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EARTH 2019-Green Technologies for Resources and Materials Recycling
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EARTH 2019-Green Technologies for Resources and Materials Recycling

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Sustainable Materials".

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 51273

Special Issue Editor

Prof. Dr. Ji Whan Ahn

E-Mail Website
Guest Editor
Korea Institute of Geoscience and Mineral Resources, Korea
Interests: mineral carbonation; CO2 utilization; recycling technologies of industrial wastes; papers and diapers; green cement and waste-water treatment
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The 15th EARTH Symposium will offer all participants knowledge of the latest advances in waste recycling and management, including separating valuable materials from waste, waste treatment and minimization, recovering energy from waste, wastewater treatment, environmental impact assessment, metals recycling, environmental law and regulation, and other important topics related to resources and materials recycling.

a. Focus: This Special Issue focuses on the introduction of green technologies for resources and materials recycling throughout East Asia (Korea, Japan, Taiwan, China, and Thailand).

b. Scope: The notable level of urbanization throughout the world is accompanied by the exponential increase in power demand and limited resources. There are growing pressures and challenges from issues such as climate change, water scarcity, GHG emissions, increasing demand for energy and land loss, etc. We are determined to protect the planet from degradation through sustainable consumption and protection by managing its natural resources. Therefore, recycling is the best option for preventing a lack of resources for the needs of future generations.

We are especially interested in the topics listed below:

  • Resources processing (comminution/separation)
  • Hydrometallurgy (leaching/purification separation/electrowinning)
  • Pyrometallurgy (thermal pretreatment/smelting)
  • Organic-inorganic material processing (high-purity/powder/alloy)
  • Mine waste (hazardous matter removal/ recovery of valuables)
  • Waste recycling and management (separating valuable materials from waste/ waste minimization, recovering energy from waste
  • Sustainability
  • Metal recycling technologies/ recycling policies
  • Environmental impact assessment, environmental laws, and regulations

c. Purpose of the Special Issue: The purpose of this Special Issue is to introduce the new recycling technology trends, new developments, and advanced techniques in the valuable recycling system of waste management. Therefore, the scope and aim for this Special Issue are to introduce recent research on resources and advanced recycling technologies.

Prof. Dr. Ji Whan Ahn
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • resource processing
  • leaching
  • purification separation
  • electrowinning, green technologies
  • resource recycling
  • recycling policies
  • sustainability

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Published Papers (12 papers)

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Editorial

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9 pages, 1412 KiB  
Editorial
An Integrative Approach to International Technology Transfer for Recycling Vietnam Coal Ash with Consideration of the Technological, Legal, and Network Perspectives
by Jongyeol Lee, Taeyoon Kim, Mina Sung, Hong Ha Thi Vu, Kyung Nam Shin and Ji Whan Ahn
Sustainability 2020, 12(3), 771; https://doi.org/10.3390/su12030771 - 21 Jan 2020
Cited by 5 | Viewed by 2993
Abstract
The rapid economic growth of Vietnam has increased the amount of coal ash waste during electricity generation from coal-fired thermal power plants. This waste is being dumped even though the capacity of dumping sites will not be sufficient in the future. Accordingly, Korean [...] Read more.
The rapid economic growth of Vietnam has increased the amount of coal ash waste during electricity generation from coal-fired thermal power plants. This waste is being dumped even though the capacity of dumping sites will not be sufficient in the future. Accordingly, Korean technologies of recycling ashes, modifying them into a valuable product, and fixing carbon dioxide via carbon mineralization, can be an alternative to dumping. In this study, we aimed to investigate the feasibility of deploying carbon mineralization technology to Vietnam while considering technological, legal, and network perspectives. The material properties of coal ash and the applicability of coal ash recycling technology were briefly investigated in Vietnam. Legislation has progressed, focusing on recycling coal ash as a building material, with supportive measures on investment and international cooperation. Meanwhile, a bilateral network between Vietnam and the Republic of Korea at the institutional and governmental levels strengthened the implementation of practical technology cooperation. In conclusion, we considered various perspectives in terms of the technology transfer of recycling coal ash. This technology transfer model can contribute to enhancing the possibility of successful technology cooperation for solving the environmental problems of coal ash. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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Research

