Metal Concentration In Solution Research Articles

Experimental study on adsorption properties of functional magnetic nanomaterials for heavy metal pollutants

In order to effectively remove heavy metal pollutants and improve the quality of the ecological environment, the experimental study on adsorption properties of functional magnetic nanomaterials for heavy metal pollutants was studied. Magnetic nano-Fe3O4 materials were prepared by hydrothermal method. Fe3O4, Fe3O4@SiO2 and 3NH2-Fe3O4@SiO2 magnetic nanomaterials were obtained by functional modification. The adsorption properties of functionalised magnetic nanomaterials for Cd(II) and Pb(II) in water were analysed by batch test. The results show that 3NH2-Fe3O4@SiO2 has the highest adsorption capacity for Cd(II) and Pb(II); with decreasing temperature, the order of adsorption capacity for Pb(II) is Fe3O4 > Fe3O4@SiO2 > 3NH2-Fe3O4@SiO2. The Langmuir adsorption isotherm model can better fit the adsorption process of functionalised magnetic nanomaterials to Cd(II) and Pb(II) solutions. In different initial heavy metal solution concentration systems, the materials can promote the adsorption of Cd(II) and Pb(II) adsorption.

GROWTH EVALUATION OF CUCUMIS SATIVUS L. (CUCUMBER PLANT) IN ARSENIC AND CHROMIUM TREATED SOILS

Evaluation of the growth of Cucumis sativus in arsenic (As) and chromium (Cr) treatedsoils was carried out. Parameters measured were germination, plant height, number ofleaves, relative water content and total chlorophyll. The concentrations of metalsolutions applied were 0, 30, 60, 120 and 240 ppm of arsenic and chromium saltsseparately. The study was conducted as potted field experiment. The treatments werereplicated four times. Three days after planting (DAP), C. sativus seeds germinated inall soil treatments. The highest percentage germination was obtained in controltreatments 15 DAP. The metal treatments depressed germination. Similarly, plantheight was depressed significantly by As and Cr treatments (?=0.05). Plant heightvalues recorded for 240 ppm As and 240 ppm Cr were 24.1% and 36.5% of theirrespective values for control. Differences in number of leaves produced per plants werefound to be statistically significant under arsenic treatment only. The values obtained forrelative water content and total chlorophyll showed that plants grown in As and Crtreated soils were inhibited. Generally, plants grown under control conditions gavehigher values. From the growth parameters evaluated, arsenic treatments was moretoxic to Cucumis sativus than chromium treatments.

Isotherm, Kinetic, and Selectivity Studies for the Removal of 133Ba and 137Cs from Aqueous Solution Using Turkish Perlite.

The efficiency of 133Ba and  137Cs removal from aqueous solution is vital to mitigate ecological concerns over spreading these radionuclides in the environment. The present work focused on the use of Turkish perlite for the sorptive removal of  133Ba and  137Cs from aqueous solution by the radioindicator method. Perlite was characterized by XRF, XRD, FTIR, SEM-EDX, and BET analyses. The maximum percentage removals of 88.2% and 78.7% were obtained for  133Ba and  137Cs at pH 6 and pH 9, respectively. For both ions, the sorption equilibrium was attained relatively rapidly. Experimental kinetic data were well described with pseudo-second-order and intraparticle diffusion models. The uptake of both ions increased with the increase in metal concentration (1 × 10-5 to 5 × 10-2 mol/L) in solution. The maximum uptake capacities of  133Ba and  137Cs were found to be 1.96 and 2.11 mmol/g, respectively. The effect of competing ions decreased in the order of Ca2+>K+>Ni2+>Na+ for  133Ba sorption, whereas for  137Cs sorption, the order was determined as Ca2+>Ni2+>K+>Na+. Selectivity studies pointed out that sorption of  133Ba onto perlite is preferable to  137Cs. Therefore, Turkish perlite is a promising, cost-effective, and efficient natural material for the removal of  133Ba and  137Cs from relatively diluted aqueous solution.

