Heavy Metal Adsorption Capacity Research Articles

Porous graphene nanoplatelets encompassed with nitrogen and sulfur group for heavy metal ions removal of adsorption and desorption from single or mixed aqueous solution

Heavy metal contamination is a main common environmental issue in the world and a significant risk to public health. However, the development of environmentally sustainable and technically viable solutions or adsorbents for the treatment of water contamination caused by heavy metals is urgently needed. In this work, an eco-friendly approach of porous oxidized graphene (O-Gr), nitrogen-graphene (N-Gr), sulfur-graphene (S-Gr), and nitrogen, sulfur-graphene nanoplatelets (NS-GrNPs) via dry ball milling method was used to prepared. The as-prepared samples were investigated the physicochemical properties through the variable analytical tools. Furthermore, the NS-GrNPs has shown the exalted heavy metal ions adsorption and desorption of up to 99.706, 94.558, 78.62% for 60 min and 72.62, 56.54, 80.38 %, receptively. NS-GrNPs sample exhibits the enhanced adsorption capacity value was 987.06, 935.58, 776.2 mg/g. Conclusively, NS-GrNPs exhibits effective heavy metal ions and adsorption capacity, and it is low-cost, environmentally friendly, flexible, and suitable for practical application.

Evaluation of Aerogel Spheres Derived from Salix psammophila in Removal of Heavy Metal Ions in Aqueous Solution

Heavy metal wastewater treatment is a huge problem facing human beings, and the application degree of Salix psammophila resources produced by flat stubble is low. Therefore, it is very important to develop high-value products of Salix psammophila resources and apply them in the removal heavy metal from effluent. In this work, we extracted the cellulose from Salix psammophila, and cellulose nanofibers (CNFs) were prepared through TEMPO oxidation/ultrasound. The aerogel spheres derived from Salix psammophila (ASSP) were prepared with the hanging drop method. The experimental results showed that the Cu(II) adsorption capacity of the ASSP composite (267.64 mg/g) doped with TOCNF was significantly higher than that of pure cellulose aerogel spheres (52.75 mg/g). The presence of carboxyl and hydroxyl groups in ASSP enhanced the adsorption capacity of heavy metals. ASSP is an excellent heavy metal adsorbent, and its maximum adsorption values for Cu(II), Mn(II), and Zn(II) were found to be 272.69, 253.25, and 143.00 mg/g, respectively. The abandoned sand shrub resource of SP was used to adsorb heavy metals from effluent, which provides an important reference value for the development of forestry in this sandy area and will have a great application potential in the fields of the adsorption of heavy metals in soil and antibiotics in water.

Upravljanje otpadnom biomasom iz prehrambene industrije - potencijala primena koštica breskve za prečišćavanje otpadnih voda

As available at lowor zero-cost, agricultural and food industry waste biomass has great potential to be used for wastewater treatment. It has been shown that, with minimum of chemical or mechanical pre-treatment, waste biomass has great adsorption capacity for different heavy metals, organic and biological pollutants from both drinking and wastewater. Since biomass is a renewable resource that is generated daily as waste and requires storage, its inclusion in sustainable development and the circular economy would have multiple benefits for society as a whole. The use of waste biomass for wastewater treatment would have a positive environmental, energy and economic impact on a country's welfare, especially developing ones.

Effect of Adsorbents on Resistance Parameters of Heavy Metal-contaminated Clayey Sand Soils