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12 pages, 1018 KiB  
Communication
A Study on the Trend of Domestic Waste Generation and the Recognition of Recycling Priorities in Korea
by Seok-ho Jung, Mee-hye Lee, Seong-ho Lee and Ji Whan Ahn
Sustainability 2021, 13(4), 1732; https://doi.org/10.3390/su13041732 - 5 Feb 2021
Cited by 5 | Viewed by 4537
Abstract
In September 2015, the United Nations included ‘sustainable consumption and production’ as part of its 12th goal of sustainable development. The EU announced its Circular Economic Package in December 2015 to move from the existing linear economic structure to the net environmental system. [...] Read more.
In September 2015, the United Nations included ‘sustainable consumption and production’ as part of its 12th goal of sustainable development. The EU announced its Circular Economic Package in December 2015 to move from the existing linear economic structure to the net environmental system. Recycling of household waste has become more significant as a circular economic policy has been implemented to reflow waste into the economy through recycling worldwide. In this study, Korea’s household waste generation for 20 years from 1998 to 2017 was analyzed through statistical techniques. Waste generation tended to increase in the order of plastics and cans, and papers tended to decrease. The amount of bottle wastes has been on the decline after increasing. A questionnaire survey on recycling priority was conducted on 261 people, including participants in the EARTH-2019 recycling experience hall, using the analytic hierarchy process (AHP) technique. According to the survey, the recycling priorities of six types of household waste are (first) plastic, (second) cans, viny, scrap metals, (third) paper, and (fourth) bottles. Statistical analysis of mid- to long-term household waste generation and AHP-based household waste recycling priority survey results can be used as basic data, such as environmental analysis in Korea’s recycling-related policies and research. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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12 pages, 2054 KiB  
Communication
Analysis of the State of the Art of International Policies and Projects on CCU for Climate Change Mitigation with a Focus on the Cases in Korea
by Seok-ho Jung, Seong-ho Lee, Jihee Min, Mee-hye Lee and Ji Whan Ahn
Sustainability 2021, 13(1), 19; https://doi.org/10.3390/su13010019 - 22 Dec 2020
Cited by 7 | Viewed by 4312
Abstract
In 2016, the Korean government selected carbon capture and utilization (CCU) as one of the national strategic projects and presented a detailed roadmap to reduce greenhouse gas emissions and to create new climate industries through early demonstration of CCU technology. The Korean government [...] Read more.
In 2016, the Korean government selected carbon capture and utilization (CCU) as one of the national strategic projects and presented a detailed roadmap to reduce greenhouse gas emissions and to create new climate industries through early demonstration of CCU technology. The Korean government also established the 2030 Greenhouse Gas Reduction Roadmap in 2016 and included carbon capture, utilization, and storage (CCUS) technology in the new energy industry sector as a CCU technology. The Korean government recognizes the importance of CCUS technology as a mid- to long-term measure to reduce greenhouse gas emissions and implements policies related to technological development. The United States (U.S.), Germany, and China also expect CCUS technology to play a major role in reducing greenhouse gases in the industrial sector in terms of climate and energy policy. This study analyzed the CCU-related policies and technological trends in the U.S., Germany, and China, including major climate and energy plans, driving roadmaps, some government-led projects, and institutional support systems. This work also statistically analyzed 447 CCU and CCUS projects in Korea between 2010 and 2017. It is expected to contribute to responding to climate change, promoting domestic greenhouse gas reduction, and creating future growth engines, as well as to be used as basic data for establishing CCU-related policies in Korea. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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14 pages, 3875 KiB  
Article
Towards Improved Circular Economy and Resource Security in South Korea
by Kyounga Lee and Jongmun Cha
Sustainability 2021, 13(1), 17; https://doi.org/10.3390/su13010017 - 22 Dec 2020