Study on leaching characteristics of MSWIFA in different pH environment

The change of leaching solution of waste incineration fly ash (MSWIFA) after shaking under different initial extractant pH was studied, and the change trend was compared with that of fly ash under different extractant concentrations. In addition, the leaching characteristics of heavy metals were analyzed under the two methods. The results showed that the pH change of the initial extractant can not truly simulate the environment of fly ash landfill, and the former can not reflect the pH of the final leaching solution. Changing the initial extractant concentration within a certain range can gradually change the final leaching solution from alkaline to acidic, which can truly reflect the environmental changes experienced by fly ash in the landfill (such as rainstorm scouring, drought and other environment). The leaching concentration of heavy metals in the leaching solution obtained by shaking fly ash under different acetic acid concentrations reflects the actual leaching characteristics of heavy metals under different pH conditions, in which Pb and Zn are amphoteric leaching, and the other metals are cationic leaching.

Study on leaching characteristics of MSWIFA in different pH environment

The change of leaching solution of waste incineration fly ash (MSWIFA) after shaking under different initial extractant pH was studied, and the change trend was compared with that of fly ash under different extractant concentrations. In addition, the leaching characteristics of heavy metals were analyzed under the two methods. The results showed that the pH change of the initial extractant can not truly simulate the environment of fly ash landfill, and the former can not reflect the pH of the final leaching solution. Changing the initial extractant concentration within a certain range can gradually change the final leaching solution from alkaline to acidic, which can truly reflect the environmental changes experienced by fly ash in the landfill (such as rainstorm scouring, drought and other environment). The leaching concentration of heavy metals in the leaching solution obtained by shaking fly ash under different acetic acid concentrations reflects the actual leaching characteristics of heavy metals under different pH conditions, in which Pb and Zn are amphoteric leaching, and the other metals are cationic leaching.

Immobilization of exopolymeric substances from bacteria for metal removal: A study on characterization, optimization, reusability and toxicity

This study investigated the immobilization of exopolymeric substances (EPS) from Bacillus cereus using sodium alginate to form EPS beads for metal removal. The EPS beads were characterized and their optimum biosorption conditions established (biosorbent dosage, initial metal concentration and pH of metal solutions). The EPS beads were also tested for reusability by using them continuously for five metal removal cycles with desorption process in between cycles. The toxicity of the treated metal solutions was tested by phytotoxicity tests. Results revealed that EPS beads demonstrated significantly higher metal removal efficiency (Pb: 99.26%, Cr: 50.73%, Cu: 48.94%, Zn: 29.81%, Cd: 20.29%) compared to plain alginate beads (without EPS) (Pb: 84.45%, Cu: 31%, Cr: 28.37%, Zn: 11.91%, Cd: 9.37%). SEM-EDX analysis detected Cu, Pb, Zn, Cd and Cr on the surface of EPS beads. Optimum conditions for Pb removal by EPS beads were from the use of 0.1 g of biosorbent at 100 mg/L initial metal concentration and pH 5. By contrast, Cu, Zn, Cd and Cr were optimally removed by 0.3 g of biosorbent at 25 mg/L initial metal concentration and pH 5. EPS beads can be reused up to five times while maintaining a high rate of metal removal efficiency (Pb- 99.52%, Cr- 89.23%, Cu- 89.17%, Zn-52.52%, Cd-39.12%). This was achieved through desorption with nitric acid that consistently recovered 76–93% of the metal adsorbed. FTIR analysis reveals that nitric acid is capable of restoring the functional groups present within EPS beads, allowing it to bind with metal ions in repeated cycles. Metal solutions treated with EPS beads were less toxic as seedling shoots (pre-treated: 0–10 cm, post-treated: 1.2–18.1 cm) and roots (pre-treated: 0–7.8 cm, post-treated: 0.8–15.1 cm) grew well, which suggested that reduced levels of metals led to reduced phytotoxicity. This study provides an insight into the use of EPS beads for metal removal, highlighting the benefits and reusability of the beads for future wastewater treatment.