Combining soil with some adsorbents improves soil structure and shear strength. Thus, an optimal ratio of some adsorbents in the soil composition enhances soil adsorption capacity, reduces the possibility of groundwater contamination with these hazardous compounds, and leads to increase soil resistance parameters. This paper investigates the effect of heavy metals and adsorbents on the geotechnical behavior of clayey sand soils contaminated with lead and zinc as heavy metals as well as zeolite and rice husk ash as adsorbents. Clayey sand (mixture of sand with 20% kaolinite or bentonite) was considered as a base composition and the behavior of it was studied in both contaminated and uncontaminated states. Then, for increasing the heavy metal adsorption capacity of clayey sand, two types of adsorbents (zeolite and rice husk ash ) were added to the base composition and their behavior were investigated in the case of Lead and Zinc contamination. The results revealed that replacing the rice husk ash and zeolite adsorbents in the sand combination with 20% kaolinite clay significantly reduced the concentration of lead and zinc nitrate in the solution. Replacing 15% of rice husk ash with kaolinite heightened the absorption of lead nitrate and zinc nitrate by 228.8% and 291.6% in kaolinite sand. It was also found that adding nitrate to kaolinite increased the liquid and plastic limits. According to the results, in kaolinite, the value of the liquid limit rose from 49.8 to 59.1 upon elevating the concentration of lead to 5000 ppm, while the plastic limit also increased from 31 in the non-contaminated state to 36.4 in 5000 ppm in the infected state. According to obtained results, the dispersed structure is formed by increasing the concentration of lead nitrate in composition of sandy clay with low plasticity adsorbent; thus, shear resistance decreased. Changing in type of clay minerals to high plasticity cause the different trend in shear resistance parameters. Increasing the concentration of lead nitrate in bentonite composition, lead to flocculated structure be formed and shear strength increased.

Drought Resistance and Heavy Metal Adsorption Capacity of Mulberry in Alpine Regions

Mulberry is an important perennial economic crop. It is the pursuit of modern mulberry breeders to continuously improve the drought resistance and heavy metal adsorption capacity of mulberry varieties. In this paper, three excellent mulberry varieties were introduced and cultivated in the alpine region, and the drought resistance of mulberry seedlings under different drought degrees and different days of drought was analysed. The root powder of mulberry seedlings was ground and dissolved by combining physical and chemical methods. The heavy metal ions are taken as an example. The heavy metal adsorption capacity of the root powder of mulberry seedlings under different initial ion concentrations and different pH values is analysed. The experimental results show that the drought resistance of different varieties is different. The concentration of heavy metal ions and pH value can only be achieved.

Speciation and release risk of heavy metals bonded on simulated naturally-aged microplastics prepared from artificially broken macroplastics

The negative impact of microplastics (MPs) act as metals vectors to environment and ecosystem have been paid more and more attention, and the accumulation risk of them to human body through the food chains and food webs needs to attract attention. In addition, the MPs bonded with heavy metals transport from river into the sea with high salinity may also have metals release risk. Herein, natural aged microplastics prepared from artificially broken macroplastics adsorbed with heavy metals accumulated from the natural environment were tested for their states and release risk in several simulated solution (NaCl and gastrointestinal solutions) to understand their effects on environment and human health. The adsorption capacity of different heavy metals on MPs was different during natural aging process proved by four-acid digestion method. Metals with high accumulation (including Pb, As, Cr, Mn, Ni, Zn, Co, Cu and Cd) on NAMPs were selected for further study. Results obtained via three-step extraction method showed that these heavy metals were mainly present as acid-extractable and reducible ions, which were characterized by high bioavailability. Release experiments suggested the notable Mn, Zn, As, Cr, Cu and Ni release in NaCl solution, and significant release of Mn, Zn, As, Cr, Cu, Pb and Ni in gastrointestinal solutions. The high metal release ratio in the simulated gastric solution was attributed to the weak binding of metal ions to NAMPs in acidic environment. This study will play a vital rule in assessing the ecological risks associated with MPs in natural environment.

Pre-grafting effect on improving adsorption efficiency of cellulose based biosorbent for Hg (II) removal from aqueous solution

Pre-grafting technique with excellent biocompatibility is introduced to cellulose based adsorbent material which greatly enhances the adsorption properties like adsorption capacity, equilibrium time and regeneration performance. • Pre-grafting technique greatly enhances the adsorption performance of adsorbent. • Adsorption capacity is retained more than 85% after five cycles of regeneration. • Pre-grafting technique based on cellulose has excellent biocompatibility. Adsorption technique is considered to be an effective way to remove heavy metal species from aqueous solutions and cellulose based materials are widely used as good candidates of adsorbents. However, low grafting efficiency of functional groups has been a major challenge reducing the heavy metal adsorption capacity of cellulose based adsorbents. In this work, a diethylenetriaminepentaacetic acid modified cellulose is synthesized by an efficient catalyzed approach on the basis of glycidyl methacrylate pre-grafting (G-DMC). As a contrast, epichlorohydrin is employed as coupling side chain to react with the same polyacid (DMC) to evaluate the effect of pre-grafting. It is verified that “pre-grafting technique” significantly improves the load efficiency of polyacid and enhances the adsorption performance that the as-prepared adsorbent using pre-grafting technique shows much higher adsorption capacity ( Q m ) towards mercury in aqueous solutions with Q m of 443.8 mg/g, which is 3.5 folds of the epichlorohydrin grafted one. In addition, the kinetic adsorption experiments confirm that G-DMC achieves its adsorption equilibrium in a shorter time of 10 min. After five cycles of regeneration process, G-DMC could maintain 88.13% of its original adsorption capacity. Moreover, the live/dead cell fluorescence staining demonstrates the good biological safety of the material that the cell viability of murine L929 fibroblasts could retain close to 100% after 24 h of cultivation with G-DMC. Thus, this pre-grafting strategy is expected to provide an environmentally friendly method to amplify the adsorption capacity of the designed receptor for guest species.

