SEM-EDX Results Research Articles

Stabilization of lead (Pb)- and arsenic (As)-contaminated soil using pen shells (Atrina pectinata).

Pen shells (PS), a type of shellfish, are abundantly consumed, and their inedible shell residues are often discarded near the coast without consideration of reutilization. This study sought to investigate the use of natural pen shells (NPS) and calcined pen shells (CPS) to stabilize Pb and As-contaminated soil. During the investigation, NPS and CPS were applied to the contaminated soil in amounts ranging from 1 to 10 wt% and cured for 28days. After the curing process, the mineral phase was examined through X-ray powder diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analysis. The XRD and SEM-EDX results revealed the presence of riversideite and ettringite, which contribute to Pb and As stabilization in the CPS-treated soil. The leachability of Pb and As in the treated soil was further examined with three types of chemical extraction methods. Extraction results using 0.1M HCl displayed a notable pH fluctuation in the extractant due to the residual amendments (NPS and CPS). The fluctuation resulted in a strong correlation of leached Pb and As with the pH of the extractant, which might hinder an accurate assessment of stabilization. In order to minimize the effect of pH, an EDTA-NH4OAc extraction was employed, suggesting its potential as a suitable assessment method. EDTA-NH4OAc extraction showed a higher effectiveness of CPS than NPS at 10 wt% of input amounts. In the SBET extraction, that uses a strongly acidic solution, a higher As leachability was observed by increasing the addition of CPS, which implied a CPS-related chemical fixation mechanism. The comparison of various extraction methods showed a higher CPS effectiveness as compared to NPS. However, it was recommended that CPS-treated soil required caution in strongly acidic conditions, especially for arsenic. This study explores the applicability of PS, which has not been investigated as an amendment for Pb and As-contaminated soil previously. Furthermore, this study revealed that utilization of various extraction methods is beneficial for gaining a comprehensive understanding of the role of CaCO3-based amendment in Pb and As-contaminated soil.

Earthworm excrete derived-enzyme enriched SnO2/g-C3N4 nanocomposite for near complete decomposition of toxic dye molecules

Enzymes derived from earthworm (Eudrilus eugeniae) excretes (vermiwash) were used as supporting bio-catalysts with SnO2/g-C3N4 nanocomposites for photocatalytic dye degradation of toxic organic dyes. The results were compared to those of the composite partners SnO2 and g-C3N4. The enzyme supported nanocomposite has superior photocatalytic efficiency of 95 %, 93 %, 83 % and 97 % against the test dyes Methylene Blue (MB), Malachite Green (MG), Methyl Orange (MO) and Rose Bengal (RB) whereas the partners SnO2 (62 %, 81 %, 36 % & 73 %) and g-C3N4 (76 %, 84 %, 80 % & 89 %) exhibited lower efficiencies. The enzymes phosphatase, amylase, urease and protease present in the synthesized nanocomposite play supporting role as co-catalyst in enhancing the photocatalytic ability of the nanocomposite. The mechanism involving the charge carrier recombination delay due to the formation of g-C3N4 sheets beneath the SnO2 particles is illustrated. The partnering mechanism with g-C3N4 having lower bandgap (2.8 eV) leads to a reduction in the bandgap from 3.5 eV for SnO2 to 2.6 eV for the nanocomposite making the nanocomposite as visible light responsive photocatalyst. The XRD, FTIR, SEM-EDX, UV–vis–NIR, XPS and DFT results support the discussion on photocatalytic mechanism. The near complete dye degradation is confirmed by phenotypic test on earthworm (Eudrilus eugeniae).

Heavy Metal Removal from Aqueous Solutions Using a Customized Bipolar Membrane Electrodialysis Process.