Sulfur and oxygen isotope constraints on sulfate sources and neutral rock drainage-related processes at a South African colliery

Understanding the fundamental controls that govern the generation of mine drainage is essential for waste management strategies. Combining the isotopic composition of water (H and O) and dissolved sulfate (S and O) with hydrogeochemical measurements of surface and groundwater, microbial analysis, composition of sediments and precipitates, and geochemical modeling results in this study we discussed the processes that control mine water chemistry and identified the potential source(s) and possible mechanisms governing sulfate formation and transformation around a South African colliery. Compared to various South African water standards, water samples collected from the surroundings of a coal waste disposal facility had elevated Fe2+ (0.9 to 56.9 mg L−1), Ca (33.0 to 527.0 mg L−1), Mg (6.2 to 457.0 mg L−1), Mn (0.1 to 8.6 mg L−1) and SO4 (19.7 to 3440.8 mg L−1) and circumneutral pH. The pH conditions are mainly controlled by the release of H+ from pyrite oxidation and the subsequent dissolution of carbonates and aluminosilicate minerals. The phases predicted to precipitate by equilibrium calculation were green rusts, ferrihydrite, gypsum, ±epsomite. Low concentrations of deleterious metals in solution are due to their low abundance in the local host rocks, and their attenuation through adsorption onto secondary Fe precipitates and co-precipitation at the elevated pH values. The δ34S values of sulfate are enriched (−6.5 ‰ to +5.6 ‰) compared to that of pyrite sampled from the mine (mean −22.5 ‰) and overlap with that of the organic sulfur of coal from the region (−2.5 to +4.9 ‰). The presence of both sulfur reducing and oxidizing bacteria were detected in the collected sediment samples. Combined, the data are consistent with the dissolved sulfate in the sampled waters from the colliery being derived primarily from pyrite probably with the subordinate contribution of organic sulfur, followed by its partial removal through precipitation and microbially-induced reduction.

Removal Efficiency, Accumulation and Biochemical Response of Lemna minor L. Exposed to Some Heavy Metals

Both terrestrial and aquatic plants can be used for removing various pollutants such as hydrocarbons, heavy metals, etc via phytotechnology. This study applied different concentrations of Cd, Pb, and Cr (1, 4, and 8) mg/L to evaluate heavy metal removal and toxicological effects on Lemna minor L. in laboratory experiments for 12 days. At the beginning and the end of experiments, the parameters were measured, including fresh weight, relative growth rate (RGR), total chlorophyll, protein, and proline content, as well as other parameters measuring at the end of experiments such as metal remaining in water, removal efficiency, and bioconcentration factor(BCF) in plant. The results demonstrated a decrease in metal concentrations in aqueous solution at all treatments with different values. The highest removal efficiencies were Pb >Cr >Cd, respectively. It was 88.8 % at the 1 mg/L of lead and 22.22 % at 8 mg/L of Cd. The toxicological effects on plants as a response to selected metals were increased with increasing concentrations and periods of exposure. The reduction in fresh, dry weight, t. chlorophyll, and protein content were more in Cd>Cr>Pb respectively compared with increased in control treatments. The highest reduction at 8 mg/L of Cd were 0.329 µg/gram, 18.656 % for total chlorophyll and protein content respectively. The result showed the proline content increased with increasing concentration and the value was highest in Cd>Cr>Pb. The results suggest that Lemna minor L. is a good candidate for treating polluted water with heavy metals.

Combining a Standardized Batch Test with the Biotic Ligand Model to Predict Copper and Zinc Ecotoxicity in Soils.

Extraction of soil samples with dilute CaCl2 solution in a routinely performed batch test has potential to be used in site‐specific assessment of ecotoxicological risks at metal‐contaminated sites. Soil extracts could potentially give a measure of the concentration of bioavailable metals in the soil solution, thereby including effects of soil properties and contaminant “aging.” We explored the possibility of using a 0.001 M CaCl2 batch test combined with biotic ligand models (BLMs) for assessment of ecotoxicity in soils. Concentrations of Cu2+ and Zn2+ in soil extracts were linked to responses in ecotoxicity tests (microbial processes, plants, and invertebrates) previously performed on metal‐spiked soils. The batch test data for soils were obtained by spiking archived soil materials using the same protocol as in the original studies. Effective concentration values based on free metal concentrations in soil extracts were related to pH by linear regressions. Finally, field‐contaminated soils were used to validate model performance. Our results indicate a strong pH‐dependent toxicity of the free metal ions in the soil extracts, with R 2 values ranging from 0.54 to 0.93 (median 0.84), among tests and metals. Using pH‐adjusted Cu2+ and Zn2+ concentrations in soil extracts, the toxic responses in spiked soils and field‐contaminated soils were similar, indicating a potential for the calibrated models to assess toxic effects in field‐contaminated soils, accounting for differences in soil properties and effects of contaminant “aging.” Consequently, evaluation of a standardized 0.001 M CaCl2 batch test with a simplified BLM can provide the basis for an easy‐to‐use tool for site‐specific risk assessment of metal toxicity to soil organisms. Environ Toxicol Chem 2022;41:1540–1554. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Elimination of Chromium (VI) and Nickel (II) Ions in a Packed Column Using Oil Palm Bagasse and Yam Peels

