Elsevier

Chemosphere

Volume 287, Part 3, January 2022, 132250
Chemosphere

Biochar derived from fruit by-products using pyrolysis process for the elimination of Pb(II) ion: An updated review

https://doi.org/10.1016/j.chemosphere.2021.132250Get rights and content

Highlights

  • Various type of fruit waste as a potential adsorbent to remove Pb(II) is reviewed in this study.

  • Overview of preparation of biochar derived from fruit waste using pyrolysis process is described.

  • A detail of possible adsorption mechanisms of Pb(II) ion onto biochar are elaborated.

  • Prospective of biochar regeneration cycles performance is summarised.

Abstract

Water pollution is one of the most concerning global environmental problems in this century with the severity and complexity of the issue increases every day. One of the major contributors to water pollution is the discharge of harmful heavy metal wastes into the rivers and water bodies. Without proper treatment, the release of these harmful inorganic waste would endanger the environment by contaminating the food chains of living organisms, hence, leading to potential health risks to humans. The adsorption method has become one of the cost-effective alternative treatments to eliminate heavy metal ions. Since the type of adsorbent material is the most vital factor that determines the effectiveness of the adsorption, continuous efforts have been made in search of cheap adsorbents derived from a variety of waste materials. Fruit waste can be transformed into valuable products, such as biochar, as they are composed of many functional groups, including carboxylic groups and lignin, which is effective in metal binding. The main objective of this study was to review the potential of various types of fruit wastes as an alternative adsorbent for Pb(II) removal. Following a brief overview of the properties and effects of Pb(II), this study discussed the equilibrium isotherms and adsorption kinetic by various adsorption models. The possible adsorption mechanisms and regeneration study for Pb(II) removal were also elaborated in detail to provide a clear understanding of biochar produced using the pyrolysis technique. The future prospects of fruit waste as an adsorbent for the removal of Pb(II) was also highlighted.

Introduction

The global human population is set to overshoot to 9.9 billion people by 2050 from the current living 7.8 billion people (PRB, 2020). The growing human population and increased development would not only boost the demand for food but also lead to serious food wastages (Baig et al., 2019). The United Nations Food and Agriculture Organization (FAO) reported that a billion tonnes of food are wasted every year of which 60% is contributed from solid food waste, including fruit and vegetable by-products comprising peeled skin, seeds, and stones, which ultimately pose a serious waste disposal problem (FAO, 2020b; Sagar et al., 2018). For instance, in Malaysia, approximately 20–50% of fruits and vegetables are usually discarded, indicating that almost half of the agricultural yields are lost during the process of food management (Sulaiman and Ahmad, 2018). These food residues are usually placed in a bin, thrown down the drain, or fed to animals. In fact, the significant contribution of fruit and vegetable wastes in municipal solid waste has become the biggest challenge to local authorities and city councils in developing countries to handle the issue of solid waste management.

Furthermore, the rising volume of food waste has afflicted increasing burden on environmental issues. Inappropriate management of landfill waste would result in the release of methane and carbon dioxide as well as the increasing cost of the municipal budget for waste management (Deng et al., 2012; Lipiński et al., 2018; Lopez Barrera and Hertel, 2021). In addition, the huge amount of waste generated from fruit and vegetable could severely impact the climate, water bodies, land, and overall biodiversity. Although many efforts have been implemented by various governments and international bodies through the setting up of waste management policies and aggressive awareness campaigns to educate the community, the outcome is still far from expected as the problem is complicated, especially in the context of agriculture waste management (Jayashree et al., 2012).

In order to promote a zero-waste strategy, the conversion of fruit waste into value-added products is one of the alternative solutions to minimise the waste generation issue (Sirohi and Pandey, 2019). Based on the findings from past researches, it was concluded that certain fruit wastes possess great potential to be transformed into other useful products, such as biochar that can be utilised as an adsorbent to adsorb metal ions from water or wastewater. Fruit waste has been proven to be a good adsorbent due to the high content of functional groups, such as carboxylic acid and hydroxyl groups, on the surface of the fruit peel. These functional groups aid in the elimination of heavy metal ions using ion-exchange or complexation, thus, increasing the adsorption capacity (Chao et al., 2014; Saini et al., 2020). The advantages of fruit waste as low-cost adsorbents have been reported in previous studies, including cost-effective and environmentally friendly material, widely available, requires minimal treatment, and is highly efficient (Chao et al., 2014; Kumar et al., 2019). Since the properties of adsorbents serve as a crucial factor for the adsorption of metal ions; hence, research on the development of low-cost and effective adsorbents for heavy metal removal is of great significance. To date, the global scientific community have put in a lot of effort in search of effective alternative adsorbents from cheap raw materials. The persistent effort can be measured by analysing the database in ScienceDirect by entering the keywords “fruit waste as an adsorbent for heavy metal ion removal”. The search retrieved 16 research articles published in 2000 and approximately 409 research articles as of July 2021. The increasing trend of published articles indicates the deep interest among many researchers on this topic. The introduction of fruit waste-based adsorbent is beneficial to the economy and is capable to provide competitive performance with commercial activated carbon. It can also be used in many applications, including gas adsorption and recovery of metals present in the wastewater (Deng et al., 2012).