Cited by 26 | Viewed by 10041
Abstract
This study explores the importance of critical raw materials and minerals by analyzing the Republic of Korea’s recent circular economy and resource security policy. Raw materials and rare metals are becoming increasingly significant to the Korean economy because the country is currently shifting [...] Read more.
This study explores the importance of critical raw materials and minerals by analyzing the Republic of Korea’s recent circular economy and resource security policy. Raw materials and rare metals are becoming increasingly significant to the Korean economy because the country is currently shifting away from fossil fuels and nuclear power towards renewable energy resources as well as transforming its industries towards decarbonization, digitization, and automation. Korea is a resource-poor country and is heavily dependent on imported minerals and rare earths, which are essential for its economy and new industry. Responding to these challenges and concerns, Korea is moving towards a sustainable circular economy and achieving greater resource security. Despite certain limitations, this transition would ultimately contribute in preparing Korea for current and future challenges in the areas of critical raw materials and minerals. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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13 pages, 3763 KiB  
Article
Use of Calcite Mud from Paper Factories in Phosphorus Treatment
by Hong Ha Thi Vu, Mohd Danish Khan, Van Tan Tran, Dang Viet Quang, Van-Duong Dao, Seongho Lee, Ji Whan Ahn and Seok-ho Jung
Sustainability 2020, 12(15), 5982; https://doi.org/10.3390/su12155982 - 24 Jul 2020
Cited by 5 | Viewed by 2479
Abstract
To use calcite mud waste generated from the paper production process, calcite mud was treated by calcination and then applied as a sorbent agent to remove phosphorus from an aqueous solution. The pre-treatment muds were characterized by scanning electron microscopy, Fourier transform infrared [...] Read more.
To use calcite mud waste generated from the paper production process, calcite mud was treated by calcination and then applied as a sorbent agent to remove phosphorus from an aqueous solution. The pre-treatment muds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effects of calcite mud with different calcination temperatures on phosphorus removal were investigated. Different sorbent dosages, contact times, and initial phosphorus concentration conditions were also studied to understand the phosphorus removal mechanism. The results show that phosphorus removal efficiency was increased by increasing the calcination temperature of the mud. The phosphorus removal efficiency over 10 min increased by 35%, 82%, 98%, and 100% with 4.5, 6.75, 9.0, and 11.25 mg, respectively, of calcite mud calcined at 1000 °C. However, the efficiency decreased as initial phosphorus concentration increased. To study the phosphorus removal trend, the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models were used. The Langmuir and Freundlich isotherm models were also used to further investigate the phosphorus adsorption mechanism characteristics of the calcite mud. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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10 pages, 2780 KiB  
Communication
Synthesis, Characterization and Mechanism Study of Green Aragonite Crystals from Waste Biomaterials as Calcium Supplement
by Lulit Habte, Mohd Danish Khan, Natnael Shiferaw, Adeeba Farooq, Mee-hye Lee, Seok-ho Jung and Ji Whan Ahn
Sustainability 2020, 12(12), 5062; https://doi.org/10.3390/su12125062 - 22 Jun 2020
Cited by 15 | Viewed by 4398
Abstract
In present work, environmentally benign green aragonite crystals were synthesized from waste chicken eggshells and bivalve seashells through a simple and low-cost wet carbonation method. This method involves a constant stirring of calcium oxide slurry and magnesium chloride suspension in aqueous solution with [...] Read more.