The single-component adsorption of chromium (VI) and nickel (II) on oil palm bagasse (OPB) and yam peels (YP) in a packed bed column was explored and improved using a central 22-star T composite design. The temperature, bed height, and particle size were evaluated, and the optimized response variable was the removal efficiency. The remaining concentration of heavy metals in solution was determined by Ultraviolet–Visible and Atomic Absorption Spectroscopy. It was found that bioadsorbents have a porous structure, with the presence of functional groups such as hydroxyl, carboxyl, and amino, which favor adsorption processes, and that the adsorption mechanisms controlling the process is cation exchange, precipitation, and complexation on the exposed surface of the biomaterials. In the adsorption trials, removal percentages higher than 87% were obtained in all cases, showing better results in the removal of Cr(VI), and that particle size is the most influential factor. Maximum Cr(VI) capacities of 111.45 mg g−1 and 50.12 mg g−1 were achieved on OPB and YP, respectively, while for nickel values of 103.49 mg g−1 and 30.04 mg g−1 were obtained. From the adjustment of the breakthrough curve to the models, it was determined that the model best able to adjust the data was the Thomas model, and the thermodynamic parameters of Cr(VI) and Ni(II) removal suggest that the process on YP is endothermic, while on OPB it is exothermic. In both biomaterials, the process is controlled by spontaneous chemisorption with a great affinity of the active centers for the ions.

Passive Phyto-Remediation of Heavy Metals by Biosorption of Sargassum cinereum

The industrial effluents with a high amount of pollutant, including heavy metals have adverse effects on the aquatic environment. Different costly conventional treatment technologies are applying for removal of heavy metals from the marine environment. The conventional treatment technologies produce a huge load of toxic chemical sludge on the environment. There is a need of detoxification of environment applying any biological method. So, remediation of heavy metals by marine macro algae is a novel eco-friendly alternative approach. The brown seaweed Sargassum cinereum were used as bio-absorber for heavy metals. To test the biosorption capacity of this brown seaweed, the artificial set up of heavy metal polluted environment were made within the beakers by keeping various concentration of heavy metal solution, and within that concentrated solution, Sargassum cinereum were emerged as per required amount. An optimized and validated Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) has been applied to analyse elements, including, trace metals (Fe, Pb, Cr, As and Ag). The brown seaweed Sargassum cinereum used as bio-absorber for heavy metals. The artificial set up of heavy metal polluted environment were made within beaker by keeping various concentration of heavy metal solution, then Sargassum cinereum were used as per required amount. The iron concentration was 3520.35ppb in normal fresh Sargassum cinereum but Sargassum cinereum which was treated with various concentration of iron solution, showed very high concentration of iron. After 48 hours of treatment with 0.25mM iron solution Sargassum cinereum absorbed 6679.70ppb iron from the solution and treated with high concentration of iron solution such as 4mM absorbed maximum iron such as 21781.3089ppb. Similarly, Sargassum cinereum also have capacity of bio-sorption of Pb, Hg. The metal bio-absorption of Sargassum cinereum remarked for its metal storage capacity. It has been concluded that Sargassum cinereum absorb high amount of Fe, Pb and Hg from solution, so Sargassum cinereum may be use for heavy metal bio-absorption as phyco-cleaner of heavy metals from heavy metal polluted environment. In future, this brown seaweed may be used for cleaning of polluted environment cost effectively

Removal of heavy metals from aqueous media by sunflower husk: A comparative study of biosorption efficiency by using ICP-OES and LIBS