Magnetization Improved Fine Particle Biochar Adsorption of Lead

ABSTRACT Biochar can be an alternative sorbent to the high cost activated carbon for wastewater treatment. Its adsorption capacity for heavy metals can be increased by magnetizing it with iron. In this study, we compared the physiochemical properties and sorption capacity of an iron-coated fine empty fruit bunch biochar (IC-EFBB) for Pb with a commercially available activated carbon (AC) and the uncoated fine empty fruit bunch biochar (EFBB). The results revealed that the AC had greater micropores surface area (671.14 m2 g−1), compared to the IC-EFBB (25.79 m2 g−1) and EFBB (2.57 m2 g−1). On the other hand, the IC-EFBB had the highest pH, and content of functional groups (OH and CO) while the EFBB had the highest total oxygen containing functional groups, CEC, and the lowest PZC. The sorption data of Pb by EFBB, IC-EFBB and AC were better fitted to the Langmuir adsorption as indicated by the R2 (1.00, 1.00 and 0.98, respectively) and RMSE values (0.009, 0.017 and 0.428, respectively). The IC-EFBB (142.86 mg g−1) had the highest adsorption capacity for Pb followed by EFBB (103.09 mg g−1) and the lowest was AC (50.51 mg g−1). The results indicated that surface area was not an important indicator for Pb sorption by the adsorbents but the amount of oxygen-containing functional groups, pH and CEC were the dominant factors. The IC-EFBB was readily separated from the aqueous solution using an external magnetic force. Therefore, it can be concluded that the IC-EFBB can be a very good alternative sorbent to remove heavy metals from wastewater.

A study on activation mechanism in perspective of lignin structures and applicability of lignin-derived activated carbons for pollutant absorbent and supercapacitor electrode

In this study activated carbons were produced from the biorefinery waste lignin (Asian lignin (AL) USA & Inbicon lignin (IL) Denmark) to evaluate their potential in waste water treatment and as energy storage devices. These products were studied for their surface characteristics as a function of reaction temperature, time, and catalyst loading accordingly. Under the conditions with a temperature lower than 750 °C and within a reaction time of 1 h, the catalytic reaction of alkali-carbon bonding occurred from the external surface, and a turbostratic disorder structure with a large aromatic ring system was formed. More severe reaction conditions accelerated the volatile release of de-alkylated aromatics such as benzene and naphthalene, along with structure and surface collapse. The maximum BET surface area of 2782 m2/g was obtained at 750 °C, 2 h and catalyst ratio of 4. Lignin-derived activated carbon was more efficient for the removal of organic pollutants (<50% adsorption capacity) rather than heavy metals (adsorption capacity >90%) due to interaction of π-π bonding. Furthermore, the activated carbon has a potential to be used as a supercapacitor electrode with high specific capacitance (214.0 F/g AL lignin) and an excellent cyclic stability (95% of their initial capacity). The results of this study demonstrate that lignin is an attractive precursor to produce activated carbons with diverse applications both as biosorbent and as a carbon electrode material even so with acceptable performance.

Changes of High-Purity Insoluble Fiber from Soybean Dregs (Okara) after Being Fermented by Colonic Flora and Its Adsorption Capacity.

