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Decolorization of dyes from textile wastewater using biochar: a review



The textile industry is one of the largest in many low and middle-income countries, especially in Asia, second only to agriculture. Textile wastewater is discharged into the environment due to the lack of affordable and sustainable solutions to adsorb or remove the dye from the water. Biochar is generated by pyrolysis of organic material from plant waste in low-oxygen conditions, and is considered carbon-negative. Biochar for dye adsorption in textile wastewater effluent was proven to be highly effective. However, adsorption efficiency varies with experimental parameters, therefore there is a gap in application especially in small dye houses. Efforts should be made to find innovative and affordable solution to make the textile industry more sustainable, by developing methods for collection and reuse, recycle and upcycle of textile waste, by reducing the consumption of water, energy and chemicals and by developing methods for treatment of the textile wastewater.
Acta Innovations 2020 no. 37: 36-46 36 ISSN 2300-5599 2020 RIC Pro-Akademia CC BY
Hadas Mamane*
School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University
Tel Aviv 69978, Israel,
Shir Altshuler
School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University
Tel Aviv 69978, Israel
Elizaveta Sterenzon
School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University
Tel Aviv 69978, Israel
Vinod Kumar Vadivel
School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University
Tel Aviv 69978, Israel
The textile industry is one of the largest in many low and middle-income countries, especially in Asia, second
only to agriculture. Textile wastewater is discharged into the environment due to the lack of affordable and
sustainable solutions to adsorb or remove the dye from the water. Biochar is generated by pyrolysis of organic
material from plant waste in low-oxygen conditions, and is considered carbon-negative. Biochar for dye
adsorption in textile wastewater effluent was proven to be highly effective. However, adsorption efficiency varies
with experimental parameters, therefore there is a gap in application especially in small dye houses. Efforts
should be made to find innovative and affordable solution to make the textile industry more sustainable, by
developing methods for collection and reuse, recycle and upcycle of textile waste, by reducing the consumption
of water, energy and chemicals and by developing methods for treatment of the textile wastewater.
textile dye effluent; biochar; wastewater; sustainability; contamination; sorption
Climate change, population growth, rising standards of living and uneven distribution of water are the main
causes for competition over water resources, water scarcity, poor water quality and variability of hydrological
events. Water is the core of sustainable development and unfortunately, water is not equally available and in
many areas around the world clean water is out of reach [1]. The environmental stress on water bodies is evident
in terms of not only quantity, but also quality. Globalization of industrialization has resulted in high pollution
of water resources worldwide. The major industries responsible for pollution are the dyeing industries, paper
industries, tanneries, metal-plating industry, mining operations, fertilizer industries, agricultural waste and
pesticides. The demand for water in the industrial sector is expected to increase by 283% during the first half
of the 21st century [2], resulting in increasing industrial wastewater discharge.
The textile industry is one of the largest in many low and middle-income countries, especially in Asia [3]. The
textile industry is one of the cornerstones in economies of many countries [4]. For example, the Indian textile
industry according to the India Brand Equity Foundation (IBEF), it is the second largest industry, after agriculture,
providing employment to over 45 million people directly and 60 million people indirectly, and it contributes 14%
of the Indian total industrial production [5]. Humans are aesthetically interested in dyed textile, therefore the
use of dyes in textile will not be abandoned. Different types of dyes are used in a variety of industries including
the food industry, textile, tanneries, plastics and pharmaceuticals. Many products in those industries contain
Acta Innovations 2020 no. 37: 36-46 37 ISSN 2300-5599 2020 RIC Pro-Akademia CC BY
several dyes from different chemical classes resulting in a complex wastewater [6]. Industrial dyes, in particular
used in the textile industry, have complex molecular structures, synthetic in origin and recalcitrant [7].
Most of the chemicals are added in the dyeing process where a color is added to the dye baths, the fabric
is immersed in the dye baths until the dye is fixed. In some cases, there is a need to add salt to the bath in addition
5 tons
of synthetic dye are produced annually, with 10 15% of it not ending up in the final product [4] thus eventually
further contaminating the environment.