Lack of safe water availability and access to clean water cause a higher risk of infectious diseases and other diseases as well. Heavy metals (HMs) are inorganic pollutants that cause severe threats to humans, animals, and the environment. Therefore, an effective HM removal technology is urgently needed. In the present study, a customized bipolar membrane electrodialysis process was used to remove HMs from aqueous solutions. The impacts of the feed ionic strength, applied electrical potential, and the type and concentration of HMs (Cd2+, Co2+, Cr3+, Cu2+, and Ni2+) on the process performance were investigated. The results showed that feed solution pH changes occurred in four stages: it first decreased linearly before stabilizing in the acidic pH range, followed by an increase and stabilization in the basic range of the pH scale. HM speciation in the basic pH range revealed the presence of anionic HM species. The presence of HMs on anion exchange membranes confirmed the contribution of these membranes for HM removal in the base channels of the process. While no clear trend was seen in the ionic strength solution, the maximum HM removal was observed when 1.5 g/L NaCl was used. The initial HM concentration showed a linear increase in HMs removal of up to 30 mg/L. A similar trend was seen with an increase in the applied electrical potential of up to 15 V. In general, the amount of HMs removed increased in the following order: Cd2+ ˃ Ni2+ ˃ Co2+ ˃ Cu2+ ˃ Cr3+. Under some operational conditions, however, the removed amount of Cu2+, Co2+, and Ni2+ was similar. The mass balance and SEM-EDX results revealed that the removed HMs were sorbed onto the membranes. In conclusion, this process efficiently separates HMs from aqueous solutions. It showed the features of diluate pH adjustment, reduction in the overall stack electrical resistance, and contribution of anion exchange membranes in multivalent cation removal. The mechanisms involved in HMs removal were diffusion and migration from the bulk solution, followed by their sorption on both cation and anion exchange membranes.

Uptake, translocation, and nutrient efficiency of nano-bonechar as a plant growth regulator in hydroponics and soil systems

The use of nanotechnology in terms of nanoparticles, carbon nanotubes, and quantum dots, when exposed to the plants, helps increase their productivity. It is worth the effort to comprehend the fate of these nanoparticles in plants. Bonechar derived from bones is a rich source of C, P, Ca2+, and Mg2+ nutrients, which can significantly contribute to the growth of the plants. This study focused on the uptake of nano-bonechar (NBC) in the Syngonium podophyllum plant, and its effects on plant growth under hydroponics and soil systems. The compound microscopy and SEM-EDX results confirmed the presence of NBC in the leaves and roots of the plants in hydroponics and soil systems. The FTIR spectra reflected the presence of functional groups of the NBC in the leaves of the Syngonium podophyllum plant. The plant's growth parameters showed an increase in fresh weight, dry weight, shoot length, chlorophyll content, leaf count, total Ca2+, total PO43−, and total organic carbon of plants in both systems. The NBC not just improved plant physiochemical parameters but also built up the soil quality in terms of bioavailable Ca2+, PO43−, water holding capacity, and soil organic matter. It is concluded that the production of carbon-based NBC not only helps manage bone waste but also their efficient uptake in plants significantly improving plant productivity.