In present work, environmentally benign green aragonite crystals were synthesized from waste chicken eggshells and bivalve seashells through a simple and low-cost wet carbonation method. This method involves a constant stirring of calcium oxide slurry and magnesium chloride suspension in aqueous solution with constraint carbon dioxide injection at 80 °C. The physicochemical properties of the synthesized aragonite were further compared with the aragonite synthesized from commercial calcium oxide. The morphological analysis, such as acicular shape and optimum aspect ratio (~21), were confirmed by scanning electron microscopy. The average crystal size (10–30 µm) and specific surface area (2–18 m2 g−1) were determined by particle size and Brunauer–Emmett–Teller analysis, respectively. Moreover, a schematic crystal growth mechanism was proposed to demonstrate the genesis and progression of aragonite crystal. Green aragonite can bridge the void for numerous applications and holds the potential for the commercial-scale synthesis with eggshells and bivalve seashells as low-cost precursors. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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13 pages, 5339 KiB  
Article
Separation of Cerium Oxide Abrasive and Glass Powder in an Abrasive-Glass Polishing Waste by Means of Liquid–Liquid–Powder Extraction Method for Recovery: A Comparison of Using a Cationic and an Anionic Surfactant Collector
by Li-Pang Wang, Yan-Jhang Chen, Yun-Chen Tso, Chia-Feng Sheng, Josiane Ponou, Mingyin Kou, Heng Zhou and Wei-Sheng Chen
Sustainability 2020, 12(11), 4662; https://doi.org/10.3390/su12114662 - 8 Jun 2020
Cited by 4 | Viewed by 3291
Abstract
Applying a cerium oxide abrasive to polish glass components generates a polishing waste containing the cerium oxide abrasive and the glass powder produced during polishing. This research applied the liquid–liquid–powder extraction method to separate the cerium oxide abrasive and the polished glass powder [...] Read more.
Applying a cerium oxide abrasive to polish glass components generates a polishing waste containing the cerium oxide abrasive and the glass powder produced during polishing. This research applied the liquid–liquid–powder extraction method to separate the cerium oxide abrasive and the polished glass powder in an abrasive-glass polishing waste for recovering the cerium oxide abrasive. Two liquids of isooctane and water were utilized. The effectiveness of using a cationic and an anionic surfactant collector, i.e., dodecylamine acetate (DAA) and sodium oleate (NaOL), respectively, in improving their extraction and separation was investigated and compared. The results indicated that NaOL addition could improve the mutual separation of cerium oxide abrasive and glass powder but DAA could not, because the former could selectively improve the extraction of cerium oxide abrasive from the water phase to isooctane phase whereas the latter could improve that of both powders. Optimal separation for the cerium oxide abrasive and the polished glass powder in an abrasive-glass polishing waste were achieved by adding NaOL of 7.5 kg/ton at pH 7; the content of cerium oxide abrasive in the solid recovered from the isooctane phase was 96.4% with a recovery of 88.1%. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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15 pages, 7137 KiB  
Article
Utilization of Basic Oxygen Furnace Slag in Geopolymeric Coating for Passive Radiative Cooling Application
by Chia-Ho Wu, Chih-Hong Huang, Yeou-Fong Li, Wei-Hao Lee and Ta-Wui Cheng
Sustainability 2020, 12(10), 3967; https://doi.org/10.3390/su12103967 - 12 May 2020
Cited by 6 | Viewed by 2744
Abstract
Basic oxygen furnace slag (BOFs) is difficult to reutilize because it contains excessive free lime, and thus causes serious expansion. For this reason, how to reuse BOF slag has turned out to be an imperative issue in order to meet the concept of [...] Read more.
Basic oxygen furnace slag (BOFs) is difficult to reutilize because it contains excessive free lime, and thus causes serious expansion. For this reason, how to reuse BOF slag has turned out to be an imperative issue in order to meet the concept of a circular economy. The key intention of this research work is to develop a new way to reutilize BOF slag, which due to its high emissivity in the 8–13 µm wavelength range, can be used as a sustainable, passive radiative cooling material. Passive radiative cooling, without the consumption of any energy, achieves the cooling of a surface by reflecting the sunlight and radiating the heat throughout the outer space (not absorbed by the atmosphere). BOF slag is used as a radiative cooling material in geopolymeric coating. This coating possesses an emissivity of 0.95 within the range of 8–13 µm and also has high conductivity, but its gray appearance absorbs too much heat. Therefore, by improving the situation through a double-layer structure, a temperature drop of 5.9 °C was reached compared to non-coated concrete under simulated sunlight, simultaneously with a low heating rate and high cooling rate. Besides, the binding strength between the geopolymeric coating and Portland cement concrete is comparable to two commercial organic paints. It is highly probable that the utilization of BOF slag in geopolymeric coating is energy saving and also feasible for passive radiative cooling applications. Hence, it can greatly decrease indoor temperature and improve the comfort of people living in buildings. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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10 pages, 3282 KiB  
