scholarly journals Characterization of ultraviolet-modified biochar from different feedstocks for enhanced removal of hexavalent chromium from water

2019 ◽  
Vol 79 (9) ◽  
pp. 1705-1716 ◽  
Author(s):  
Zhongya Peng ◽  
Xiaomei Liu ◽  
Hongkun Chen ◽  
Qinglong Liu ◽  
Jingchun Tang
Keyword(s):  
Functional Groups ◽  
Hexavalent Chromium ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Environmental Remediation ◽  
Low Cost ◽  
Surface Areas ◽  
Modified Biochar ◽  
Sorption Ability ◽  
Novel Material

Abstract Biochars produced from different feedstocks via pyrolytic carbonization and ultraviolet (UV) modification were used as alternative adsorbents for aqueous hexavalent chromium (Cr(VI)) remediation. Structural and morphological analysis showed that UV irradiation increased the surface area of biochar and added a large amount of oxygen-containing functional groups on the biochar's surface, resulting in about 2–5 times increase of Cr(VI) removing capacity (14.39–20.04 mg/g) compared to that of unmodified biochars (3.60–8.43 mg/g). The sorption ability among different feedstocks after modification was as follows: corn stack > sawdust > wheat straw. The adsorption kinetics and adsorption isotherm data agreed well with the pseudo-second-order model and Freundlich model, respectively. Experimental and modeling results suggested that the oxygen-containing functional groups and surface areas of biochars were notably increased after UV irradiation, which was mainly governed by surface complexation. X-ray photoelectron spectroscopy analysis showed that reduction occurred during Cr(VI) adsorption. In addition, UV irradiation significantly increased the concentration of dissolved organic matter (DOM) in biochars. The collected outcomes showed that UV-modified biochar was a good material for the removal of hexavalent chromium from aqueous medium. The excellent adsorption capacity, environmental-friendly and low cost properties made the novel material an auspicious candidate for environmental remediation.

scholarly journals Risk Evaluation of Pyrolyzed Biochar from Multiple Wastes

2019 ◽  
Vol 2019 ◽  
pp. 1-28 ◽  
Author(s):  
Shem M. Ndirangu ◽  
Yanyan Liu ◽  
Kai Xu ◽  
Shaoxian Song
Keyword(s):  
Functional Groups ◽  
Risk Evaluation ◽  
Low Cost ◽  
Risk Index ◽  
Potential Ecological Risk ◽  
Pyrolysis Process ◽  
Air Oxidation ◽  
Net Benefit ◽  
Modified Biochar ◽  
Contaminated Food

This paper aims at demonstrating the significance of biochar risk evaluation and reviewing risk evaluation from the aspects of pyrolysis process, feedstock, and sources of hazards in biochar and their potential effects and the methods used in risk evaluation. Feedstock properties and the resultant biochar produced at different pyrolysis process influence their chemical, physical, and structural properties, which are vital in understanding the functionality of biochar. Biochar use has been linked to some risks in soil application such as biochar being toxic, facilitating GHGs emission, suppression of the effectiveness of pesticides, and effects on soil microbes. These potential risks originate from feedstock, contaminated feedstock, and pyrolysis conditions that favor the creation of characteristics and functional groups of this nature. These toxic compounds formed pose a threat to human health through the food chain. Determination of toxicity levels is a first step in the risk management of toxic biochar. Various sorption methods of biochar utilized low-cost adsorbents, engineered surface functional groups, and nZVI modified biochars. The mechanisms of organic compound removal was through sorption, enhanced sorption, modified biochar, postpyrolysis thermal air oxidation and that of PFRs degradation was through activation, photoactive functional groups, magnetization, and hydrothermal synthesis. Emissions of GHGs in soils amended with biochar emanated through physical and biotic mediated mechanisms. BCNs have a significance in reducing the health quotient indices for PTEs risk contamination by suppressing cancer risk arising from consumption of contaminated food. The degree of environmental risk assessment of HM pollution in biomass and biochars has been determined by using potential ecological risk index and RAC while organic contaminant degradation by EPFRs was considered when assessing the environmental roles of biochar in regulating the fate of contaminants removal. The magnitude of technologies’ net benefit must be considered in relation to the associated risks.

scholarly journals Catalytic Reduction of Hexavalent Chromium Using Iron/Palladium Bimetallic Nanoparticle-Assembled Filter Paper

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1183 ◽  
Author(s):  
Daniel Shi ◽  
Zhijun Ouyang ◽  
Yili Zhao ◽  
Jie Xiong ◽  
Xiangyang Shi
Keyword(s):  
Hexavalent Chromium ◽  
Filter Paper ◽  
Environmental Remediation ◽  
Bimetallic Nanoparticles ◽  
Catalytic Reduction ◽  
Low Cost ◽  
Bimetallic Nanoparticle ◽  
Amine Groups ◽  
Positively Charged ◽  
Iron Palladium