Activity and Durability of ALD-ZrO2 Coated IrO2 Film in Sulfuric Acid

The technology of power-to-gas (P2G) is drawing attention in and outside Japan for its ability to store renewable energy as hydrogen [1]. For the aspect of P2G, the water electrolyzer plays important role to produce “Green Hydrogen” [2]. On Sep. 26, 2022, Hydrogen energy ministerial meeting was held as online special event. In the open session, the water electrolysis is one of the main topics of the session, and due to the demand for “Green Hydrogen”, installed capacity of water electrolyzer has been required for the huge size of its module [3].In Japan, proton exchange membrane water electrolysis (PEMWE) with small size produced by Kobelco Eco-Solutions Corp have released already installed over 200 units for 25 years. Recently, the PEMWE with MW-class as installed in Yamanashi Hydrogen Company has also applied for the demonstration project [3]. However, the conventional electrocatalysts for PEMWE uses precious metal materials, and especially, the iridium oxide (IrO2) is used as an anode. As the iridium is by-product of platinum, its resources is very poor. Moreover, it is reported that the low loading of IrO₂ easily causes the degradation under dynamic operation condition simulated variable renewable energies (VRE) [4]. From this point of view, the durability of anode against VRE should be required for “Green Hydrogen” production. We focused on ZrO2 which has high stability in acidic solution [5]. Moreover, we found that an oxide-based film which is formed by Atomic Layer Deposition (ALD) showed bi-functional effects on the electrocatalyst for the oxygen reduction reaction; it can reflect the electrochemical properties of the substrate and it can also protect the consumption of the substrate by potential scan. In order to apply for PEMWE, we have investigated the catalytic activity of IrO2 electrodes deposited with ZrO2 using ALD for the oxygen evolution reaction (OER).IrO2 film on Ti rod as substrate was fabricated by thermal decomposition under air atmosphere at 400°C for 10 min. The loading amount of IrO2 was 2.35 mg cm-2 at constant. ZrO2 was deposited on IrO2 film by using ALD at 225°C, the film thickness of ZrO2 was varied in the range of 2 to 10 nm that calculated from the number of ALD cycles. After coating, the heat treatment was performed under air atmosphere at 400oC for 10 min. We used conventional three electrode cell with each sample as working electrode while the reversible hydrogen electrode (RHE) and carbon plate were used as reference and counter electrode to demonstrate the electrochemical measurement in 1 M H2SO4 at 303 K. After the pretreatment, the cyclic voltammetry was demonstrated in the range of 0.05 to 1.2 V. In order to evaluate the OER activity of samples, the slow scan voltammetry (SSV) was performed from 1.2 to 2.0 V vs. RHE.Figure 1 shows the polarization curves of OER on the ALD-ZrO2 of 5 nm coated on IrO2 with and without heat treatment (5nm, 5nm(HT)). The result of IrO2 with and without heat treatment (0nm, 0nm(HT)) are also shown in the Fig. 1. These results are IR-free data. The vertical axis is based on geometric current density (i geo). In the case of IrO2, the i geo of 0nm was larger than 0nm(HT). On the other hand, the i geo of 5nm(HT) was obviously larger than that 5nm in the case of ALD-ZrO2 of 5 nm coated on IrO2, and the i geo of 5nm(HT) at 1.55 V was almost same as that of 0nm(HT). The redox peak of Ir(IV)/Ir(V) or Ir(IV)/Ir(VI) was observed in the cyclic voltammogram (CV) of 5nm(HT) around 1.2 V. This peak also obtained in the CVs of both 0nm and 0nm(HT). However, it is not clearly shown in the CV of 5nm. From the results of SEM-EDX, the coating of ZrO2 of 5nm(HT) was remained after electrochemical measurement while the that of ZrO2 of 5nm was removed after electrochemical measurement. Therefore, the heat treatment after ALD coating was effective for enhancing OER activity.Acknowledgement: This work is partially supported by the Suzuki Foundation and JFE 21st Century Foundation.Reference Fuel Cell RD & D in Japan 2022, Fuel Cell Development Information Center (FCDIC), pp.8. Fuel Cell Development Information Center (FCDIC), Tolyo (2023).K. Ota, A. Ishihara, K. Matsuzawa, and S. Mitsushima, Electrochemistry, 78, 970 (2010).https://www.meti.go.jp/english/press/2020/1015_001.html M. Alia, and G. C. Anderson, J. Electrochem. Soc., 166, F282 (2019).A. Ishihara, Y. Ohgi, K. Matsuzawa, S. Mitsushima, and K. Ota, Electrochim. Acta, 55, 8005 (2010). Figure 1

The Influence of Silica Dioxide in the Electrocatalytic Performances of rGO/Fe<sub>3</sub>O<sub>4</sub> as Oxygen Reduction Electrocatalyst