According to the Agency for Toxic Substances and Disease Registry, lead (Pb) ranked second (after arsenic) as the most toxic element among the hazardous metals (ATSDR, 2020). It has been considered one of the most toxic heavy metals in the ecosystem. Therefore, cost-effective methods and high adsorption capacity performance are needed for Pb(II) ion removal. This review provides a solid foundation on the utilisation of fruit wastes for heavy metals removal and adds significant insights into the importance of creating sustainable solutions that can minimise waste generation. To the best of our knowledge, a systematic and comprehensive review on the conversion of fruit waste as biochar using the pyrolysis method, a detailed description of the preparation of biochar, and the relationship between adsorption mechanisms and adsorption capacity of biochar emphasising on Pb(II) removal has not yet been reported to this day. Hence, this review attempts to address the aforementioned research gap by setting up the review paper as follows: the introductory section provides an overview of the overwhelming fruit waste issue and the solution to tackle the problem. The second section describes a full detail of the review methodology that was carried out in the study to collect data from the selected database. Next, a detailed explanation of Pb(II) properties based on their chemical, physical, and mechanical properties is given, followed by a discussion on the effect of Pb(II) on humans. A more in-depth discussion on the variety of low-cost materials derived from fruit waste residue is presented, which focused on the preparation step of biochar using pyrolysis and other conversion method as well as the possible mechanism during the reaction process. Finally, this paper concludes with an overview of the main findings and several suggestions for future studies on the potential treatment technologies using fruit waste-based adsorbents.

The specific objectives of this review are as follows:

  • To summarise the scientific inventions and reviews on various types of fruit waste as an effective adsorbent for the adsorption of Pb(II) ions from synthetic and real wastewater.

  • To provide detailed information on the preparation step of biochar using pyrolysis and other conversion method as well as the possible mechanisms associated with these materials.

This paper would provide greater understanding to new researchers regarding the preparation of biochar from fruit waste through the pyrolysis technique as well as offering fresh and innovative ideas from the current research that can be applied in their research work. This information is very useful for researchers that aim to venture into this field. For experienced researchers, this paper would fulfil the role as a central referral point to dissect recent progress on fruit waste-based adsorbents and the adsorption mechanism in proposing future research directions. Overall, this review paper would be considered a significant point of reference for future studies.

In 1999, Moher et al. (1999) developed a standard checklist item for the preparation of a meta-analyses report on the randomised clinical controlled trials using the Quality of Reporting of Meta-analyses (QUOROM) statement. Moher et al. (2009) also published an article to introduce a standardised methodology and a flow diagram to report systematic reviews, which is known as the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The PRISMA systematic review was used primarily to provide supporting reports on medical studies for well-informed decision-making in the health sector. Since then, the application of systematic review methodology has spread beyond the medical fields, including in software engineering, education, social welfare and international development, and the public and environmental health sector. PRISMA is now widely used by a range of journals as a pre-submission checklist, specifically for review articles. Given that PRISMA was developed for systematic reviews in the healthcare sector, it has limited applicability for reviews in other scientific fields, such as engineering and environmental management.

The PRISMA is a standard guideline for conducting systematic reviews to guide researchers to improve the reporting of systematic reviews and produce high-quality literature review with complete information (Ahn and Kang, 2018). The methodology also provides an item checklist for researchers to examine their reports, such as the value of their systematic review to users and improving the objective and outcomes of the report, completely and accurately. The standard flow diagrams for the original and updated reviews as well as the checklist are available on the PRISMA statement website (PRISMA, 2021). In the present review study, the PRISMA method was employed based on the standard guidelines, including literature search for a specific topic, choosing the suitable published papers, extraction of data, and summarising (see Fig. S1 in the Supplementary file). Thus far, there is no systematic review article has been published on the potential of fruit waste as an adsorbent to eliminate Pb(II) ions using the PRISMA method.

The keyword-based search for this review as demonstrated in the Supplementary file (Table S1) was conducted based on the PRISMA guidelines. Currently, there is limited information on the potential use of fruit waste as an effective adsorbent to eliminate Pb(II) ions. Most of the top-tier databases (such as Web of Science or Scopus), only listed few studies related to this field, while many of the research focused on other types of raw material (waste material) or adsorbents. The total of publications related to this topic based on the Web of Science database is 340 articles and 447 articles from the Scopus database. The number of publications was highest in 2020 and the lowest was in 2008 and 2009. The highest number of published articles were from India followed by China and Brazil.