Therefore the effluent also contains a large amount of recalcitrant unfixed dyes (as acid dyes, basic dyes, sulfur
dyes, chrome dyes, optical/fluorescent brightener and azoic dyes) as the dyes are not totally fixed to the fiber
of different textiles during the dyeing process (fibers as wool and nylon, cotton and viscose, polyester and
acrylic). The textile industry requires a large amount of water for the production process, and is also one of the
major producers of wastewater that can have carcinogenic and mutagenic compounds [9]. Wastewater from the
textile industry is frequently discharged directly into lakes and rivers without any proper treatment and often
these water sources are used by locals domestically [10,11]. Since the dyeing process uses a significant amount
of water, recycling used in the dyeing process can conserve water, however it requires treatment whether
recycled or discharged to the environment. Reference values for water reuse in textile industry, included COD
between 60- In addition to dyes,
lubricating oils and fibers [11].
Dyes cannot be removed through conventional treatment unit operations due to the complex characteristics of
the wastewater as high solubility, non-degradable nature, diversity and often changing speciation in water. When
industrial wastewater is discharged into natural water bodies it can result in hazardous effects on the living
systems because of the carcinogenic, mutagenic, allergenic and toxic nature of dyes [6]. This is a paradox as
current conventional and advanced methods for the removal or degradation of persistent and emerging textile
contaminants are limited, since they often involve intensive capital, lack of adaptive technological tools, social
barriers and emphasis on centralized systems. Consequently, to close the gap, there is a dire need for innovative
solutions and for widespread decentralized systems in the textile industry suitable for rural areas and capital-
challenged countries.
There are many treatment methods when dealing with textile wastewater. The different techniques can be based
on physical (sedimentation, filtration, floatation, coagulation, reverse osmosis, solvent extraction, adsorption,
incineration, and distillation), chemical (neutralization, reduction, oxidation, catalysis, ion exchange, electrolysis)
and biological (stabilization, aerated lagoons, trickling filters, activated sludge, anaerobic digestion) [12]. Physical
methods are very common methods in textile wastewater treatment due to their high color removal efficiency,
especially adsorption, filtration and membrane filtration. Other treatment processes as reverse osmosis,
nanofiltration and multiple effect evaporators are effective but expensive, while the common treatment
methods are non-destructive, lower in cost, time-consuming and less efficient [13].
Adsorption by porous materials is one of the most promising and affordable techniques for the removal
of dissolved pollutants, serving as an alternative to energy-intensive technologies [14]. Activated carbon is
a widely used adsorbent, but biochar, which is inexpensive, abundant and may have comparable adsorption
capacity, can be used as an affordable alternative [15-17]. However, the efficiency, local manufacturing,
availability and costs must be examined. Biochar is the result of low-temperature pyrolysis of carbon-rich
biomass (from agricultural and forestry wastes) under low-oxygen conditions [18]. As can be seen in Fig. 1, there
is an increase in the number of publications using the keywords: dye sorption, textile wastewater and biochar
(by google scholar).
Acta Innovations 2020 no. 37: 36-46 38 ISSN 2300-5599 2020 RIC Pro-Akademia CC BY
Fig. 1. Yearly number of publications using the keywords: dye sorption, textile wastewater and biochar
(by google scholar)
The biochar created is a stable carbon black solid that is highly porous with large surface area (Fig. 2.). More than
70 percent of its composition is carbon [19]. The chemical composition varies with feedstocks used
to make it and methods used to heat the biomass. The pyrolysis process varies as it can be done with different
conditions as burning temperature and burning time, reactor volume, other gasses and materials in the reactor
[20]. However, different thermochemical processes can be also used for biochar production [18]. Compared
to activated carbon, biochar can be created from various types of biomass, requires less energy in the production
process and consequently can provide a solution in the treatment of textile wastewater in poor income countries.
Fig. 2. Biochar particles image (left) and scanning electron microscopy (right, taken at Tel-Aviv University)
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The porosity and high surface area of biochar make it an excellent adsorbent of organic contaminants and heavy
metals in wastewater [17]. This has led to a growing interest in using biochar for water treatment, although most
research today focuses on its abilities for soil fertilization [15]. Adsorption of textile dyes was examined with
various biochar types [15,21,22]. For each type of dye, the biochar type, process parameters (temperature, pH,
agitation time) and wastewater quality influence the efficiency of the dye removal from the wastewater. Most
studies have focused on the removal of pure, highly concentrated dye solutions that do not represent the actual
effluent from real dye houses. Real effluent may contain lower dye concentrations and additional substances
as previously mentioned, such as salts, detergents, solids, and fiber residuals, which have a tremendous effect
There are numerous types of dyes and biochars and therefore the biochar type and dose should match the dye
type. The major anionic dyes are the acid and reactive dyes, and the most problematic ones are the brightly
colored, water-soluble acid dyes [23]. Acid dyes are a sub-group of anionic dyes and are called so, because they
are usually applied to the fibers in acid solutions [24]. Cationic dyes are dyes that can be dissociated into
positively charged ions in the aqueous solution, and the cationic dye dyes the fiber through the binding of its
cation ion [7,23]. Basic dye, are highly visible and have high brilliance and intensity of colors [25].