In this study, synthesis of reduced graphene oxide-iron oxide-silica dioxide (rGO/Fe3O4/SiO2) was done through a facile chemical process. Physical characterization was carried out as such Fourier transform infrared spectroscopy (FTIR) which confirmed the presence of silica peak in the spectrum of rGO/Fe3O4/SiO2, while RAMAN displayed the vibrational bands of carbon materials studied. Results of SEM-EDX and TEM confirmed the unification of SiO2 on rGO/Fe3O4 nanocomposite with difference in morphologic structure. X-ray diffraction (XRD) analysis exhibited that addition of SiO2 increased the crystalline size of the nanocomposite. Nitrogen adsorption isotherm analysis describes the nanocomposites fall in the mesopore region. The nanocomposite was then drop-casted on the surface of glassy carbon electrode (GCE) for fabrication of the electrode which denoted as rGO/Fe3O4/SiO2/GCE. Electrochemical characterization of modified electrode was studied using electron impedance spectroscopy (EIS), which showed the minimal resistance charge transfer. Oxygen reduction reaction analysis shows that electrocatalytic reduction of oxygen was excellent with four-electron transfer when calculated using Randles-Sevcik equation. All the analysis was compared to the nanocomposites without the addition of silica oxide (rGO/Fe3O4). This work proves that addition of nanoparticle in a compound as a matrix improves the oxygen reduction potential of rGO/Fe3O4/SiO2/GCE composite.

Preparation of infiltrating calcium carbonate layer in gypsum substrate using novel calcium precursor: The implication for the protection of the surface weathered carbonate heritages from water erosion damage

Surface gypsification is a common problem for calcium carbonate historic construction materials. In this paper, a calcium carbonate protective layer was prepared in gypsum substrate using alcohol solution of calcium hydroxy glycolate. The concentration and penetration depth of alcohol solution of calcium hydroxy glycolate are as high as 2.0 M and 18.0 mm, respectively, which guarantees the sufficient introduction of calcium precursor at single treatment. Additionally, after introducing into gypsum substrate, calcium hydroxy glycolate can be transformed into calcium carbonate layer in the open air only when water was introduced subsequently, indicating that the calcium hydroxy glycolate is completely controllable in application. The results of FT-IR, SEM-EDX, XRD, IC and conductivity demonstrate that the prepared stable calcite layer can prevent the gypsum substrate from water corrosion efficiently. This exploring study provides a new solution for the protection of surface gypsification carbonate materials in the ancient constructions and relics.

Effect of Si/Al Molar Ratio on Zeolite Synthesis from Nipah Leaf and Used Canned Alumunium

Silica and alumunium are the main sources in the manufacture of synthetic zeolite which will be engineered in such a way that it contains the same character as natural zeolite. The silica content in Nipah leaf waste is 26,28 % and the alumunium content in used cans is 53,09 %, it has the potential to be the main ingredient in zeolite synthesis. This study aims to determine the effect of Si/Al molar ratio on synthetic zeolite characteristics. Making zeolite is done by mixing silica and alumunium as well as the zeolite crystallization process using a hydrothermal reactor. Characterization of zeolite was carried out by morphological analysis and elemental composition using SEM-EDX and functional group analysis using FTIR. The results of SEM-EDX show the morphology and composition of zeolite forming elements included in low sillica zeolite, and FTIR results show functional groups of synthetic zeolite in the form of double rings at wavevumbers 500 – 650 cm-1, and the presence of zeolite finger prints at wavenumbers 700 – 1100 cm-1.

Fe2O3/coal fly ash Fenton-like catalyst for the elimination of organic pollutants in wastewater: Kinetic, mechanism, and application feasibility

Fe2O3/CFA was prepared by loading Fe2O3 on the surface of raw coal fly ash (RCFA), and then used as a Fenton-like catalyst to treat refractory organic wastewater. The characterization results of SEM-EDX, XRD, XPS, XRF, and BET test indicate that Fe2O3 is successfully loaded on the surface of RCFA, while the adsorption performance is not significantly affected. Under optimal treatment conditions of p-nitrophenol (PNP) simulated wastewater (H2O2 dosage = 8 mmol/L, Fe2O3/CFA loading = 6 g/L, pH = 3, and T = 303 K), the removal rate of PNP reaches 97.7 % at 50 min. There exist hydroxyl radicals (·OH), superoxide radicals (∙O2−) and singlet oxygen (1O2) in the Fenton-like system, and ·OH is the primary reactive oxygen species in the removal of PNP·H2O2 dosage, Fe2O3/CFA loading, and pH (i.e., [H+]) show different effects on the generation rate constant of hydroxyl radicals (k·OH), and the corresponding mathematic equation is k∙OH=6.51∙e−640.0T∙[H2O2]1.313∙[Fe2O3/CFA]1.093∙[H+]0.815. The Fenton-like process includes heterogeneous and homogeneous catalytic processes, and it is driven by the synergistic catalysis of multiple metallic elements; Fe and other metallic elements play major and auxiliary roles, respectively. In the advanced treatment of real coking wastewater, the catalytic capacity of Fe2O3/CFA can maintain 91.7 % in its 4th use, and the treatment cost is ¥4.15/ton, which can be decreased by further optimizing the preparation process of Fe2O3/CFA.