In order to explore the changes and properties of high-purity insoluble dietary fiber from okara (HPIDF) after entering the colon and be fermented by colonic flora, fermented high-purity insoluble dietary fiber (F-HPIDF) was obtained by simulated fermentation in vitro by HPIDF and colonic flora from C57BL/6 mice. For exploring the differences of HPIDF and F-HPIDF, the changes of structure (SEM. FTIR, XRD, particle size, specific surface area, monosaccharide composition) and adsorption properties (water, oil, heavy metal irons, harmful substances) of HPIDF/F-HPIDF were explored. The results showed that F-HPIDF had a higher water-holding capacity (19.17 g/g), water-swelling capacity (24.83 mL/g), heavy metals-adsorption capacity (Cd2+: 1.82 μmol/g; Pb2+: 1.91 μmol/g; Zn2+: 1.30 μmol/g; Cu2+: 0.68 μmol/g), and harmful substances-adsorption capacity (GAC: 0.23 g/g; CAC: 14.80 mg/g; SCAC: 0.49 g/g) than HPIDF due to the changes of structure caused by fermentation. In addition, with the fermentation of HPIDF, some beneficial substances were produced, which might be potential intestinal prebiotics. The study of F-HPIDF strengthens the speculation that HPIDF may have potential bioactivities after entering the colon, which proved that okara-HPIDF may have potential functionality.

Predicting Heavy Metal Adsorption on Soil with Machine Learning and Mapping Global Distribution of Soil Adsorption Capacities.

Studying heavy metal adsorption on soil is important for understanding the fate of heavy metals and properly assessing the related environmental risks. Existing experimental methods and traditional models for quantifying adsorption, however, are time-consuming and ineffective. In this study, we developed machine learning models for the soil adsorption of six heavy metals (Cd(II), Cr(VI), Cu(II), Pb(II), Ni(II), and Zn(II)) using 4420 data points (1105 soils) extracted from 150 journal articles. After a comprehensive comparison, our results showed that the gradient boosting decision tree had the best performance for a combined model based on all the data. The Shapley additive explanation method was used to identify the feature importance and the effects of these features on the adsorption, based on which six independent models were developed for the six metals to achieve better model performance than the combined model. Using these independent models, the global distribution of heavy metal adsorption capacities on soils was predicted with known soil properties. Reversed models, including one combined model for all the six metals and six independent models, were also built using the same data sets to predict the heavy metal concentration in water when the adsorbed amount is known for a soil/sediment.

Heavy metal enrichment in drinking water pipe scales and speciation change with water parameters

Pipe scales that form in drinking water distribution systems (DWDS) can accumulate pollutants that may be re-released into bulk water, posing a significant threat to water safety. This study aims to evaluate the pollutant enrichment capacity of the pipe scale and identify speciation changes in heavy metals under variations in water quality. When the water quality conditions changed, the forms of inorganic metal elements in drinking water pipe scales also changed and the proportion of unstable forms increased, thereby increasing the risk of secondary pollution. Morphological analysis showed that the pipe scale samples had porous structures and large specific surface areas (the maximum was 52.94 m2/g, which is higher than that of many natural adsorbents), which could promote the accumulation of contaminants. XRD profiles also showed that the pipe scale samples were rich in substances with heavy metal adsorption capacities, such as Fe3O4. As the pH changed from 6 to 10, no significant difference in the release of heavy metals was found. The maximum release of Cu, Cr, As, Pb, and Cd at pH 8 was 0.56, 0.51, 1.82, 0.84, and 0.72 μg/g, respectively. Although the amounts were small, the speciation distribution of the heavy metals changed significantly. In addition, the proportion of unstable fractions increased, which increased the release risk of the pipe scale. The presence of humic acid accelerated the dissolution of organic matter and metals in the pipe scale, which further proved that the pipe scales were unstable and susceptible to water quality conditions. The pipe scales could not maintain stability when the water quality changed, and the DWDS should be regularly monitored and cleaned when necessary.

