenging currently. Herein, a promising marine algal carbon-based material (named C-SA/SP) with both highly efficient dye adsorptive and antibacterial properties was fabricated based on the incorporation of sodium alginate and a low dose of silver phosphate via a facile and eco-friendly approach. The structure, removal of malachite green (MG) and congo red (CR), and their antibacterial performance were studied, and the adsorption mechanism was further interpreted by the statistical physics models, besides the classic models. The results show that the maximum simulated adsorption capacity for MG reached 2798.27 mg/g, and its minimal inhibit concentration for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was 0.4 mg/mL and 0.2 mg/mL, respectively. The mechanistic study suggests that silver phosphate exerted the effects of catalytic carbon formation and pore formation, while reducing the electronegativity of the material as well, thus improving its dye adsorptive performance. Moreover, the MG adsorption onto C-SA/SP showed vertical orientation and a multi-molecular way, and its adsorption sites were involved in the adsorption process with the increase of temperature. Overall, the study indicates that the as-made dual-functional materials have good applied prospects for water remediation.

Adsorption of acid fuchsine dye from wastewater by Mg-ferrite particles

Adsorption is a widely applied waste water treatment technology, especially for removing micro-pollutants and dyes of industrial effluents. Over the past decade, adsorbing metal oxide micron- and nano-particles have been successfully developed and investigated as adsorbents. In the present research, Mg-ferrite adsorbent particles were synthesized and their properties were fully determined. The pore volume is 0.139 cm³/g. The BET analysis reveals a surface area of 94.4 m²/g. The porosity is of meso- and microporous nature. The adsorbent was used to adsorb acid fuchsine, an important industrial dye. The equilibrium adsorption capacity was 796.4 mg/g, with an adsorption yield of 78.7-82.0%. The adsorption kinetics can be adequately fitted by a pseudo-second-order model. The isotherms of both Langmuir and Freundlich are applicable. The stability, recovery and reuse of the ferrite particles were proven in multi-cycle experiments, and the adsorption activity decreased by less than 3% between the first and fifth cycle. Experimental and fitting results were finally used to design a batch adsorber to remove a given concentration of acid fuchsine from different volumes of wastewater.

Plant-mediated synthesis of silver-doped zinc oxide nanoparticles and evaluation of their antimicrobial activity against bacteria cause tooth decay

In this research, silver-doped zinc oxide (SdZnO) nanoparticles (NPs) were synthesized in an environmental-friendly manner. The synthesized NPs were identified by UV-vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Finally, the antimicrobial activity of synthesized ZnO and SdZnO NPs was performed. It was observed that by doping silver, the size of ZnO NPs was changed. By adding silver to ZnO NPs, the antimicrobial effect of ZnO NPs was improved. Antibacterial test against gram-positive bacterium Streptococcus mutants showed that SdZnO NPs with a low density of silver had higher antibacterial activity than ZnO NPs; Therefore, SdZnO NPs can be used as a new antibacterial agent in medical applications.

Adsorption of Malachite Green and Pb2+ by KMnO4-Modified Biochar: Insights and Mechanisms

In this study, the feasibility and mechanism of Pb2+ and malachite green (MG) adsorption from wastewater using KMnO4-modified bamboo biochar (KBC) was evaluated. The KBC was characterized by SEM–EDS, XRD, FTIR and XPS. The adsorption results for Pb2+ conformed to pseudo-second-order kinetics and the Langmuir model theory. Unlike the case for Pb2+, the Freundlich model better described the adsorption behaviour of MG, indicating that adsorption occurred within multiple molecular layers. Both pseudo-first-order kinetics and pseudo-second-order kinetics fit the MG adsorption data well, indicating that physical adsorption was involved in the adsorption process. In addition, the maximum adsorption capacity for Pb2+/MG was 123.47/1111.11 mg·g−1, KBC had high adsorption capacities for Pb2+ and MG, and the mechanisms of Pb2+ adsorption were mineral precipitation, functional group complexation, and cation-π interactions, while the main mechanisms for MG adsorption were pore filling, π–π interactions, and functional group complexation. In this study, KMnO4-modified biochar was prepared and used as an efficient adsorbent, and showed good application prospects for treatment of wastewater containing MG and Pb2+.

Engineered nanomaterials for (waste)water treatment - A scientometric assessment and sustainability aspects

Application of nanomaterials for the treatment of effluents originated from various industrial and non-industrial sources, has been rapidly developed in recent decades. In this situation, there is a need for conclusive studies to identify the current status of the knowledge in this field and to promote the commercialization of such technologies by providing recommendations for future studies. In the present manuscript, a scientometric assessment on the progress made in this field has been performed and the results have been organized and discussed in terms of science statistics, research hotspots and trends, as well as the relevant sustainability aspects. Based on a set of keywords, identified through a pre-literature analysis, a total of 6539 documents were retrieved from the Web of Science (WoS) database and analyzed to achieve the main goals of this study. The results demonstrate that the studies in this field have been initiated since the beginning of the 2000s but were mainly performed in lab and pilot scales. Also, China and Iran were identified as the most contributing countries in this scientific area in terms of the number of publications. Among various types of engineered nanomaterials (ENMs), there has been especial attention for the application of iron-based nanomaterials as well as carbonaceous structures (such as graphene oxide and biochar). Besides, there are not still strong collaborations formed among researchers in this area worldwide. Regarding the research hotspots, the synthesis of green and sustainable nanomaterials (e.g., biosynthesis approaches) has received attention in recent years. The results can also demonstrate that the most widely studied pathway for the removal of pollutants from (waste)waters involves the adsorption of the pollutants using ENMs. Treatment of contaminants of emerging concern (CECs) as well as exploring the mechanisms involved in the treatment of contaminated (waste)waters using ENMs and the possible by-products are considered the current trends in the literature. Regarding the sustainability aspects of ENMs for (waste)water treatment, the results achieved in this study calls for in-depth sustainability studies, which consider parameters such as economic, environmental, and social aspects of nanomaterials utilization for (waste)water treatment purposes, besides the technical parameters, to push transferring such technologies from lab and pilot scales to large and real-scale applications.