Iron/palladium bimetallic nanoparticles (Fe/Pd NPs) are important catalytic materials for the field of environmental remediation. In the present study, filter paper was employed as a substrate for the assembly of Fe/Pd NPs and further applied for the catalytic conversion of hexavalent chromium Cr(VI) toward trivalent Cr(III). First, a filter paper with negative charge was assembled with a layer of positively charged polyethylenimine (PEI) through electrostatic interaction; then, the abundant amine groups of PEI were used to complex Fe(III) ions, followed by reduction via sodium borohydride to produce an Fe NP-assembled filter paper. Thereafter, the Fe/Pd NPs were produced by the reduction of PdCl42− through Fe NPs. The prepared filter paper assembled with Fe/Pd NPs with a mean diameter of 10.1 nm was characterized by various techniques. The Fe/Pd NP-assembled filter paper possesses powerful catalytic activity and can be used to transform Cr(VI) to Cr(III). With its low cost, high sustainability, and convenient industrialization potential, the developed approach may be extended to produce other bimetallic NP-immobilized filter paper for different environmental remediation applications.

scholarly journals Process Optimization by a Response Surface Methodology for Adsorption of Congo Red Dye onto Exfoliated Graphite-Decorated MnFe2O4 Nanocomposite: The Pivotal Role of Surface Chemistry

Processes ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 305 ◽  
Author(s):  
Van Thinh Pham ◽  
Hong-Tham T. Nguyen ◽  
Duyen Thi Cam Nguyen ◽  
Hanh T. N. Le ◽  
Thuong Thi Nguyen ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Congo Red ◽  
Low Cost ◽  
Chemical Oxidation ◽  
Exfoliated Graphite ◽  
Surface Functional Groups ◽  
Total Base

Natural graphite, a locally available, eco-friendly, and low-cost carbonaceous source, can be easily transformed into exfoliated graphite (EG) with many surface functional groups via a chemical oxidation route. Combination between EG and magnetic MnFe2O4 is a promising strategy to create a hybrid kind of nanocomposite (EG@MnFe2O4) for the efficient adsorptive removal of Congo red (CR) dye from water. Here, we reported the facile synthesis and characterization of chemical bonds of EG@MnFe2O4 using several techniques such as Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). In particular, the quantity method by Boehm titration was employed to identify the content of functional groups: Carboxylic acid (0.044 mmol/g), phenol (0.032 mmol/g), lactone (0.020 mmol/g), and total base (0.0156 mmol/g) on the surface of EG@MnFe2O4. Through the response surface methodology-optimized models, we found a clear difference in the adsorption capacity between EG-decorated MnFe2O4 (62.0 mg/g) and MnFe2O4 without EG decoration (11.1 mg/g). This result was also interpreted via a proposed mechanism to elucidate the contribution of surface functional groups of EG@MnFe2O4 to adsorption efficiency towards CR dye.

scholarly journals Effects of Ionic Liquid and Biomass Sources on Carbon Nanotube Physical and Electrochemical Properties

2021 ◽  
Vol 13 (5) ◽  
pp. 2977
Author(s):  
Kudzai Mugadza ◽  
Annegret Stark ◽  
Patrick G. Ndungu ◽  
Vincent O. Nyamori
Keyword(s):  
Ionic Liquid ◽  
Electrochemical Properties ◽  
Photoelectron Spectroscopy ◽  
Nitrogen Doping ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
Doping Content ◽  
Ongoing Research ◽  
Surface Areas ◽  
Pyridinic Nitrogen

The ongoing research toward meeting global energy demands requires novel materials from abundant renewable resources. This work involves an investigation on nitrogen-doped carbon nanotubes (N-CNTs) synthesized from relatively low-cost and readily available biomass as carbon precursors and their use as electrodes for supercapacitors. The influence of the ionic liquid 1-butyl-3-methylimidazolium chloride, or its combination with either sugarcane bagasse or cellulose (IL-CNTs, ILBag-CNTs, and ILCel-CNTs, respectively), in the synthesis of N-CNTs and the resultant effect on their physical and electrochemical properties was studied. Systematic characterizations of the N-CNTs employing transmission electron microscopy (TEM), thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), elemental analysis, nitrogen sorption analysis, cyclic voltammetry, and electrochemical impedance spectroscopy were performed. TEM data analysis showed that the mean outer diameters decreased, in the order of IL-CNTs > ILBag-CNTs > ILCel-CNTs. The N-CNTs possess only pyridinic and pyrrolic nitrogen-doping moieties. The pyridinic nitrogen-doping content is lowest in IL-CNTs and highest in ILCel-CNTs. The N-CNTs are mesoporous with surface areas in the range of 21–52 m2 g−1. The ILCel-CNTs had the highest specific capacitance of 30 F g−1, while IL-CNTs has the least, 10 F g−1. The source of biomass is beneficial for tuning physicochemical properties such as the size and surface areas of N-CNTs, the pyridinic nitrogen-doping content, and ultimately capacitance, leading to materials with excellent properties for electrochemical applications.