As mentioned above, the textile industry uses different colors, each with its own properties and characteristics.
Moreover, the biochar itself can vary based on the initial biomass from which it is produced. In order to find the
best biochar-dye combination, a summary of articles examining different combinations was made [26-43].
In these articles, the biochar efficiency in removing the dye from a mixture was calculated using mass balance
equation for dye adsorption on biochar [37].
Table 1 summarizes different characteristics from 1 articles that present the use of biochar in treatment
of textile wastewater [26-43]. The articles are catagorized to biochar properties, dye properties, experimental
conditions, dye adsorption experiments compared to a common biochar and modified biochar. All the
experiments presented were batch experiment in a controlled environment. From the table it is evident that
there are some differences between the treatment requirements for cationic dyes and anionic dyes. The
adsorption of the dye to the biochar depend on the characteristics of the solution, the type of the biochar and
the conditions in which the experiment was performed.
One of the critical conditions is the solutions pH, where the adsorption of cationic dyes will be maximized when
the pH of the solution is basic and anionic dyes in acidic pH, with preferred pH at . The pH of the solution has
a significant effect on the interaction of the dyes with the biochar in the adsorption process. For example, the
effects of the solutions pH were examined on the adsorption of three dyes, Methyl Orange, an anionic dye and
Malachite green & Methylene blue, both cationic dyes and three types of biochar, each produced with a different
solvent (acetone, ethanol and methanol) [30]. The adsorption of the cationic dye Malachite Green onto the
biochar increased with the increase in pH. The solution pH influenced the adsorption through dissociation
of functional groups on the active sites of the biochar. In another study, the adsorption of anionic dye Reactive
Red 141 onto a Pecan Nutshell based biochar occured mostly in an acidic environment with a low pH [32]. Under
acidic conditions, the biochar surface is positively charged whereas the Reactive Red 141 has several sulfonated
groups, which are negatively charged that are attracted to the biochar surface, increasing the dye removal
The dye to biochar interaction depends on the temperature of the mixture, the interaction time, the steering
speed and more. Almost all the experiments showed that a temperature of 25-30oC is the optimal temperature
ocity in the mixture and
will reduce the adsorption [27]. This result is significant because it means the treatment will not require any
major heating or cooling systems and the treatment can be effective in real wastewater. The interaction time is
also a crucial parameter. With short interaction time, the dye will not be able to sufficiently interact with the
biochar, while with long interaction time, the binding between the dye and the biochar could become loose, and
the biochar can undergo modifications that can damage its functionality and even release material and pollutants
to the water and cause more damage [27,30,34]. Each biochar-dye combination has its own optimal interaction
on the other conditions regulating
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the environment. Mubarak et. al. showed an increase in removal effecincy with contact time of methylene blue
(cationic) and orange-G (anionic) onto Empty fruit bunch based biochar [36]. Another factor that can affect the
interaction is the rotation speed of the mixture. A high rotation speed can lead to a high shear stress that can
break the bindings between the biochar and the dye and can even damage the biochar particles and thus lower
its efficiency. The most common rotation speed as presented in Table 1, is ~130-150 rpm.
Several studies attempted to increase an existing biochar activity by performing different modifications on it as
Iron impregnation biochar, addition of cationic surfactant to the biochar surface, inserting magnetic formation
to the biochar and more. These new characteristics provide the biochar with a stronger affinity and interaction
between the biochar and the dye. One example of the benefits of these modifications used Rice Husk derived
biochar mixed with a solution containing an aqueous phase reduction of ferrous iron (FeSO47H2O) called nZVI,
resulting in attachment of nanoscale zero-valent iron particles to the biochar creating a modified biochar
(nZVI/BC) to adsorb the anionic dye Methyl Orange. In this experiment, three types of biochar various theoretical
mass ratios of nZVI/BC at 1:3, 1:5, and 1:7 [28]. The nZVI/BC 1:5 adsorbed almost 100% of the dye in the mixture
compared to the other modified biochars that peaked at 90% and the non-modified biochar that reached only
10%. Although there may be an advantage in using modified biochar, there might be a problem after extended
usage. For example, high concentrations of oxygen can convert the Fe0 molecules into ferrous or ferric oxide
leading to a passivation layer forming on the nZVI surface.