Presented research aimed to develop an alternative approach for the estimation of biosorption capability of sunflower husk. The acid-pretreated sunflower biomass was characterized by scanning electron microscopy combined with energy dispersive X-Ray spectroscopy (SEM-EDX) analysis and Fourier transform infrared (FTIR) spectroscopy. Biosorption efficiency has been evaluated using inductively coupled plasma optical emission spectroscopy (ICP-OES) and laser-induced breakdown spectroscopy (LIBS). The adsorption capacity of the adsorbent was determined as the function of the pH of the solution, the initial concentration of heavy metal solutions, and contact time. The optimal conditions were achieved after 15 min of contact at pH 6, while the percentage of the removal was from 80.0?98.7 %, depending on the element. The results obtained from the kinetic and isotherm studies show that maximum adsorption of ions was quickly reached and followed the pseudo-second-order kinetic model. Real samples were tested and obtained Ni values by LIBS method were 3100?200 and 1240?100 mg kg-1, while estimated values by the ICP-OES were 2995?20 and 1130?10 mg kg-1, respectively. The obtained results prove that LIBS method can be used as a ?green alternative? for the evaluation of biosorption efficiency.

The effect of high-molecular compounds nature on the electroflotation removal of the metal compounds from electrolyte solutions

• Removal of heavy metal ions (Fe (III), Ni (II), Cu (II), Pb (II) and Zn (II)) as part of the multi-component system from electrolyte solutions by means of electroflotation and filtration with presence of the high-molecular compounds (HMC) of different nature. • Effect of solution pH, metal and electrolyte concentration on the dispersed properties and electrokinetic potential of the dispersed low-soluble metal compounds and efficiency of their electroflotation removal. • Effect of HMC (flocculants and surfactants) with the anionic, cationic, non-ionic and amphoteric nature upon the dispersed properties, electrokinetic potential and efficiency of electroflotation and electroflotation with subsequent filtration removal of the low-soluble metal compounds particles in electrolyte solutions. • The efficiency of electroflotation removal of heavy metals from concentrated electrolyte solutions with the anionic HMS runs to 98–99% for all components. The process of removal of heavy metal ions as part of the multi-component system from electrolyte solutions by means of electroflotation and filtration with presence of the high-molecular compounds (HMC) of different nature has been studied. Studies were performed in solutions with ions of iron (III), nickel (II), copper (II), lead (II) and zinc(II), as well as NaCl and Na 2 SO 4 (pH 9.5–10.5). It has been shown that addition of the sulphate and sodium chloride mixture in 50 g/L concentration to solutions containing metal ions with total 0.1 g/L concentration reduced the absolute value of dispersed phase ζ-potential from −2.5 mV to −6 mV. The dispersed phase size is getting smaller, two particle types appear in the solution − 54 µm (72% of the total particle quantity) and 5.0 µm (28%). Rise of the total metal ion concentration up to 0.2 g/L results in reduction of the dispersed phase size: 1.5 µm (63%) and 46 µm (37%) particles prevail, the ζ-potential is reduced slightly (-7.1 mV). In this case, the rate of removal of the studied metals by mean of electroflotation is not more than 32–46%. Addition of the anionic HMS (flocculants and surfactants) to the solutions with the total concentration of metal ions of 0.2 g/L and salts of 50 g/L results in rise of dispersed phase ζ-potential and tends its value to the isoelectric point (±0 mV). When the cationic surfactants are added, the particle surface is recharged, the ζ-potential acquires the + values (5.3–7.8 mV). It has been concluded, that the rate of electroflotation removal of heavy metals from concentrated electrolyte solutions with the anionic HMS runs to 98–99% for all components. Subsequent solution filtration with the anionic flocculant allows for reduction of the residual concentration to the following values: 0.5∙10 -4 g/L for Fe (III), Cu (II) and Pb (II) ions and. 0.1∙10 -4 g/L for for Ni (II), 0.14∙10 -3 g/L for Zn (II). Addition of the cationic, non-ionic and amphoteric surfactants does not result in increase of electroflotation process efficiency.

