Metal Sorption Capacity Research Articles

Blast furnace slag and pine bark as potential filter media for metal sorption from landfill leachate

Heavy metals are commonly occurring in landfill leachate and in order to achieve theenvironmental goal about a non-toxic environment adopted by the Swedish Parliament, theleachate must be treated before being discharged into a nearby surface or groundwater body.There are several technical treatment options based on chemical, biological or physicalprocesses. Examples of these techniques are the SBR technique, oxidation and membranefiltration. These treatment methods are not always suitable at all landfill sites due toeconomical and/or technical constraints. Other treatment methods have therefore attractedattention. These methods, often natural based such as constructed wetland systems, are moreadapted to small landfill sites where high-tech and cost-demanding alternatives are not anoption. One natural based method that has attracted attention for leachate treatment in recentyears is the filter technique. It is based on the passage of a polluted water flow through a filtermedia with properties suitable for retention of heavy metals or other pollutants. A largenumber of different filter materials have been investigated with regard to their metal sorptioncapacity. The majority of these studies have been carried out in laboratory experiments ofdifferent kinds. Industrial by-products such as blast furnace slag and pine bark are filtermaterials that have been considered interesting for metal removal from landfill leachate. Aseries of laboratory experiments carried out as batch tests have therefore been conducted inorder to learn more about the potential of these filter materials to remove heavy metals fromlandfill leachate.

Sponge-based microfluidic sampling for potentiometric ion sensing

This work demonstrates an application of the new materials, sponges, for the use in microfluidic solution sampling integrated with ion-selective electrodes. The microfluidic sponge-based sampling was developed and studied as novel sampling and sample handling method to serve as alternative for microfluidic paper- and textile-based sampling for ion analysis in various environmental (Cd2+, Pb2+ and pH) and clinically (K+, Na+, Cl−) relevant samples. Three types of polyurethane, cellulose and natural sponges were used as substrates for microfluidic solution sampling. Polyurethane based sponge was found to have low heavy metal sorption capacity thus it was recognized as suitable for microfluidic sampling coupled with solid-state as well as solid-contact ion-selective electrodes. The application of sponge-based microfluidic sampling, contrary to previous findings of paper- and textile-based microfluidic sampling, allowed measurements of heavy metals without prior modification of the sampling substrate. Finally, the determination of potassium, sodium and chloride in wastewater sludge and sweat samples done with sponge-based microfluidic sampling integrated with ISEs was found similar to analysis done by ICP-OES and IC.

Cotransport of Herbaspirillum chlorophenolicum FA1 and heavy metals in saturated porous media: Effect of ion type and concentration

Predicting the cotransport of functional microorganisms and heavy metals in porous media is essential to both bioremediation and pollutant risk assessment. In this study, batch and column experiments were conducted to explore the cotransport behaviors of functional bacteria (FA1) and heavy metals (Pb2+/Cd2+) in saturated sand media under different conditions. The sorption capacity of heavy metals on FA1 was much greater than that of the sand, while both FA1 and sand showed stronger affinity to Pb2+ than Cd2+. The surface properties, especially zeta potential, of the bacteria and sand were altered by metal adsorption. As a result, the co-existence of Pb2+ decreased the transport of FA1 more significantly than that of Cd2+, and the influence was more significant with higher heavy metal concentration. On the other hand, the co-existence of FA1 inhibited the mobility of Pb2+ and Cd2+ in most scenarios, except when the cotransport concentration of Pb2+ was 5 mg L−1, and the inhibition was more pronounced for Pb2+ than Cd2+. Increase in metal concentrations decreased the FA1-associated Pb2+/Cd2+ in effluents due to the remarkable decrease in FA1 mobility, and free soluble Pb2+/Cd2+ became the major migration species. In addition, due to stronger attractive forces and affinity between Pb2+ and FA1, nearly all presorbed-Pb2+ by sand was remobilized by FA1 and transported mainly in FA1-associated form other than soluble Pb2+. Findings from this study indicated that the cotransport of biocolloids and heavy metals are highly sensitive to the ion type and concentration, and evaluation of their transport in the subsurface should be carefully carried out to avoid inaccurate estimations.

