NaOH-modified mesoporous biochar derived from tea residue for methylene Blue and Orange II removal

https://doi.org/10.1016/j.cherd.2021.01.008Get rights and content

Highlights

  • Tea residue-based biochar modified by NaOH was prepared.

  • NaOH promoted the formation of mesoporous of the modified biochar.

  • The mesoporous of the biochar made great contribution to the adsorption.

  • The adsorption process can be described by the pseudo-second-order kinetics.

Abstract

To enhance the adsorption capacity via increasing the pore filling, the exchangeable ions content and electrostatic interaction, a late-model NaOH modified tea biochar for MB and OR-II removal was prepared. The effects of pyrolysis temperature, mass ratio of NaOH/tea residue powder (TRP) and other operation parameters, such as initial pH of the solution, contact time, initial concentration of dyes and adsorbent dosage on OR-II and MB removal in aqueous solution were studied by batch adsorption experiment. The results showed that with 10% w/w NaOH/TRP and pyrolysis at 700℃, the maximum adsorption capacities of BH700-10 of 105.27 and 91.68 mg/g for 250 mg/L MB and OR-II at pH10 or 2, respectively, were observed at 60 min. The adsorption isotherms of MB were in accordance with Langmuir and Sips models while the adsorption of OR-II was better described by the Freundlich model. The pseudo-second-order kinetic model could better describe the adsorption process. The possible interactions involved in the adsorption process was proposed. The results of this study indicated that BH700-10 is a promising low-cost adsorbent in dye wastewater treatment.

Introduction

In the progress of using water resources, human activities inevitably bring some organic synthetic dyes into the water environment, which not only reduces the utilization value of water, but also aggravates the pollution of water resources and ecological environment (Carvalho and Santos, 2016; Barbosa et al., 2016). The textile, dye, leather, cosmetics, and the paper industry produce wastewater from the coloring process that contains dyes and pigments. Methylene blue (MB) and orange II (OR-II), which have complex aromatic molecular structures, are widely used in textile printing and dyeing industry, and may cause various diseases such as kidney, brain, liver and central nervous system dysfunction (Lazar, 2005). Therefore, it is very important to exploit a high-effective method for MB and OR-II polluted effluent treatment.

Adsorption (Li et al., 2013; Liu et al., 2014), membrane method (Kazemi et al., 2013), coagulation (Morshedi et al., 2013), flocculation (Yang et al., 2013), and galvanic oxidation (Raghu et al., 2009) were usually utilized to remove dyes from wastewater. Among these techniques, adsorption is widely applied to purify the industrial effluent because of its high adsorption efficiency, low operating cost, easy recycling and alternative adsorbents. Among various adsorbents, carbon-based materials have been identified as an ideal candidate for pollutant removal and potential application due to its controllable structures and abundant functional groups (Heidari et al., 2019; Liu et al., 2015). Compared to activated carbon, biochar is less carbonized with more oxygen-containing functional groups that providing more binding sites for pollutants uptake and stable carbon retained that minimizing the emission of greenhouse gases. Moreover, the organic-loaded biochar can serve as nutrients for subsequent application as a soil amendment or recover bio-energy (Laird et al., 2009; Kong et al., 2014; Lehmann et al., 2006). Thus, from a holistic environmental pivot, the application of biowaste-derived biochar adsorbent was considered as a sustainable pathway (Lehmann et al., 2006).

In recent years, researchers have used cheap and renewable biomass precursors to produce biochar, such as corn straw (Tan et al., 2020), scallion sheathings (Song et al., 2019), tea residue (Trinh et al., 2020), reed (Wang et al., 2019a), waste rice husk (Han et al., 2020) sawdust and cow dung (Feng et al., 2013), urtica (Peydayesh et al., 2015), and platanus orientalis leaf powder (Peydayesh and Rahbar-Kelishami, 2015). As a popular beverage around the world, the tea is produced about 3,000,000 tons annually in China, and the huge consumption of tea produces tea residue on a large scale (Chen et al., 2020). As a solid waste and biomass supplement, the tea residue contains various components, such as tea polyphenols, natural pigments and proteins, which enhanced it as a great potential adsorbent material for pollutant uptake (Tang et al., 2019Wang and Wang, 2019).

Compared with pure biochar, NaOH modified biochar improved reportedly the mesoporous structure and exhibited higher adsorption capacity (Guo et al., 2012). Choudhary, etc. employed the cladodes of cactus branch to prepare the renewable adsorbent by surface modification of biochar with NaOH, which enhanced the quantity of oxygen-containing surface functional groups, thus improving the surface alkalinity of biochar, to further improve the adsorption of malachite green, Cu2+ and Ni2+ (Choudhary et al., 2020). The cacao shell waste was utilized to prepare biochar by using one-step or two-step NaOH activation for the treatment of a mixture of bright green, rhodamine B and methyl orange (Córdova et al., 2020). As far as we know, there are few researches on the removal of MB and OR-II from aqueous solution by taking tea residue as a raw material and NaOH chemical modification to produce biochar adsorbent. The preparation of biochar from waste tea residue by pyrolysis can simultaneously realize the high value utilization of solid waste and address the environmental issues.

Therefore, the main purposes of this study are: (i) to evaluate the possibility of waste tea residue conversion into biochar, (ii) to investigate the effects of NaOH introduction and pyrolysis temperature on the structure and adsorption capacity of biochar toward MB and OR-II, and (iii) to explore the possible adsorption mechanism of MB and OR-II onto BH700-10 for better understanding the adsorption process.