Sorption Behavior of Grafted Porous Microparticles Based on Methacrylic Monomers and Chitosan/Gellan Gum towards Copper(II) and Nickel(II) Ions in Aqueous Solutions

AbstractThe present work investigates the sorption properties of grafted porous microparticles based on glycidyl methacrylate and chitosan/gellan gum for Copper(II) and Nickel(II) ions from the aqueous solutions. Batch sorption studies regarding the effects of various parameters, such as the chemical structure of the microparticles networks, the initial concentration of metal solution, pH value and contact time, were performed. The grafted porous microparticles obtained by suspension polymerization technique and loaded with metal ions were characterized by Fourier‐Transform Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive X‐Ray Analysis. The maximum loading capacities were: 41.70 (mg g−1) Copper(II)/39.27 (mg g−1) Nickel(II) for grafted microparticles with chitosan and 35.16 (mg g−1) Copper(II)/31.48 (mg g−1) Nickel(II) for those grafted with gellan, respectively. The equilibrium data were modeled by the Langmuir‐Freundlich, Langmuir and Dubinin‐Radushkevich isotherm models. The Lagergren, Ho, Elovich and Weber‐Morris particle diffusion models were applied to study the sorption kinetic mechanism. To highlight the efficiencies of the grafted porous microparticles as sorbents, four sorption/desorption cycles were performed. The results indicated that the grafted microparticles based on glycidyl methacrylate and chitosan/gellan gum could be used as sorbents for the removal of Copper(II)/Nickel(II) ions from aqueous solutions.

Autoclave dissolution of platinum metals in hydrochloric acid oxidizing media

The paper provides the results obtained in the study of the features of metallic platinum, rhodium and iridium dissolution in hydrochloric acid solutions under hydrothermal autoclave conditions. Hydrogen peroxide was used as an oxidizing agent. Solid and liquid phases were brought into contact after reaching a predetermined temperature, which is critically important in the study of rhodium black and platinum plate dissolution kinetics due to the high rates of these processes. The concentrations of metals in solutions were determined by atomic absorption spectroscopy and inductively coupled plasma mass spectrometry. The forms of rhodium, iridium, and platinum chlorocomplexes in solutions were determined using the spectrophotometric method. As a result of the experiments, the conditions of platinum plate and rhodium quantitative dissolution (in the form of affined powder and a plate) were determined and it was shown that at 210 °C in 6M hydrochloric acid as a medium with the addition of 5 vol.% hydrogen peroxide, iridium taken in the form of affined powder went into the solution by 50 % within more than 50 h, while the platinum plate dissolved completely at 130 °C in about 120 min. Kinetic data analysis using the shrinking core model showed that rhodium black and affined rhodium and iridium powders dissolve under autoclave conditions in a kinetic mode. The results obtained can be used both in analytical chemistry for the quantitative determination of inert platinum metals and in refining production to improve the technology for processing raw materials containing platinum group metals (PGMs) and to optimize approaches to the synthesis of pure chlorocomplex compounds of PGMs.

Determination of Cu and Pb concentrations based on urease activity inhibition of Durio zibethinus L. seeds

The determination of heavy metal concentrations has been carried out using sophisticated instruments, and therefore a simple and reliable alternative method is needed as a comparison. The study aimed to determine Cu and Pb concentration of standard solution using the urease activity inhibition method of Durio zibethinus L. seeds. The research started with urease extraction from Durio D. zibethinus L. seeds. The activity of the obtained extract was determined using the Nessler method. The optimum substrate concentration was also determined. Urease activity inhibition was carried out using various metal solution concentrations, which continued by plotting a log graph of urea concentration vs. %inhibition. The obtained graph would then determine the metal concentration in a synthetic water sample. The data was then compared to the measurement, determined by the Atomic Absorption Spectrophotometry (AAS) method. Results of the study showed that the urease activity of D. zibethinus L.seeds was 296.774 U/mL. Urease activity was optimum at a urea concentration of 0.3 M. The comparison Cu, and Pb concentration determination using the urease inhibitory activity and AAS methods showed no significant difference at 95% confidence level. This research showed that urease of D. zibethinus L. seed could be used to determine Cu and Pb's concentration based on its inhibiting activity.