Study of the adsorption capacity of graphene oxide under gamma radiation in different media

The high surface area of graphene oxide (GO) and the different polar and oxygenated groups on its surface ensure its high sorption capacity for different metals from aqueous solutions. Moreover, its elevated stability under some harsh conditions could also allow the application of GO in real nuclear waste management. In this paper, the 241Am(III) and 152Eu(III) adsorption capacity of GO under γ radiation in different media (H2O; HNO3; and the metal Eu in HNO3) has been investigated. From our results, we conclude that GO in H2O and in presence of europium metal in HNO3 suffer a decrease in the adsorption capacity with the absorbed dose, which can be related to the structural damage that is proved with the characterization techniques employed (X-ray Diffraction (XRD), Raman spectroscopy and Thermogravimetric Analysis (TGA)). On the other hand, GO in acidic medium has the highest stability due to the GO structure protection for the effect of the acid medium.

Microwave‐Assisted Modification of Nanoalumina with Vitamin B3 as an Eco‐Friendly Nanosorbent for Trace Metals

Vitamin B3 (nicotinic acid, NA) is selected as an example of a promising environmental eco‐friendly metal sequestering reagent to functionalize the surface of nanoalumina‐loaded sodium dodecyl sulfate (nano‐Al2O3‐SDS) sorbent. This reaction is accomplished via microwave‐assisted heating using a solvent‐free approach for the formation of a novel nano‐Al2O3‐SDS‐NA sorbent. The functionalized nanomaterials are characterized by Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A comparative study is performed to explore and evaluate the sorption behaviors of nano‐Al2O3, nano‐Al2O3‐SDS, and nano‐Al2O3‐SDS‐NA sorbents for removal of Cu(II), Zn(II), and Pb(II) from aqueous solutions by the batch adsorption technique. The desired selectivity characteristics in the evaluated nanosorbents are confirmed from the determined maximum metal sorption capacity values of Cu(ΙΙ), Zn(II), and Pb(II) as 5700, 900, and 700 µmol g−1 by nano‐Al2O3‐SDS‐NA sorbent, respectively, using a 5 mg dosage. The optimum contact pH, time, initial metal ion concentration and competing species are also investigated. The Langmuir, Brunauer‐Emmet‐Teller and Dubinin–Radushkevich adsorption isotherm models are applied to evaluate the interaction processes of Cu(II), Zn(II), and Pb(II) by nano‐Al2O3, nano‐Al2O3‐SDS, and nano‐Al2O3‐SDS‐NA sorbents. The potential applications of these nanosorbents for adsorptive removal of metal cations from real samples are successfully optimized via a micro‐column technique.

Capability of Biowaste Composite of High Density Polythene with Egg Shell and Wood Sawdust for Sorption of Heavy Metals in Industrial Waste Water

The health hazards posed by heavy metals in water and the need to mitigate the hazards have attracteda flurry of research interests on the technologies and methods of removing them from water. The industrial waste waterfrom a gutter within the neighbourhood of the Delta Shopping Mall in Effurun was used to test the heavy metal sorptioncapacity of the waste high density polythene and biowaste composites compounded by the author using a locallyconstructed extruder. Some of the physico – chemical properties of the waste water determined with PH Kent meter (model7020) and Hach conductivity meter (C0150) where within WHO acceptable limits while some were not. The metalconcentrations were determined using Atomic Absorption Spectrometer(Perkin Elmer Absorption Analyst 400 model)The Composite of 2:1.5:0.5 (HDPE: saw dust: egg shell) sorbed the highest concentration of the metals ( 0.168mg/L, Fe;0.072mg/L, Ni and 0.082mg/L, Cr than the other composites of 1.5: 1: 1.5 and 2:1:1 except Cd while the composite, 2:1:1sorbed the least concentration of metals( 0.061mg/L, Fe; 0.044mg/L, Ni; 0.071mg/L, Cr and 0.002mg/L, Cd during thefirst 24 hours of sorption exposure. Chromium was the most sorbed metal, 97.6% while cadmium was the least, 20.0%.There was no systematic pattern of variation for metal absorption in the next 24 hours due probably to the blocking of thepore sites during the first twenty four hours of sorption exposure. The composite, 2:1.5:0.5 exhibited a good potential asan economic heavy metal sorbent.Keywords: Sorption capacity, heavy metals, composites, waste water, extruder