scholarly journals An exploratory study on low-concentration hexavalent chromium adsorption by Fe(III)-cross-linked chitosan beads

2017 ◽  
Vol 4 (11) ◽  
pp. 170905 ◽  
Author(s):  
Yaoguo Wu ◽  
Yuanjing Zhang ◽  
Jin Qian ◽  
Xu Xin ◽  
Sihai Hu ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Functional Groups ◽  
Hexavalent Chromium ◽  
Photoelectron Spectroscopy ◽  
Limiting Factor ◽  
Good Prospect ◽  
Chitosan Beads ◽  
Low Concentration ◽  
Adsorption Mechanisms ◽  
Ph Range

In this study, Fe(III)-cross-linked chitosan beads (Fe(III)-CBs) were synthesized and employed to explore the characteristics and primary mechanism of their hexavalent chromium (Cr(VI)) adsorption under low concentration Cr(VI) (less than 20.0 mg l −1 ) and a pH range from 2.0 to 8.0. Batch tests were conducted to determine the Cr(VI) adsorption capacity and kinetics, and the effects of pH and temperature on the adsorption under low concentration Cr(VI) and a pH range from 2.0 to 8.0. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were employed to explore the characteristics of Fe(III)-CBs and their Cr(VI) adsorption mechanisms. The results show that, unlike the adsorption of other absorbents, the Cr(VI) adsorption was efficient in a wide pH range from 2.0 to 6.0, and well described by the pseudo-first-order model and the Langmuir–Freundlich isotherm model. The capacity of Cr(VI) adsorption by Fe(III)-CBs was as high as 166.3 mg g −1 under temperature 25°C and pH 6.0. The desorption test was also carried out by 0.1 mol l −1 NaOH solution for Fe(III)-CBs regeneration. It was found that Fe(III)-CBs could be re-used for five adsorption–desorption cycles without significant decrease in Cr(VI) adsorption capacity. Ion exchange was confirmed between functional groups (i.e. amino group) and Cr(VI) anions (i.e. CrO 4 2 − ). The amino-like functional groups played a key role in Cr(VI) distribution on the Fe(III)-CBs surface; Cr(VI) adsorbed on Fe(III)-CBs was partially reduced to Cr(III) with alcoholic group served as electron donor, and then formed another rate-limiting factor. So, Fe(III)-CBs has a good prospect in purifying low concentration Cr(VI) water with a pH range from 2.0 to 6.0.

scholarly journals Synthesis and catalytic properties of a novel copper- and manganese-substituted cerium dioxide for benzene remediation

2020 ◽  
pp. 174751982094588
Author(s):  
Jae Hwan Yang ◽  
Jeong Hyun You
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Environmental Remediation ◽  
Surface Defects ◽  
Superior Performance ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Areas ◽  
Transmission Electron

Catalysts based on inexpensive and abundant transition metals are necessary for effective environmental remediation. In this study, a series of CuMn-CeO2 catalysts is synthesized by a simple coprecipitation method. The properties of the as-prepared catalysts are characterized by X-ray diffraction, Brunauer–Emmett–Teller analysis, scanning electron microscopy–energy-dispersive spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The introduction of dopants results in rougher surfaces with greater surface areas and pore volumes as well as more surface defects. Furthermore, the dopant-added catalysts exhibit higher activities for benzene oxidation, as the temperature required for 90% benzene removal with Cu4Mn1-CeO2 (656 K) was 231 K lower than that required with CeO2. The superior performance of the dopant-added CeO2 catalyst is attributed to the generation of defect-rich surfaces due to the isomorphous substitution of Cu and Mn in the crystal lattice of CeO2.

scholarly journals Efficient Removal of Cd (II) From Aqueous Solution By Chitosan Modified Kiwi Branch Biochar

2021 ◽  
Author(s):  
Yuehui Tan ◽  
Xirui Wan ◽  
Xue Ni ◽  
Le Wang ◽  
Ting Zhou ◽  
...  
Keyword(s):  
Functional Groups ◽  
Low Cost ◽  
Maximum Adsorption Capacity ◽  
Surface Functional Groups ◽  
Order Model ◽  
Efficient Removal ◽  
Adsorption Ability ◽  
Modified Biochar ◽  
Pseudo Second Order ◽  
Interaction Surface