COMPARATIVE STUDY the ACTIVITY in DRY REFORMING of METHANE of BIOXIDE NiO-Co3O4 and NiO-Fe2O3 SYSTEMS SUPPORTED on the GRANULATED NATURAL DIATOMITE

In this work, catalytic systems NiO-Co3O4 and NiO-Fe2O3 bioxide supported on the granulated natural diatomite from the Georgia deposit were investigated as catalysts for the dry reforming of methane. The results showed that the NiO-Co3O4/D catalyst is more active and stable than NiO-Fe2O3/D. At the reaction temperature 850 oC the conversion of methane on the NiO-Co3O4/D catalyst was 77%, whereas on the NiO-Fe2O3/D – 42%. The activity of the NiO-Co3O4/D catalyst in the reaction is probably due to the high dispersity of the catalyst particles. The results of SEM-EDX, XRD, and AES showed that cobalt oxide in the composition of NiO-Co3O4/D is in the form of nanoparticles with sizes much smaller than the sensitivity threshold of X-ray diffraction analysis (<100Å).

The Catalytic Upgrading Performance of NiSO4 and FeSO4 in the Case of Ashal’cha Heavy Oil Reservoir

Aquathermolysis is a promising process for improving the quality of heavy oil under reservoir conditions. However, the application of catalysts during the process can significantly promote the transformation of the heavy fragments and heteroatom-containing compounds of crude oil mixtures into low-molecular-weight hydrocarbons. This research paper conducted a comparative analysis of the catalytic effectiveness of water-soluble metal salts like NiSO4 and FeSO4 in the process of aquathermolysis to upgrade heavy oil samples extracted from the Ashal’cha reservoir. The temperature of the experiment was 300 °C for a duration of 24 h. Compared to the viscosity of the native crude oil, the Fe nanoparticles contributed to a 60% reduction in viscosity. The viscosity alteration is explained by the chemical changes observed in the composition of heavy oil after catalytic (FeSO4) aquathermolysis, where the asphaltene and resin contents were altered by 7% and 17%, accordingly. Moreover, the observed aquathermolytic upgrading of heavy oil in the presence of FeSO4 led to an increase in the yield of gasoline fraction by 13% and diesel fraction by 53%. The H/C ratio, which represents the hydrogenation of crude oil, increased from 1.52 (before catalytic upgrading) to 1.99 (after catalytic upgrading). The results of Chromatomass (GC MS) and Fourier-transform infrared spectroscopy (FT-IR) show the intensification of destructive hydrogenation reactions in the presence of water-soluble catalysts. According to the XRD and SEM-EDX results, the metal salts are thermally decomposed during the aquathermolysis process into the oxides of corresponding metals and are particularly sulfided by the sulfur-containing aquathermolysis products.

Study on Optical Energy Gap and the Thickness of Boron Doped Graphenic Carbon (B-GC) Film Prepared by Nanospray Method

Graphenic carbon (GC) provides a potential ability as photovoltaic material due to its tunable properties. Here, we investigate the optical energy gap and the thickness of B-GC material as a p-type in solar cell application. The GC was prepared from old charcoal powders of coconut shells by heating process at 400°C and B-GC powders were prepared by wet mixing method using boric acid as B atom source. B-GC films were then prepared by employing nebulizer as a nanospraying method. All samples were examined through various characterization techniques such as X-Ray Diffarction (XRD), SEM cross section, and UV-Vis spectroscopy. The amorphous characteristic of B-GC is confirmed by broad peaks in XRD patterns, similar to that of reduced graphene oxide (rGO). The present of B along with O and dominant C elements is determined by SEM-EDX result. The B dopants affect the optical bandgap energy (Eg) of GC as an intrinsic material. The thickness of B-GC films was found to be thinner than in a previous study that used a similar method but different equipment. The average thickness of B-GC films is in the range of 127 to 420 nm, followed by an increase in the deposition time for 5 to 20 s. Estimation of the Eg value indicated that B-GC has an energy gap around 2 eV, which is most suitable as a window layer in solar cell applications.