Mechanism of adsorption of cadmium and lead ions by iron-activated biochar

Heavy metal removal from aqueous matrices may help reduce disease and cancer incidences. In this study, reed biochar (RBC) and RBC modified by ferrous ammonium sulfate addition (1 mol Fe L-1) were compared for potential Cd and Pb removal from varying pH aqueous solutions. Surface functional groups were identified using Fourier transform infrared (FTIR) analysis, and their surface physicochemical structure was observed using scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). Batch experiments showed that the modified-reed biochar (MRBC) had greater Cd and Pb removal capacities over a wide pH range (1 to 8), as well as greater metal sorption capacities compared to RBC. Metal reaction kinetics occurred relatively quickly (i.e., within 60 min), and Langmuir modeling suggested that Cd and Pb removal by MRBC was maximized at 2.97 mg g−1 and 17.5 mg g−1 at 45 °C, respectively. The MRBC effectively sorbed Cd and Pb likely due to associations with functional groups modified by the Fe addition. In the future, MRBC may be used as an efficient and eco-friendly adsorbent for Cd and Pb removal from aqueous solutions and may help reduce water-borne issues associated with metal contamination.

Production of magnetic chitinous microcages from ephippia of zooplankton Daphnia longispina and heavy metal removal studies

This is the first study on production of three dimensional chitinous microcages from ephippial eggs of a microcrustacean, Daphnia longispina (water flea) by keeping the original shape of its chitinous structure. Iron-based magnetic particles were successfully loaded into the chitinous microcages to enhance its heavy metal sorption capacity. The FT-IR, SEM-EDX and TGA analysis proved the purity of chitin and demonstrated that the loading of magnetic particles into the chitinous microcages was achieved. These newly obtained three-dimensional chitin microcages and magnetic particles loaded microcages were tested in Cd(II), Cr(III), Cu(II), Ni(II) and Zn(II) removal from aqueous solutions. Magnetic particles loaded microcages exhibited a better performance in removal of Cd(II), Cu(II) and Ni(II) ions; while unloaded microcages showed a higher affinity for Cr(III) and Zn(II). This study demonstrated that the chitin microcages are suitable carriers for iron-based magnetic particles. Here these new materials were studied only for removal of five heavy metal ions but these promising materials have a potential to be used in various fields.

CHITOSAN-BASED ADSORBENTS FOR THE REMOVAL OF METAL IONS FROM AQUEOUS SOLUTIONS

Wastewater containing heavy metal ions is one of the most serious environmental concerns. Exposure to elevated levels of heavy metals can adversely affect water resources, endangering the ecosystems and human health. Among the various treatment technologies, adsorption using biopolymer seems a promising alternative method. Chitosan is a natural polymer produced from chitin with excellent properties such as biocompatibility, biodegradability and non-toxicity. Moreover, chitosan is known as an effective sorbent due to the presence of amino and hydroxyl groups in its molecules which can serve as attachment sites towards metal ions. Recently, chitosan derivatives as metal ion sorbents have gained considerable attention. These derivatives are prepared by either physical or chemical modifications or both in order to improve chitosan properties in adsorption. This paper discusses recent developments in the modifications of chitosan and the application of the derived materials in the removal of metal ions from aqueous solutions. The mechanisms of adsorption, metal sorption capacities, effect of pH, isotherm and kinetic models are also described.

Simultaneous cationic Cu (II)‒anionic Sb (III) removal by NH2-Fe3O4-NTA core-shell magnetic nanoparticle sorbents synthesized via a facile one-pot approach.

In this study, a regenerable magnetic core-shell nanoparticles NH2-Fe3O4-NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe3O4 was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH2-Fe3O4-NTAII was prepared by multi-step method for comparison. NH2-Fe3O4-NTA had positive zeta potential values of 35.1-0.8 mV at pH 1.8-11.0, with the saturation magnetization and surface area up to 40.56 emu/g and 56.94 m2/g, respectively. The maximum sorption capacities of NH2-Fe3O4-NTA for cationic Cu (II) and anionic Sb (III) were 55.56 and 51.07 mg/L, respectively, which were superior to that of NH2-Fe3O4-NTAII. Based on screening in terms of characterization and metal sorption capacity, NH2-Fe3O4-NTA with a feasible synthesis scheme was chosen for further evaluation. The Cu (II) removal by NH2-Fe3O4-NTA was favored with increasing pH, while the Sb (III) removal preferred low pH (2-3). Simultaneous sorption of Cu (II) and Sb (III) exhibited same removal performance with the sole sorption under high dosage (>1 g/L). In real wastewater applications of NH2-Fe3O4-NTA, multiple metals in actual wastewater could be removed to well below the regulation levels. Nonspecific electrostatic interactions, inner-sphere complexation, ligand exchange, chelation and coordination complexation were responsible for Cu (II) and Sb (III) removal.