Abstract A novel chitosan-modified kiwi branch biochar (CHKB) was successfully fabricated as cut-price modified biochar to remove Cd (II) from wastewater. Characterization experiments with SEM-EDS, FTIR and XPS suggested that CHKB had more cations and surface functional groups compared with the original kiwi biochar (KB). The adsorption experiment results of Cd (II) on CHKB showed that the adsorption isotherms can be described best by the Langmuir model and that the pseudo-second-order model fits the Cd (II) adsorption kinetics well, indicating that the process was monolayer and controlled by chemisorption. CHKB exhibited the Langmuir maximum adsorption capacity of Cd (II) (126.58 mg g-1), however, that of KB is only 4.26 mg g-1. The adsorption ability of CHKB was improved by the increase of the surface area and abundant surface functional groups (-OH, -NH, C=O and so on). And the cation exchange, electrostatic interaction, surface complexation and precipitation were main mechanisms in the sorption of Cd (II) on CHKB. In addition, CHKB can be regenerated and reused for Cd (II) sorption by the eluent of EDTA-2Na. Excellent adsorption performance, low-cost, and environmental-friendly made CHKB become the fantastic adsorbent to remove Cd (II) in wastewater.

Performance and Mechanism for Fluoride Removal in Groundwater with Calcium Modified Biochar from Peanut Shell

2020 ◽  
Vol 12 (4) ◽  
pp. 492-501 ◽  
Author(s):  
Rui-Ling Zhang ◽  
Jing Xu ◽  
Lei Gao ◽  
Zhe Wang ◽  
Bo Wang ◽  
...  
Keyword(s):  
Calcium Chloride ◽  
Functional Groups ◽  
Removal Efficiency ◽  
Low Cost ◽  
Calcium Content ◽  
Fluoride Removal ◽  
Peanut Shell ◽  
Modified Biochar ◽  
Pseudo Second Order ◽  
Safe Technique

Fluoride in groundwater poses a great risk to humans. Biochar is an effective and environmental-friendly adsorbent for fluoride removal. The objectives of this study were to develop a calcium modified biochar derived from peanut shell and to study its mechanism in the adsorptive removal of fluoride. For these purposes, biochar was prepared using three different techniques. No. 1 biochar was prepared by direct carbonization, No. 2 biochar was modifiied with 30% calcium chloride solution before carbonization, and No. 3 biochar was modified with 30% calcium chloride following carbonization. The No. 2 biochar clearly showed the highest percentage fluoride removal (92.1%) and the fluoride removal efficiency improved by 30%–60% compared with other techniques. The adsorption isotherms and kinetics of the biochar modified with calcium were best described by the Langmuir and pseudo-second-order model, respectively. Based on the calcium content from the energy spectrum, calcium was well loaded onto the biochar. Calcium detached experiments indicated the loaded calcium was the main method for fluoride removal of No. 2 biochar, the adsorption mechanism was clearly demonstrated through the changes of morphology and group during adsorption. Fourier transform infrared spectroscopic (FTIR) analyses indicated the highest fluoride removal efficiency of No. 2 biochar was due to cleavage and structural change in many functional groups. But only C–H was involved in No. 3 biochar fluoride removal process. The good performance of No. 2 biochar for de-fluoridation was due to the calcium stably loaded onto the biochar and many of the changed functional groups there. Biochar modified with calcium before carbonization is an efficient, low-cost, safe technique for de-fluoridation.

scholarly journals Photocatalytic reduction of graphene oxide with cuprous oxide film under UV-vis irradiation

2020 ◽  
Vol 59 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Yao Wang ◽  
Jianqing Feng ◽  
Lihua Jin ◽  
Chengshan Li
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Photocatalytic Reduction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Reduced Graphene ◽  
Reduction Efficiency ◽  
Metal Organic ◽  
Reduction Effect

AbstractWe have grown Cu2O films by different routes including self-oxidation and metal-organic deposition (MOD). The reduction efficiency of Cu2O films on graphene oxide (GO) synthesized by modified Hummer’s method has been studied. Surface morphology and chemical state of as-prepared Cu2O film and GO sheets reduced at different conditions have also been investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). Results show that self-oxidation Cu2O film is more effective on phtocatalytic reduction of GO than MOD-Cu2O film. Moreover, reduction effect of self-oxidation Cu2O film to GO is comparable to that of environmental-friendly reducing agent of vitamin C. The present results offer a potentially eco-friendly and low-cost approach for the manufacture of reduced graphene oxide (RGO) by photocatalytic reduction.

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