The effect of chicken eggshell (Gallus gallus domesticus) particle size as filler to polyester composite as motorcycle’s exhaust pipe cover material

This research was done to know the effect of chicken eggshell (Gallus gallus domesticus) powder particle size on unsaturated polyester resin mechanical properties. The eggshell was mashed and sifted to get the 50 mesh, 70 mesh, 90 mesh, 110 mesh, 130 mesh, 150 mesh, and 170 mesh particle size by using a ball mill. Then, the eggshell was mixed with an unsaturated polyester resin matrix with the ratio of 70:30 and methyl ethyl ketone peroxide (MEKP) catalyst as much as 1 % of the matrix mass. After that, it was pressed by using compression molding. The composite formed was characterized by Scanning Electron Microscopy Energy Dispersive X-ray (SEM EDX), Fourier Transform Infra-Red (FTIR), and X-Ray Diffraction (XRD). The physical properties of the composite were analyzed and the mechanical properties were tested. The SEM EDX result showed that the eggshell and composite were made up of Ca, C, and O, and the polyester was made up of C, O, and Si. The composite highest tensile strength and impact strength were at 150 mesh particle size of chicken eggshell powder which is 45.153 MPa and 9. 04 J/m2.

Conversion and syngas production of toluene as a biomass tar model compound in chemical looping reforming

The removal of tar is a main challenge for biomass gasification. In this paper, toluene was used as a tar model compound, and 6Ni, 4Ni2Cu and 4Ni2Fe were used as oxygen carriers (OCs). The chemical looping reforming (CLR) of toluene was studied at different temperatures and different steam/carbon molar ratios (S/C). Experimental results showed that the metal OC plays a dual-function of oxidation-catalysis for CLR of toluene. When using 6Ni, 4Ni2Cu and 4Ni2Fe as OC, the toluene conversions were 93.07%, 87.18% and 94.44%, respectively, at the S/C of 2.0 and the reaction temperature of 900 °C, and the syngas yields were 3.19 Nm3/kg, 3.10 Nm3/kg and 3.26 Nm3/kg, respectively. Meanwhile, 4Ni2Fe has the best carbon deposition resistance among the three OCs. The stable performance of 4Ni2Fe with high reactivity was demonstrated during 10 cyclic experiments with the temperature of 900 °C and at the S/C of 2.0. After 10 cycles, SEM-EDX and XRD results indicated that the 4Ni2Fe has satisfactory stability and regeneration performance. These results fully demonstrate that, among the three OCs, the 4Ni2Fe is the most ideal OC in the CLR of toluene.

A new visible-light driven photocatalytic PVDF-MoS2@WO3 membrane for clean water recovery from natural rubber wastewater

Photocatalytic membrane (PM) has been broadly used for industrial wastewater treatment. However, most developed photocatalytic materials are only responsive to UV-light irradiation. In this study, MoS2@WO3 composite was hydrothermally synthesized and added to PVDF membranes for rubber wastewater treatment. The diffuse reflectance spectra (DRS) results prove that the MoS2@WO3 composite is responsive to visible light irradiation with a 1.49 eV band gap. According to the SEM-EDX result, the MoS2@WO3 composite has been successfully embedded and evenly dispersed on the membrane surface and matrix. The addition of MoS2@WO3 increased the hydrophilicity of the membrane with the initial flux value up to 44.26 L·min−2·h−1 and 63.69 L·min−2·h−1 in dark and vis-light irradiation, respectively. The rejection values reached 97.04 %, 90.63 %, and 95.64 % for COD, TDS, and NH3-N, respectively, and showed excellent reusability after 5 recovery cycles upon vis-light irradiation. It has been proven that PVDF-MoS2@WO3 membrane shows the highest constant rate (k) values, 2.93 × 10−3 min−1 and 2.72 × 10−3 min−1 for COD and NH3-N, respectively. The scavenger analysis confirmed that *OH radical is the primary responsible species to organic pollutant degradation. All results have proven that MoS2@WO3 affects the membrane performance from the physical separation process through filtration and photocatalytic degradation mechanisms. Therefore, the PVDF-MoS2@WO3 photocatalytic membrane offers a promising potential to improve the performance of the existing rubber wastewater treatment.