Article
Recovery of Gallium from Simulated GaAs Waste Etching Solutions by Solvent Extraction
by Wei-Sheng Chen, Ko-Wei Tien, Li-Pang Wang, Cheng-Han Lee and Yi-Fan Chung
Sustainability 2020, 12(5), 1765; https://doi.org/10.3390/su12051765 - 27 Feb 2020
Cited by 6 | Viewed by 2977
Abstract
Gallium arsenide is used in semiconductor industries worldwide. Numerous waste etching solutions are produced during the processes of GaAs wafer production. Therefore, a complete and eco-friendly technology should be established to recover gallium as a gallium chloride solution and remove arsenic ion from [...] Read more.
Gallium arsenide is used in semiconductor industries worldwide. Numerous waste etching solutions are produced during the processes of GaAs wafer production. Therefore, a complete and eco-friendly technology should be established to recover gallium as a gallium chloride solution and remove arsenic ion from waste GaAs etching solution. In this study, the gallium trichloride and arsenic trisulfide powders were dissolved in ammonia solutions to prepare the simulated solutions, and the pH value was adjusted to pH 2 by nitric acid. In the extraction step, the GaAs etching solutions were extracted using 0.5 M Cyanex 272 solutions in kerosene at pH 2 and 0.1 O/A ratio for 5 min. The extraction efficiency attained 77.4%, which had an optimal ratio of concentration, and the four steps extraction efficiency attained 99.5%. After extraction, iron sulfate heptahydrates were added into the raffinate, and the arsenic ions were precipitated. The removed rate attained 99.9% when the Fe/As ratio was 10. In the stripping step, the organic phase was stripped with 0.5 M hydrochloric acid at 1 O/A ratio for 3 min, and 97.5% gallium was stripped. Finally, the purity of gallium chloride solution was 99.95% and the gallium was seven times the concentration of the etching solutions. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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10 pages, 981 KiB  
Article
Application of Fenton Method for the Removal of Organic Matter in Sewage Sludge at Room Temperature
by Yan-Jhang Chen, Tang-Yu Fan, Li-Pang Wang, Ta-Wui Cheng, Shiao-Shing Chen, Min-Hao Yuan and Shikun Cheng
Sustainability 2020, 12(4), 1518; https://doi.org/10.3390/su12041518 - 18 Feb 2020
Cited by 21 | Viewed by 3729
Abstract
Cement is the most widely used construction material in the world. However, its manufacture is high energy consumption and high carbon emission owing to the high temperature calcination process. Geopolymer is an ideal alternative material for cement because it has a similar structure [...] Read more.
Cement is the most widely used construction material in the world. However, its manufacture is high energy consumption and high carbon emission owing to the high temperature calcination process. Geopolymer is an ideal alternative material for cement because it has a similar structure and performance to cement. In addition, it can be synthesized at room temperature and thus has the advantages of energy saving and carbon emission reduction. Sewage sludge (SS) can be used as raw material for geopolymer synthesis. However, the high organic matter content in SS lowers the mechanical strength of geopolymer. Although the organic matter in SS can be removed by incineration at high temperature, this consumes energy and emits carbon dioxide, which diminishes the advantages of geopolymer. In this study, the Fenton method was applied for the removal of organic matter in SS at room temperature. The parameters of the Fenton method, including the dosages of hydrogen peroxide (H2O2) and Fe2+ reagent (FeSO4·7H2O), reaction time, and initial pH value, were investigated. The results indicated that 83.7% of the organic matter in SS could be removed at room temperature by using 5.15 M H2O2 and 5.15 mM FeSO4·7H2O at pH 7, which suggested the possibility of sewage sludge reclamation through geopolymer synthesis as an alternative material for cement toward sustainability. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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11 pages, 1199 KiB  