Co-transport and remobilization of Cu and Pb in quartz column by carbon dots

Carbon nanoparticles such graphene, carbon nanotubes, and carbon dots offer the potential to improve environmental treatment technologies due to their unique properties such as low toxicity and high metal sorption capacity. However, there are no studies on facilitated transport and remobilization of pre-sorbed metals by carbon dot (CD) nanoparticles in quartz sand columns. Here, we investigate the effects of solution ionic strength (IS; 1, 100 and 200 mM NaCl) and pH (Chen et al., 2017; Chen et al., 2010; Cornell and Schwertmann, 2006), initial CD concentration (200, 400, 600 and 800 mg L−1), and clay content (10, 20 and 30%w kaolinite) in quartz sand columns on the transport, retention and remobilization of Cu and Pb in saturated (upward flow) quartz porous media. Batch sorption experiments were employed to underpin the findings of the column transport experiments. Both CD and quartz adsorbed Cu and Pb from water, but adsorption was higher on CD than quartz.Co-transport experiment demonstrated the CD-facilitated transport of Cu and Pb. Sequential transport experiments (first three phases) demonstrated the retention of Cu and Pb in the quartz column, with higher retention of Pb compared to Cu. The Cu and Pb retention was attributed to their sorption on the quartz grains and precipitation under the experimental conditions investigated in this study. Cu retention increased with the increase in ionic strength, pH and clay content. Pb was nearly totally retained in the quartz column at all experimental conditions. The subsequent injection of CD resulted in Cu and Pb remobilization to different extents, except in the presence of high kaolinite concentration. CD is most efficient in remobilizing Cu and Pb at 400 mg L−1 CD concentration and under low ionic strength (ca. 1–100 mM), low pH (ca. 6) and in the absence of clays. Deviation from these conditions results in reduced remobilization of Cu and Pb.

Imprinting “Nano-SiO2-Crosslinked Chitosan-Nano-TiO2” Polymeric Nanocomposite for Selective and Instantaneous Microwave-Assisted Sorption of Hg(II) and Cu(II)

An imprinting polymeric nanocomposite-like structure was synthesized by bonding crosslinked chitosan to nano-SiO2 and nano-TiO2 simultaneously via bifunctional glutaraldehyde linker. The structure of this “nano-SiO2-crosslinked chitosan-nano-TiO2” nanocomposite was confirmed and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The surface area (6.47 cm3 g–1), porosity (0.193 cm3 g–1), and particle size (14–40 nm) were confirmed from scanning electron microscopy (SEM) studies, high-resolution transmission electron microscopy (HR-TEM) studies, and surface area measurements. This nanocomposite announced selective and enhanced sorption for Hg and Cu ions with high performance using microwave techniques. Different factors that affected the metal sorption capacity were monitored, including microwave-contact time, pH, nanocomposite dosage, temperature, and initial metal concentration. Maximum capacity values of 8000 and 4000 μmol g–1...

Effect of feed source and pyrolysis conditions on properties and metal sorption by sugarcane biochar

Abstract Sugarcane biomass from different feed sources of sugar mill operation were used in producing biochar at different temperatures (350, 500, 650, and 800 °C) with/out steam activation at 800 °C. Feed sources included fresh cane-trash, fresh bagasse, and old bagasse collected from a pile left outside the plant for several years. Biochar yield and composition were determined and metal sorption capacity evaluated. Pyrolysis more than doubled biochar ash content which was 2 to 3 times higher for fresh cane trash and old bagasse than for fresh bagasse biochars. On the other hand, surface area of fresh bagasse activated biochars (493 m2 g−1) nearly doubled that of the old bagasse (262 m2 g−1), or fresh cane trash (204 m2 g−1) biochars. Cadmium sorption capacity increased upon activation and was an order of magnitude higher for old bagasse biochars than for fresh bagasse or fresh cane trash biochars across production temperatures (ranging from 43.4 mg g−1 to 63.8 mg g−1 compared to 0.35 mg g−1 to 0.47 mg g−1, or 4.35 mg g−1 to 6.29 mg g−1, respectively). Maximum sorption capacity for Cd and Cu was highly correlated with biochar ash content, while that of Pb correlated with biochar surface area and total sulfur content. Cu sorption capacity inversely correlated with O/C ratio and reduced significantly upon acid washing of activated 500 °C old bagasse biochar (from 32.2 mg g−1 to 14.3 mg g−1). Ash content seemed to play a decisive role in metal sorption capacity of sugarcane bagasse biochars. Overall, old sugarcane bagasse feedstock demonstrated best performance in producing biochars of higher metal sorption capacity compared to fresh cane-trash or fresh bagasse.