Removal of cadmium and lead from aqueous solutions using iron phosphate-modified pollen microspheres as adsorbents

Abstract Iron phosphate-modified pollen microspheres (pollen@FePO4) were prepared and applied as sorbents for the removal of heavy metals (Cd2+ and Pb2+) from the aqueous solution. Batch sorption studies were conducted to investigate the effects of solution pH, contact time, sorbent dosage, and metal concentration on the adsorption process. The sorption of Cd2+ and Pb2+ ions on pollen@FePO4 corresponds to the pseudo-second-order model and Langmuir isotherm, which is similar to the unmodified pollen. At pH 5.92, pollen@FePO4 offers maximum adsorption capacities of 4.623 and 61.35 mg·g−1 for Cd2+ and Pb2+, respectively. The faster sorption kinetics and higher adsorption capacities of Cd2+ and Pb2+ ions onto pollen@FePO4 than pollen indicates that it might be a promising material for the removal of heavy metal ions in aqueous solutions. The possible adsorption mechanism involves electrostatic and chemisorption for Cd2+ and mainly complexion for Pb2+.

Breakthrough studies of the adsorption of lead from synthetic solution using Liagora viscida in a fixed bed column

AbstractConsidering the toxicity, the removal of heavy metals from the liquid effluent is of great significance. This article addresses the impact of the adsorbent bed height and flowrate on the adsorption performance and breakthrough curves in column studies. To explore the potential of Liagora viscida biosorbent, adsorption experiments were conducted in a packed column at various bed heights in the range of 2 to 6 cm and flow rates in the range of 10 to 20 ml/min. The maximum uptake of 53.90 mg/g has been achieved at the flow rate of 20 ml/min for an initial metal solution concentration of 20 ppm and pH and bed height of 6 and 2 cm, respectively. In the current study, the breakthrough (tb) and exhaust times (ts) correspond to 0.1 and 0.9, respectively. To predict the breakthrough characteristics, the experimental data were tested using Bohart‐Adam (B‐A), Bed Depth Service Time (BDST), Thomas, and Yoon‐Nelson (Y‐N) models. The experimental results confirmed that all three models except the Bohart‐Adams model were suitable for the experimental data with a good correlation coefficient.

The influences of operating conditions on the removal of Fe(II) in water by adsorption using bentonite as a low-cost adsorbent

The contamination of Fe2+ in groundwater is a problem that needs to be handled seriously as it can cause health problems for humans. In this study, the adsorption process method is conducted by use of natural bentonite from North Aceh. This process is expected to reduce Fe2+ as effectively as possible. The adsorption process is carried out by varying the contact time, adsorbent dose, and pH of the sample. The most effective contact time is obtained at 160 minutes, the adsorbent dose is 1 g/L and the pH of the sample is in neutral condition. With the initial concentration of metal in the sample solution of 20 mg/L, the adsorption process is able to remove 85.5% of Fe with the remaining Fe in the water of only 2.82 g/L.

Comparative Evaluation of Calcium, Magnesium, Copper and Zinc Removal by Wood Ash, Sodium Carbonate and Sodium Hydrogen Phosphate

Remediation via adsorption process has been proven to be one of the best water treatment technologies globally. Many adsorbents, including agricultural wastes, have been considered for the removal of a variety of pollutants from water. However, most of the studies reported in the literature used metal concentrations below 1000 ppm. It is also known that initial metal concentrations in polluted aqueous solutions, as well as metal and adsorbent type, are some of the factors that affect metal removal. Therefore, this project examined the remediation of water contaminated by 1000 ppm of lead, zinc, copper, magnesium, and calcium ions using wood ash, sodium hydrogen phosphate (dibasic), and sodium carbonate (dibasic). Comparative analysis of the results showed the order of order of metal removal by the adsorbents as: dibasic phosphate (Ca > Cu > Pb > Zn > Mg); dibasic Carbonate (Pb ~ Ca > Zn > Cu > Mg); Wood ash (Mg > Cu > Zn > Pb > Ca). These results suggest that metal and adsorbent type as well as the inherent chemical properties of these metal cations may contribute to the varying binding affinity of the metals to the adsorbent ligand(s) and thus, affect the extent of metal removal. It is equally worthy to note that wood ash more effectively removed hardness metals (Mg and Ca) from water than the inorganic phosphate and carbonate ions.