Article
A Study on Reduction of Copper Smelting Slag by Carbon for Recycling into Metal Values and Cement Raw Material
by Jei-Pil Wang and Urtnasan Erdenebold
Sustainability 2020, 12(4), 1421; https://doi.org/10.3390/su12041421 - 14 Feb 2020
Cited by 38 | Viewed by 5928
Abstract
Copper smelting slag is a solution of molten oxides created during the copper smelting and refining process, and about 1.5 million tons of copper slag are generated annually in Korea. The oxides in copper smelting slag include ferrous (FeO), ferric oxide (Fe2 [...] Read more.
Copper smelting slag is a solution of molten oxides created during the copper smelting and refining process, and about 1.5 million tons of copper slag are generated annually in Korea. The oxides in copper smelting slag include ferrous (FeO), ferric oxide (Fe2O3), silica (SiO2 from flux), alumina (AI2O3), calcia (CaO) and magnesia (MgO). The main oxides in copper slag, which are iron oxide and silica, exist in the form of fayalite (2FeO·SiO2). Since copper smelting slag contains high content of iron, and copper and zinc, common applications of copper smelting slag can be used in value-added products such as abrasive tools, roofing granules, road-base construction, railroad ballast, fine aggregate in concrete, etc. Some studies have attempted to recover metal values from copper slag. This research was intended to recover ferrous alloy contained Cu, a raw material of zinc, from copper slag, and produce reformed slag such as blast furnace slag for Portland cement. As a result, it was confirmed that with reduction smelting by carbon at temperatures above 1400 °C, it is possible to recover pig iron containing copper from copper smelting slag, and the addition of CaO in reduction smelting helped to reduce iron oxide in the fayalite and change the chemical and mineralogical composition of the slag. The copper oxide in the slag can be easily reduced and dissolved in the molten pig iron, and zinc oxide is also reduced to a volatile zinc, which is removed from the furnace as fumes, by carbon during the reduction process. When CaO addition is above 5%, acid slag is completely transformed into calcium silicate slag and is observed to be like blast furnace slag. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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15 pages, 3752 KiB  
Article
Sorption of Cd2+ and Pb2+ on Aragonite Synthesized from Eggshell
by Lulit Habte, Natnael Shiferaw, Mohd Danish Khan, Thenepalli Thriveni and Ji Whan Ahn
Sustainability 2020, 12(3), 1174; https://doi.org/10.3390/su12031174 - 6 Feb 2020
Cited by 18 | Viewed by 2995
Abstract
In the present work, waste eggshells were used as a precursor for the synthesis of aragonite crystals through the wet carbonation method. Cadmium (Cd2+) and lead (Pb2+) were removed by the synthesized aragonite from synthetic wastewater. The influence of [...] Read more.
In the present work, waste eggshells were used as a precursor for the synthesis of aragonite crystals through the wet carbonation method. Cadmium (Cd2+) and lead (Pb2+) were removed by the synthesized aragonite from synthetic wastewater. The influence of initial solution pH, contact time, Cd2+ and Pb2+ concentration, and sorbent dosage were evaluated. The major sorption was observed in the first 100 mins and 360 mins for Pb2+and Cd2+ respectively reaching sorption equilibrium at 720 mins (12 hr). The sorption capacity toward Pb2+ was much higher than toward Cd2+. Both heavy metals displayed high sorption capacities at initial pH 6. The pseudo-second-order kinetic model fits well with the experimental data with a higher correlation coefficient R2. Two isotherm models were also evaluated for the best fit with the experimental data obtained. Langmuir isotherm best fits the sorption of the metals on aragonite synthesized from eggshells. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) results of sorbent after sorption showed that the mechanism of sorption was dominated by surface precipitation. Therefore, aragonite crystals synthesized from waste eggshells can be a potential substitute source for the removal of Cd2+ and Pb2+ from contaminated water. Full article
(This article belongs to the Special Issue EARTH 2019-Green Technologies for Resources and Materials Recycling)
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