Simultaneous adsorption and degradation tetracycline and heavy metals using polyaniline/chitosan to loading nanoscale zero-valent iron

ABSTRACT In this study, the nanoscale zero-valent iron/polyaniline/chitosan (nZVI/PANI/CS) composite was prepared and was used to remove tetracycline (TC) and heavy metal (Ni(II)) from the wastewater. The dispersity of composite was observed to be significantly improved. The performance of nZVI/PANI/CS composite was investigated and the removal efficiency for tetracycline and heavy metals was 98.8% and 99.0%, respectively. The removal process of TC and Ni(II) can better describe by Langmuir model and the pseudo-second-order kinetic model. And the maximum adsorption capacities of tetracycline and heavy metals are 141.84 mg/g and 165.34 mg/g. Further, the mechanism analysis shows that TC was degraded into hypotoxic or non-toxic small molecules by nZVI/PANI/CS and the most of Ni(II) was transformed into Ni0 by reducing effect. Besides, the stability and reusability experimental was implemented, indicating the performance of nZVI was improved after adding PANI and CS.

The fuel properties and adsorption capacities of torrefied camellia shell obtained via different steam-torrefaction reactors

In this paper, three different steam-torrefaction reactors were employed to adjust the pyrolysis performance and adsorption capacities of biochar obtained from camellia shell (CS). The fuel performance of biochar was evaluated by heat value and component analysis. Meanwhile, the pyrolysis characteristics, mechanism of biochar and pyrolysis kinetics were investigated using thermogravimetric analysis (TGA), two-dimensional perturbation-based correlation infrared spectroscopy (2D-PCIS) analysis. The results showed that torrefied biochar obtained from atmospheric steam-torrefaction had the highest solid yield (88.4%), energy retention efficiency (ERE) (94.9%), methylene blue (99.63 mg/g) and heavy metals adsorption capacity which had exceeded that of commercial activated carbon. The pyrolysis kinetics results showed that the activation energy of hemicellulose significantly decreased with the increase of steam saturation. 2D-PCIS analysis indicated that the formation of pseudo-lignin was promoted with the torrefaction temperature based on the increased intensity of CC in aromatic skeleton. The element analysis and solid yield of biochar showed that the role of steam saturation was equal to the temperature on the torrefaction performance.

Nickel (Ni2+) Removal from Water Using Gellan Gum–Sand Mixture as a Filter Material

Microbial biopolymers have been introduced as materials for soil treatment and ground improvement purposes because of their ability to enhance soil strength enhancement and to reduce hydraulic conductivity. Several studies in the field of environmental engineering have reported heavy metal adsorption and removal from contaminated water using common biopolymers. In particular, gellan gum biopolymers have drawn significant attention for use in metal ion adsorption. This study aims to investigate the heavy metal adsorption capacity of a gellan gum biopolymer–sand mixture when nickel-contaminated water is pumped upward through a uniform gellan gum–sand mixture column. The main aims of this study are (1) to clarify the Ni2+ adsorption phenomenon of gellan gum-treated sand, (2) to assess the Ni2+ adsorbability of gellan gum–sand mixtures with different gellan gum content, and (3) to examine the gellan gum–sand filter thickness and flow rate effects on Ni2+ adsorption. The results of this experiment demonstrate the effectiveness of gellan gum in terms of Ni2+ adsorption and water flow rate control, which are essential criteria of a filter material for contaminated water treatment.

Comment on “Hazardous microplastic characteristics and its role as a vector of heavy metal in groundwater and surface water of coastal south India”

Researchers interested in a paper’s statement or aiming to acquire useful information from scientific papers rely heavily on references. Additionally, calculation accuracy is important for ensuring the technical soundness of scientific papers. However, inaccurate citations and calculations are common in scientific literature. A recently published paper in the Journal of Hazardous Materials reported a study on microplastics in groundwater and surface water from coastal south India (Tamil Nadu state) and the heavy metal adsorption capacities of different polymers. In this study, we identified critical calculation errors and incorrect reference citations.

Heavy Metal Adsorption and Release on Polystyrene Particles at Various Salinities

Microplastics (MPs) and heavy metals are two major types of pollutants that interact with each other, but they are poorly understood. Polystyrene (PS) is one type of MPs that is often detected in aquatic environments. In this study, we examined the adsorption capacity and release rate of heavy metals with respect to different particle sizes of PS, heavy metals, initial heavy metal concentrations, and salinities. Virgin (new) PS with diameters of 20, 50, 130, and 250 μm was used in this study, and four heavy metals (lead, cadmium, copper, and zinc) were used. The results showed that larger PS particle sizes adsorbed more heavy metals even though it took longer to achieve equilibrium adsorption. An increase in heavy metal concentration caused the adsorption capacity (μg g–1) of PS particles to also increase, but the adsorption rate (%) decreased. Increased salinity of the heavy metal solution resulted in a slower adsorption time and a lower adsorption capacity and release rate from the surface of PS particles. Different heavy metals also had different adsorption capacities. Pb was consistently more highly adsorbed by MPs, followed by Cu, Zn, and Cd. Larger PS sizes released heavy metals faster than smaller PS sizes, and the amounts of heavy metals released were higher. The heavy metal with the highest release rate was Cd, followed by Pb, Cu, and Zn. Finally, our findings highlight the interactions between PS and heavy metals and strongly support that PS particles can act as vectors for heavy metals in aquatic systems.