In vitro release of aluminum from the geophagic clay "Chacco" in the Peruvian highlands: Chemical characterization and health risk assessment

In the altiplano zone of Latin America, "Chacco" is one of the clays widely consumed as part of geophagy. The objectives of the study were to chemically characterize "Chacco", determine the zero charge point, evaluate the release of aluminum in vitro, perform the kinetic study and evaluate the health risk. The results by ICP-OES showed that the elements with the highest concentration were Al, Ba, Ca, Fe, K, Mg, Mn, Na, Si, Sr, Ti and Zn. ATR-FTIR analysis showed the presence of Si-O (693 and 990 cm−1), Al-O (790 cm−1), Al-Al-OH bending vibration (912 cm−1), Si-H bond stretching (2100 to 2500 cm−1) and free -OH groups (3629 cm−1). SEM-EDX results indicate that Al is one of the main constituents of "Chacco" (7.35 wt%). The pHzpc of "Chacco" was 6.83. In the dissolution profiles, the highest Al release occurred at pH 6.8 and in intestinal juice simulated with pseudo-second order dissolution kinetics. The EDIAl and EWIAl were 20.24 and 142.66 respectively, comparing EWIAl with the PTWI established by JECFA (2 mg/kg bw), it is concluded that the weekly intake of "Chacco" represents an appreciable health risk. There are no reports of the carcinogenic factor of Al, so TRAl was not calculated.

Exploration on the role of different iron species in the remediation of As and Cd co-contamination by sewage sludge biochar.

Numerous studies have explored the adsorption of cadmium (Cd) and arsenic (As) by iron (Fe)-modified biochar, but few studies have examined in-depththe similarities and differences in the adsorption behavior of different iron types on Cd and As. In this study, sewage sludge biochar (BC) was co-pyrolyzed with self-made Fe minerals (magnetite, hematite, ferrihydrite, goethite, and schwertmannite) to treat Cd and As co-contaminated water. The adsorption of Cd and As on the Fe-modified biochar was further analyzed by adsorption kinetics, adsorption isotherms, and adsorption thermodynamics combined with a series of characterization experiments. Both SEM-EDX and XRD results confirmed the successful loading of iron minerals onto BC. Both adsorption kinetics and adsorption isotherms experiments showed that the adsorption of Cd and As by BC and the other five Fe-modified biochar was mainly controlled by chemical interactions. The results also indicated that goethite biochar (GtBC) was the most effective for the adsorption of Cd among the five Fe-modified biochar. Ferrihydrite biochar (FhBC) formed more diverse complexes, coupled with the relatively stronger electrons accepting ability, thus making it more effective for As adsorption than the others. Additionally, GtBC and hematite biochar (HmBC) were found effective for the adsorption of both Cd and As, whereas MBC was not found effective for either metal. Furthermore, combined with XPS results, the adsorption of Cd by the materials was mainly governed by Cd2+-π interactions, complexation precipitation, and co-precipitation, while oxidation reactions also existed for As.