In this review, all the scientific information was compiled from the database following the PRISMA method. Firstly, a literature search was carried out using the combined search results from multiple databases, including Scopus, Web of Science and ScienceDirect. The language used for the title, abstract, and full article was selected based on the articles published in the English language only. In order to include as many literature reports as possible, the keywords were emphasised on fruit waste materials that are commonly found in developing countries. In addition, a suitable keyword to search for research and review articles was based on the relevant literature and summarised publications on the elimination of Pb(II) via adsorption. The search strategy was based on the selected keywords and a combination of the keywords such as “fruit waste AND adsorption AND Pb(II)” OR “fruit waste AND adsorption AND lead” OR “fruit waste AND adsorption AND heavy metal” OR “fruit waste AND pyrolysis AND Pb(II)” OR “fruit waste AND pyrolysis AND lead” OR “fruit waste AND pyrolysis AND heavy metal”. These keywords were chosen to search for better input and suitable information regarding the preparation step of biochar, possible mechanisms associated with these materials, and regeneration studies on the adsorption of Pb(II) using fruit waste as adsorbents.

The second step of the PRISMA method involved the classifying of the published articles and filtering of unrelated data using Microsoft Excel 2019 (Microsoft, USA). The collected data were screened by analysing the title, abstract, and full articles. Any unrelated articles from the scope of the study were removed and the data published from 2000 to 2021 was compiled.

In the final reviewing stage, the content of each published article was evaluated and valuable information from the articles was extracted.

Section snippets

Overview of Pb

Pb is one of the metal elements that have been extensively used in various applications since ancient times (Holland et al., 2003; Nriagu, 1983). They were used by the Egyptians and the Romans for glazing pottery, constructing water pipes and plumbing, and a component in cosmetics (Ghazi and Millette, 1964). Pb is also known as one of the seven metals of antiquity due to its unique properties, such as soft texture, very malleable, ductile, low melting point, a poor conductor of electricity or

Carbon-based adsorbents derived from fruit waste

The advanced development of low-cost materials as effective adsorbents from agricultural wastes to treat wastewater has attracted the interest of researchers in the field of heavy metal, particularly the use of adsorption techniques. This is due to the easily available, cheap, eco-friendly material, and low processing requirement to setup the adsorption process (Abegunde et al., 2020; Malik et al., 2017).

Fruit waste makes a suitable candidate as an adsorbent as it contains lignin,

Summary and prospects of fruit waste adsorbents

This review has presented an overview of the past and current development of Pb(II) removal using low-cost biochar from published articles between 2000 and the present, focusing on the conversion of fruit waste materials into biochar for the adsorption of Pb(II). This study provided an up to date scientific inventions and reviews on the various type of fruit by-products for effective adsorption of Pb(II) ions from water and wastewater. This study also presented detailed information on the

Credit author contribution statement

Farihahusnah Hussin: Writing - original draft, collecting and analysis journal articles. Mohamed Kheireddine Aroua: Reviewing & Editing, Supervision. Małgorzata Szlachta: Reviewing & Editing final version of manuscript and provide resources to address reviewer comments.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The author would like to thank Sunway University and Research Service for the research funding provided (grant no. GRTIN-IRG-33-2021).

References (248)

  • D. Alsafadi et al.

    Utilizing the crop waste of date palm fruit to biosynthesize polyhydroxyalkanoate bioplastics with favorable properties

    Sci. Total Environ.

    (2020)
  • J. Anwar et al.

    Removal of Pb(II) and Cd(II) from water by adsorption on peels of banana

    Bioresour. Technol.

    (2010)
  • Y. Artioli

    Adsorption

  • S.S. Bagali et al.

    Optimization, kinetics, and equilibrium studies on the removal of lead (II) from an aqueous solution using banana pseudostem as an adsorbent

    Engineering

    (2017)
  • A. Bagreev et al.

    Thermal regeneration of a spent activated carbon previously used as hydrogen sulfide adsorbent

    Carbon

    (2001)
  • M.B. Baig et al.

    Food waste posing a serious threat to sustainability in the Kingdom of Saudi Arabia – a systematic review

    Saudi J. Biol. Sci.

    (2019)
  • A. Balaria et al.

    Assessment of biosorption mechanism for Pb binding by citrus pectin

    Separ. Purif. Technol.

    (2008)
  • M. Balat et al.

    Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 1: pyrolysis systems

    Energy Convers. Manag.

    (2009)
  • S. Baloch et al.

    Occupational exposure of lead and cadmium on adolescent and adult workers of battery recycling and welding workshops: adverse impact on health

    Sci. Total Environ.

    (2020)
  • M.A. Barakat

    New trends in removing heavy metals from industrial wastewater

    Arab. J. Chem.

    (2011)
  • D. Becker

    44 - evolution of pigments and dyes

  • J.K. Bediako et al.