Removal of Cu(II), Cd(II) and Pb(II) ions from aqueous solutions by biochars derived from potassium-rich biomass

Abstract: This work evaluated the novel application of biochars derived from potassium (K)-rich feedstock (banana peels (BB) and cauliflower leaves (CB)). The sorptive property of the produced biochars was evaluated with multi-element [Copper (Cu(II)), Cadmium (Cd(II)) and Led (Pb(II))] sorption experiments. Morphologies of the pre- and post-sorption samples were characterized using SEM/EDS and XRD spectra analyses. The produced biochar was further subjected to mono-element sorption studies to explore the effect of the pH value of the sorbate solution on the removal efficiency of Cu(II), Cd(II) and Pb(II) ions. Biochar productivity was noticeably high (61.44 and 64.66% for BB and CB, respectively) due to the catalytic action of K during the pyrolytic conversion of the feedstock. K-minerals were the predominant on the XRD patterns of both biochars. Metal sorption capacity of BB was much greater than that of CB due to its higher electrostatic attraction, which was the predominant mechanism governed sorption process. Sorption of metal ions onto BB and CB was pH-dependent as the sorption capacity increased significantly with the increase of the pH value of sorbate solutions (6.0 with Cu(II), Pb(II) and 8.0 with Cd(II)). Dynamics of metal ions sorption onto biochars showed competitive sorption following the order: Pb(II) > Cu(II) > Cd(II).

Removal of metals from industrial wastewater and urban runoff by mineral and bio-based sorbents

The study was performed to evaluate chemically modified biosorbents, hydrochloric acid treated peat (HCl-P) and citric acid treated sawdust (Citric acid-SD) for their metal removal capacity from dilute industrial wastewater and urban runoff and compare their efficiency with that of commercially available mineral sorbents (AQM PalPower M10 and AQM PalPower T5M5 magnetite). Batch and column experiments were conducted using real water samples to assess the sorbents' metal sorption capacity. AQM PalPower M10 (consisting mainly of magnesium, iron and silicon oxides) exhibited excellent Zn removal from both industrial wastewater and spiked runoff water samples even at low dosages (0.1 g/L and 0.05 g/L, respectively). The high degree of Zn removal was associated with the release of hydroxyl ions from the sorbent and subsequent precipitation of zinc hydroxide. The biosorbents removed Ni and Cr better than AQM PalPower M10 from industrial wastewater and performed well in removing Cr and Cu from spiked runoff water, although at higher dosages (0.3–0.75 g/L). The main mechanism of sorption by biosorbents was ion exchange. The sorbents required a short contact time to reach equilibrium (15–30 min) in both tested water samples. AQM PalPower T5M5 magnetite was the worst performing sorbent, leaching Zn into both industrial and runoff water and Ni into runoff water. Column tests revealed that both HCl-P and AQM PalPower M10 were able to remove metals, although some leaching was witnessed, especially As from AQM PalPower M10. The low hydraulic conductivity observed for HCl-P may restrict the possibilities of using such small particle size peat material in a filter-type passive system.

Continuous leaching modifies the surface properties and metal(loid) sorption of sludge-derived biochar

After the application of sludge derived biochar (SDBC) for soil stabilization, it is subjected to continuous leaching that may change its surface properties and metal(loid) immobilization performance. This study simulated the continuous leaching through the fresh SDBC sample in columns with unsaturated and saturated zones under flushing with 0.01M NaNO3 solution (pH5.5) and acidic solution (pH adjusted to 3.2 by HNO3:H2SO4=1:2), respectively. The resultant changes were assessed in terms of the SDBC surface characteristics and metal(loid) sorption capacities. Continuous leaching was found to gradually decrease the density of basic functional groups and increase the density of carboxyl groups as well as cation exchange capacity on the SDBC surface. It was attributed to the surface acidification and oxidation process by the leaching process, yet it occurred to a lesser extent than the atmospheric exposure. Continuous leaching increased Pb(II), Cr(VI), and As(III) sorption capacity of the SDBC, probably because the increase in carboxyl groups promoted inner-sphere complexation and Fe oxidation as revealed by spectroscopic analysis. It was noteworthy that the SDBC in the unsaturated and saturated zones under continuous leaching displayed distinctive effects on metal(loid) sorption capacity than the atmospheric exposure. Future investigations are needed for understanding the fate and interactions of the SDBC under varying redox conditions and intermittent leaching process.