Microplastics aged in various environmental media exhibited strong sorption to heavy metals in seawater

To date, the degradation of microplastics (MPs; <5 mm) in different environments, particularly their adsorption characteristics for coexisted metal pollutants remains to be elucidated. Thus, this study investigated the effects of aging MPs, including polyamide (mPA), polyethylene terephthalate (mPET), polystyrene (mPS), and polyvinyl chloride (mPVC) for 3 months under UVA irradiation in four environmental media (air, seawater, sand, and soil) and adsorption of heavy metals (Cu, Cd) onto seawater-aged mPS and mPVC. The results showed that surface morphological changes, including cracks, oxidized particles, and wrinkles, appeared on aged MPs. The heavy metal adsorption capacity decreased in the order aged mPVC > aged mPS > unaged mPS > unaged mPVC, and the Cu2+ and Cd2+ ions competed for active adsorption sites on the MPs surfaces. Overall, the aging environment affected the physical and chemical properties of MPs and the aging of MPs enhanced their adsorption of coexisting metals tested.

Polydopamine-Based Surface Modification of Chlorella Microspheres for Multiple Environmental Applications.

Towards addressing water pollution issues, the development of multifunctional chlorella with applications ranging from sensing pollutants to heavy metal and oil removal is described. The use of chlorella cells, which are widely abundant natural structures, leads to simple and low-cost mass production of effective functional materials. Bioinspired surface modification approaches mediated by polydopamine can endow chlorella with enhanced adsorption capacity for heavy metals, as well as superhydrophobic, fluorescence and magnetic properties according to the desired application. The resulting chlorella exhibits excellent heavy metal and oil removal ability, while magnetic propulsion and guidance allow directional motion over long distances for implementation in situ removal. Moreover, it is further demonstrated that chlorella can be used as a biosensor to detect metal ions by taking advantage of the fluorescence properties of carbon dots. Such use of chlorella provides a new way for the large-scale production of functional materials to tackle water pollution.

Amide-functionalized graphene-assembled monoliths with high adsorption capacity of Cd2+

Three-dimensional graphene-assembled monoliths (GAs) are emerging materials used in supercapacitors, catalysis, etc. However, GAs prepared by mainstream reduction methods (reduced GAs, RGAs) have fewer functional groups and display poor adsorption capacity of heavy metals. In this paper, we developed a new method of preparing amide-functionalized GAs (AGAs) with high degree of modification by the reaction of carboxyl-functionalized graphene oxides and ethylenediamine. AGAs contained multiple functional groups and exhibited dendritic structure at micron scale. Benefiting from these properties, the maximum adsorption capacities Cd 2 + on AGAs at T = 303 K were about 56.6 mg/g, which was twice that of RGAs and higher than that of graphene ( ∼ 10 mg/g) and biochar ( ∼ 18 mg/g) at the same conditions. By calculating the Gibbs free energies ( Δ G), the adsorption of Cd 2 + on AGAs was proved a spontaneous process, while the adsorption of Cd 2 + on RGAs was not spontaneous X-ray photoelectron spectroscopy analysis demonstrated that AGAs contained more adsorption sites and Cd 2 + adsorbed on AGAs through coordination bond. Thus, AGAs exhibited good application potentials as adsorbents for the removal of Cd 2 + from contaminated water. • GAs with rich functional groups were successfully prepared. • The three-dimensional structure was constructed by forming amide groups. • Compared with RGAs, AGAs had more potential adsorption sites for heavy metals. • Compared with RGAs, AGAs had higher adsorption capacity for Cd 2+ at 30 °C. • The improved synthesis method makes the adsorption of Cd 2+ by AGAs spontaneous.