    Characterization of the residual biochemical components of sequentially extracted banana peel biomasses and their environmental remediation applications

    Waste Manag.

    (2019)
  • S. Bhattacharjee et al.

    Removal of lead from contaminated water bodies using sea nodule as an adsorbent

    Water Res.

    (2003)
  • M. Boskabady et al.

    The effect of environmental lead exposure on human health and the contribution of inflammatory mechanisms, a review

    Environ. Int.

    (2018)
  • A.E. Burakov et al.

    Adsorption of heavy metals on conventional and nanostructured materials for wastewater treatment purposes: a review

    Ecotoxicol. Environ. Saf.

    (2018)
  • H.-P. Chao et al.

    Biosorption of heavy metals on citrus maxima peel, passion fruit shell, and sugarcane bagasse in a fixed-bed column

    J. Ind. Eng. Chem.

    (2014)
  • H. Chen et al.

    Adsorption characteristics of Pb(II) from aqueous solution onto a natural biosorbent, fallen cinnamomum camphora leaves

    Desalination

    (2010)
  • S.B. Choi et al.

    Biosorption of cadmium by various types of dried sludge: an equilibrium study and investigation of mechanisms

    J. Hazard Mater.

    (2006)
  • G.F. Coelho et al.

    Removal of metal ions Cd (II), Pb (II), and Cr (III) from water by the cashew nut shell anacardium occidentale L

    Ecol. Eng.

    (2014)
  • F.-X. Collard et al.

    A review on pyrolysis of biomass constituents: mechanisms and composition of the products obtained from the conversion of cellulose, hemicelluloses and lignin

    Renew. Sustain. Energy Rev.

    (2014)
  • R. Cossu et al.

    Chapter 10.4 - physical–chemical leachate treatment

  • S.K. Das et al.

    Applications of biomass derived biochar in modern science and technology

    Environ. Technol. Innov.

    (2021)
  • T.A. Davis et al.

    A review of the biochemistry of heavy metal biosorption by brown algae

    Water Res.

    (2003)
  • T. Depci et al.

    Competitive adsorption of lead and zinc from aqueous solution on activated carbon prepared from Van apple pulp: study in single- and multi-solute systems

    Chem. Eng. J.

    (2012)
  • E.S.Z. El-Ashtoukhy et al.

    Removal of lead (II) and copper (II) from aqueous solution using pomegranate peel as a new adsorbent

    Desalination

    (2008)
  • I. Esparza et al.

    Fruit and vegetable waste management: conventional and emerging approaches

    J. Environ. Manag.

    (2020)
  • N.-C. Feng et al.

    Characterization of adsorptive capacity and mechanisms on adsorption of copper, lead and zinc by modified orange peel

    Trans. Nonferrous Metals Soc. China

    (2012)
  • J. Feng et al.

    An environmental-friendly magnetic bio-adsorbent for high-efficiency Pb(Ⅱ) removal: preparation, characterization and its adsorption performance

    Ecotoxicol. Environ. Saf.

    (2020)
  • S.J.S. Flora et al.

    Environmental occurrence, health effects and management of lead poisoning

  • K.Y. Foo et al.

    Microwave-assisted regeneration of activated carbon

    Bioresour. Technol.

    (2012)
  • S.Y. Foong et al.

    Valorization of biomass waste to engineered activated biochar by microwave pyrolysis: progress, challenges, and future directions

    Chem. Eng. J.

    (2020)
  • F. Fu et al.

    Removal of heavy metal ions from wastewaters: a review

    J. Environ. Manag.

    (2011)
  • Z.N. Garba et al.

    Optimization of adsorption conditions using central composite design for the removal of copper (II) and lead (II) by defatted papaya seed

    Karbala Int. J. Modern Sci.

    (2016)
  • A.M. Ghazi et al.

    4 - lead

  • B.S. Girgis et al.

    Porosity development in activated carbons obtained from date pits under chemical activation with phosphoric acid

    Microporous Mesoporous Mater.

    (2002)
  • G.T. Grant et al.

    Biological interactions between polysaccharides and divalent cations: the egg-box model

    FEBS (Fed. Eur. Biochem. Soc.) Lett.

    (1973)
  • Y. Guo et al.

    Monitoring of lead, cadmium, chromium and nickel in placenta from an e-waste recycling town in China

    Sci. Total Environ.

    (2010)
  • H. Guo et al.

    Removal of cadmium(II) from aqueous solutions by chemically modified maize straw

    Carbohydr. Polym.

    (2015)
  • N. Gupta et al.

    Fruit waste management by pigment production and utilization of residual as bioadsorbent

    J. Environ. Manag.

    (2019)
  • M. Hao et al.

    Recent advances on preparation and environmental applications of MOF-derived carbons in catalysis

    Sci. Total Environ.

    (2021)
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