Predicting Cu and Zn sorption capacity of biochar from feedstock C/N ratio and pyrolysis temperature

Biochars have been proposed for remediation of metal-contaminated water due to their low cost, high surface area and high sorption capacity for metals. However, there is a lack of understanding over how feedstock material and pyrolysis conditions contribute to the metal sorption capacity of biochar. We produced biochars from 10 different organic materials by pyrolysing at 450 °C and a further 10 biochars from cedar wood by pyrolysing at 50 °C intervals (250–700 °C). Batch sorption experiments were conducted to derive the maximum Cu and Zn sorption capacity of each biochar. The results revealed an exponential relationship between Cu and Zn sorption capacity and the feedstock C/N ratio and a sigmoidal relationship between the pyrolysis temperature and the maximum Cu and Zn sorption capacity. FTIR analysis revealed that as temperature increased, the abundance of functional groups reduced. We conclude that the high sorption capacity of high temperature biochars is due to an electrostatic attraction between positively charged Cu and Zn ions and delocalised pi-electrons on the greater surface area of these biochars. These findings demonstrate a method for predicting the maximum sorption capacity of a biochar based on the feedstock C/N ratio and the pyrolysis temperature.

Relationship of Biodiversity with Heavy Metal Tolerance and Sorption Capacity: A Meta-Analysis Approach.

Microbial remediation of metals can alleviate the concerns of metal pollution in the environment. The microbial remediation, however, can be a complex process since microbial metal resistance and biodiversity can play a direct role in the bioremediation process. This study aims to understand the relationships among microbial metal resistance, biodiversity, and metal sorption capacity. Meta-analyses based on 735 literature data points of minimum inhibitory concentrations (MIC) of Plantae, Bacteria, and Fungi exposed to As, Cd, Cr Cu, Ni, Pb, and Zn showed that metal resistance depends on the microbial Kingdom and the type of heavy metal and that consortia are significantly more resistant to heavy metals than pure cultures. A similar meta-analysis comparing 517 MIC values from different bacterial genera (Bacillus, Cupriavidus, Klebsiella, Ochrobactrum, Paenibacillus, Pseudomonas, and Ralstonia) confirmed that metal tolerance depends on the type of genus. Another meta-analysis with 195 studies showed that the maximum sorption capacity is influenced by microbial Kingdoms, the type of biosorbent (whether consortia or pure cultures), and the type of metal. This study also suggests that bioremediation using microbial consortia is a valid option to reduce environmental metal contaminations.

Enterosorption Properties of Arctic Brown Algae Fiber

Enterosorption properties of algae fiber were studied. Determination of the thermodynamic characteristics of heavy metal sorption showed that the process is endothermic with the prevalence of chemisorption interactions. Algae fiber exhibits high sorption capacity for heavy metals and pathogenic microorganisms.

Evaluation of Green Waste and Popular Twigs Biochar Produced at Low and High Pyrolytic Temperature for Efficient Removal of Metals from Water

Biomass-derived biochar is considered as a promising heavy metal adsorbent, due to its favorable physicochemical properties, from aqueous solution as compared with other adsorbents. However, there is a limited number of studies on the effects of biochar produced from different feedstocks and pyrolytic temperatures on metal removal from metal-contaminated water. So in this study, the removal of the most prevalent heavy metals [(lead (Pb(II)), cadmium (Cd), and chromium (Cr)] by green waste biochar (GWB) and popular twigs biochar (PTB), produced at different pyrolytic temperatures, i.e., low 350 and high 650 °C, has been investigated, following the determination of physical and chemical properties of biochar. The efficiency of heavy metals removal of biochar was studied at different concentrations of heavy metals (10 and 100 μg mL−1), biochar types and treatment duration (3, 6, 9, and 12 h) at isothermic condition of aqueous solution. Results revealed that both feedstock type and pyrolytic temperature to produce biochar significantly affected its metal sorption capacity. The maximum sorption capacities of all three metals, i.e., Pb (II), Cd, and Cr were determined in the GWB produced at low pyrolytic temperature 350 °C after 9 h of treatment duration at both high and low metal concentrations. This highest sorption capacity of all metals by low pyrolytic temperature produced GWB was due to its better physicochemical properties especially high surface area, cation exchange capacity, and oxygen-containing functional groups as compared with woody feedstock based high pyrolytic temperature produced PTB. Conclusively, low pyrolytic temperature produced GWB was evaluated as a potential adsorbent to efficiently reduced heavy metal concentration in metal-contaminated water.