Section snippets

Material

Tea was selected as biomass raw material and obtained from An’Xi County (Fujian, China). The samples were pretreated by air drying and crushing, washed with deionized water, and dried in a dying oven at 90 °C for 12 h and then cooled to room temperature. The dried tea powder was then grounded and sieved through 100 meshes to obtain the tea residue powder (TRP).

The purities of NaOH, HCl, methylene blue and orange II were in A.R. grade and purchased from Sinopharm Chemical Reagent.

Synthesis of NaOH modified biochar

As a

Effects of NaOH:TRP ratio and pyrolysis temperature on MB and OR-II adsorption

According to the literature reported (Dinh et al., 2020), pyrolysis temperature plays a crucial role on the structure and properties of biochar. Generally, under oxygen restriction atmosphere and high temperature, the functional groups of tea biomass decompose gradually and release some low molecular weight gaseous compounds, such as water, methane, carbon dioxide and carbon monoxide, which could be absorbed by NaOH. At the same time, the formation of H2O and CO2 in the system play a positive

Conclusion

A novel BH700-10 biochar was successfully synthesized by pyrolysis of tea waste with the assistance of NaOH, and exhibited an abundant mesoporous structure with the average pore diameter of 3.67 nm and graphitized orderly carbon layer. BH700-10 was proved to be an efficient adsorbent to remove MB and OR-II from aqueous solution. The optimal adsorption conditions for MB and OR-II were initial pH of 10 and 2, respectively, and contact time of 60 min at a NaOH/TP mass ratio of 10% w/w and

Declaration of Competing Interest

The authors report no declarations of interest.

References (65)

  • A. Heidari et al.

    Evaluation of fast and slow pyrolysis methods for bio-oil and activated carbon production from eucalyptus wastes using a life cycle assessment approach

    J. Clean. Prod.

    (2019)
  • M.A. Islam et al.

    Methylene blue adsorption on factory-rejected tea activated carbon prepared by conjunction of hydrothermal carbonization and sodium hydroxide activation processes

    J. Taiwan. Inst. Chem. E.

    (2015)
  • S.H. Kong et al.

    Biochar from oil palm biomass: a review of its potential and challenges

    Renew. Sust. Energ. Rev.

    (2014)
  • S. Larous et al.

    Adsorption of diclofenac from aqueous solution using activated carbon prepared from olive stones

    Int. J. Hydrogen. Energ.

    (2016)
  • Y. Li et al.

    Methylene blue adsorption on graphene oxide/calcium alginate composites

    Carbohydr. Polym.

    (2013)
  • Y. Liu et al.

    Attapulgite/bentonite interactions for methylene blue adsorption characteristics from aqueous solution

    Chem. Eng. J.

    (2014)
  • D. Morshedi et al.

    Using protein nanofibrils to remove azo dyes from aqueous solution by the coagulation process

    Colloids Surf. B Biointerfaces

    (2013)
  • N. Nasuha et al.

    Adsorption of methylene blue from aqueous solution onto NaOH-modified rejected tea

    Chem. Eng. J.

    (2011)
  • N. Nasuha et al.

    Rejected tea as a potential low-cost adsorbent for the removal of methylene blue

    J. Hazard. Mater.

    (2010)
  • A.E. Ofomaja et al.

    Equilibrium sorption of anionic dye from aqueous solution by palm kernel fibre as sorbent

    Dye. Pigment.

    (2007)
  • S. Pandey et al.

    Organic-inorganic hybrid of chitosan/organoclay bionano composites for hexavalent chromium uptake

    J. Colloid Interface Sci.

    (2011)
  • M. Peydayesh et al.

    Adsorption of methylene blue onto Platanus orientalis leaf powder: kinetic, equilibrium and thermodynamic studies

    J. Ind. Eng. Chem.

    (2015)
  • S. Raghu et al.

    Evaluation of electrochemical oxidation techniques for degradation of dye effluents—a comparative approach

    J. Hazard. Mater.

    (2009)
  • X. Song et al.

    2D magnetic scallion sheathing-based biochar composites design and application for effective removal of arsenite in aqueous solutions

    Chem. Eng. Res. Des.

    (2019)
  • G. Tan et al.

    A comparative study of arsenic(V), tetracycline and nitrate ions adsorption onto magnetic biochars and activated carbon

    Chem. Eng. Res. Des.

    (2020)
  • M.T. Uddin et al.

    Adsorptive removal of methylene blue by tea waste

    J. Hazard. Mater.

    (2009)
  • I. Ullah et al.

    Biosorption of chromium onto native and immobilized sugarcane bagasse waste biomass

    Ecol. Eng.

    (2013)
  • J. Wang et al.

    Preparation, modification and environmental application of biochar: a review

    J. Clean. Prod.

    (2019)
  • J. Wang et al.

    Catalytic effects of six inorganic compounds on pyrolysis of three kinds of biomass

    Thermochim. Acta

    (2006)
  • K. Wang et al.

    Synthesis of silica-composited biochars from alkali-fused fly ash and agricultural wastes for enhanced adsorption of methylene blue

    Sci. Total Environ.

    (2020)
  • C. Wang et al.

    Waste printed circuit boards as novel potential engineered catalyst for catalytic degradation of orange II

    J. Clean. Prod.

    (2019)
  • Z. Yang et al.

    Flocculation of both anionic and cationic dyes in aqueous solutions by the amphoteric grafting flocculant carboxymethyl chitosan-graft-polyacrylamide

    J. Hazard. Mater.

    (2013)
  • Cited by (72)

    View all citing articles on Scopus
    View full text