The Effectiveness of Active Carbon Adsorbent of Cassava Peel (Manihot Esculenta Cranzts) in Reduce Level of Chromium Metal in Tannery Liquid Waste

This study aims to determine the characteristics, the effect of mass variation, the percentage of adsorption effectiveness of cassava peel activated carbon activated with 0.5 M HCl and activated with 0.5 M H2SO4 on the adsorption of Cr metal in leather tanning wastewater and its morphology. The subject of this research is the adsorbent of cassava peel before it is asctivated, activated by chloric acid 0,5 M, and activated by sulfuric acid 0,5 M. meanwhile the object of this research is the effectiviness of cassava peel adsorbeny in reduscing chromium metal content in tannery liquid waste. Cassava pell was carbonized at 500 oC for 1 hour. The cassava peel carbon was characterized according to SNI 06-3730-1995. The adsorption process is performed by batch method. Analysis was performed by Atomic Adsorption Spectrophotometer, PSA, and SEM-EDX. The result of the characterization of cassava peel carbon showed that the moisture content, ash content, adsorption capacity of I2 met SNI, meanwhile the carbon contenr and volatile matter conten did not met SNI. The adsorption efficiency of kromium metal is 95.97% for carbon before activated, 95.33% for carbon activated by chloroc acid, and 96.65% for carbon activated by sulfuric acid. The result of PSA size of cassava peel adsorbent before activated by chloric acid and sulfuric acid were 34.484 µm, 42.504 µm, and 37.059 µm respectively. Cassave peel adsorbent has a Langmuir adsorption type. The SEM-EDX result showed that the adsorbent from cassava peel had a dissimiliar pore shape

Structure, crystallization behavior and chemical stability analysis of Nd3+-basaltic glasses for immobilizing simulated trivalent actinides

The Nd3+-basaltic glass was prepared by melt-heat treatment method using Nd3+ to simulate trivalent actinides. The structure, thermal stability and leaching characteristics of basaltic glass with different contents of Nd2O3 were investigated. XRD and SEM-EDX results show that the simulated waste loading of Nd2O3 in basaltic glass can be up to ∼30 wt.%, and oxy-silicate apatite (Ca2Nd8(SiO4)6O2) precipitates when Nd2O3 content reaches 32 wt.%. Raman results indicate that the addition of Nd2O3 breaks some of Si-O-Si bond, but overall there is not much effect on the glass network structure. DSC results show the Tg of the glasses increases and the thermal stability first increases and then decreases with the increase of Nd2O3 content. The leaching resistance of samples was evaluated by the ASTM Product Consistency Test (PCT) Method, which shows that all the samples have good leaching resistance. Among them, the standard mass loss of Na is the greatest after 28 days. The NLNd is 4∼5 orders of magnitude lower than other elements.

Bioimmobilization and transformation of chromium and cadmium in the fungi-microalgae symbiotic system

Microalgae and fungi in the fungi-microalgae symbiotic system(FMSS) can solve the problems of deep purification of heavy metals in wastewater and harvesting of microalgae cell by synergistic interaction. Therefore, it is of great significance to use the FMSS for remediation of heavy metal pollution. However, at present, the immobilization and transformation mechanism of heavy metals in the FMSS is not clear, which limits the development and industrial application of the FMSS with high adsorption performance, high selectivity, and high tolerance. In this study, the FMSS constructed using Aspergillus funigatus and Synechocystis sp. PCC6803, was used as the research object to explore heavy metal adsorption performance. Under optimal conditions, the adsorption efficiencies of Cd(II) and Cr(VI) were as high as 90.02% and 80.03%, respectively. The adsorption process was controlled by both internal and external diffusion. Extracellular absorption was dominant, and intracellular absorption was secondary. XRD, XPS, SEM-EDX and TEM-EDX results revealed that ionic crystals and precipitates (Cd(OH)2, CdCO3, calcium oxalate crystals, Cr(OH)3, Cr2O3, and CrCl3) were formed after adsorption. The adsorption of Cr(VI) involved the reduction of Cr(VI). Functional groups, such as amino, carboxyl, aldehyde, and ether groups, on the cell surface also interact with heavy metal ions. To summarize, by constructing the FMSS, optimizing the symbiosis conditions, exploring the adsorption and accumulation rules of Cd(II) and Cr(VI) inside and outside the cells in the system, and revealing the molecular response mechanism, we were able to establish a theoretical basis for further understanding the interaction between the FMSS and heavy metals.