Table 1. A summary of articles presenting biochar source, postproduction modifications, dye type, optimal conditions and
experimental results
Optimal Condition Results Refere
pH Temp
RPM Contact
Pyrolysis at
450oC for 4
200 cm3
STP/min of
N2 was fed into the
reactor, and steam
was used as the
activation agent at
2 h.
Modification goals:
Enhancement of
textural properties.
Congo Red
Violet (CV)
30 150 CR:750
Color and COD
efficiencies up
to 99.6% and
67.7% for CV.
Color and COD
efficiencies up
to 10.3% and
23.7% for CR.
Rice husk
(RHB) and
Coir pith
Pyrolysis at
700oC for 5
RHB or CPB were
added to a solution
containing Fe
(NO3)3 2O
dissolved in water.
The mixture was
oven dried at 105
followed by
calcination at 500
Modification goals:
Provide the biochar
with oxidizing
Acid Red 1
3 30-50
150 120
removal for Fe-
RHB was 97.6%.
removal for Fe-
CPB was 99.1%
Rice husk Pyrolysis at
Biochar was mixed
with HCl for
then mixed with
different mass
ratios of nZVI.
4 - 15 Maximum dye
removal for
nZVI at 5:1 was
capacity of
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Modification goals:
increase dye
adsorption by
transforming it to
low molecular
weight products
destruction of its
N=N bonds.
306.7, 605.0,
and 709.1
mg/g for initial
and 600 mg/L,
Bael shell
Pyrolysis at
500oC for 3
The biochar did n
undergo any
blue (PB)
2.7 - 110 60 Maximum dye
removal was
74% (3.7 mg/g)
(CM) from
raw chicken
Pyrolysis at
600oC for 2
The biochar did not
undergo any
6.5 25 150 30 Almost 100% dye
sludge (SS)
acetone as
the solvent
at 260-280
The biochar did not
undergo any
blue (MB)
Acetone based
solution gave
The bio-chars
were only
effective on
cationic MG
and MB with
removal of 10
40 mg/g and
15 45 mg/g
Pyrolysis at
400oC for 5
The biochar did not
undergo any
blue (MB)
8 25 125 30 Maximum
44.13 mg/g
Pyrolysis at
800oC for 1
The biochar did not
undergo any
Red 141
2-3 25 250 80
within 10 min
Palm Kernel
Shell (PKS)
Pyrolysis at
350oC in a
rotary kiln
for 20 min
The biochar did not
undergo any
Violet (CV)
6 25 100 30 maximum
24.45 mg/g
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by cationic
Pyrolysis at
C for 20
Biochar added to a
solution of
bromide (TTAB) in
Modification goals:
binding a cationic
Red (RR-
5 25 150 40 Dye removal
from different
Tap water %:
10 - 96.61
surfactant to the
biochar to form
micelle like
structures which
can solubilize dye
within this
structure and
increase the
30 - 98.82
50 - 98.76
Raw water %:
10 - 98.56
30 - 97.79
50 - 99.26
Wastewater %:
10 - 100.00
30 - 94.83
50 - 94.24
Sea water %:
10 - 92.96
30 - 92.60
50 - 90.98
cus alvarezii
Pyrolysis at
350oC for 2
The biochar did not
undergo any
blue 4
orange 16
2-3 30 180 60
of contact
mmol/g for RB4
Empty fruit
bunch (EFB)
at 800W for
30 min.
EFB particles were
treated chemically
by (FeCl3) before
pyrolysis. Flow of
nitrogen gas
provided iron oxide
formation to the
chemical treated
EFB. Modification
goals: biochar with
magnetic features
enable the dye to
be separated by
blue (MB)
25 120 120 Maximum
capacity of
96.68% (31.25
mg/g) for MB
capacity of
90.76% (32.36)
mg/g for
Empty fruit
bunch (EFB)
Pyrolysis at
The biochar did not
undergo any
blue (MB)
- 30 150 250 Dye removal of
91%, 90%, 49%
100, 200 and
300 mg/L
biochar has a
sorption of
55.25 mg/g.
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Pyrolysis at
50oC for 2
The biochar did not
undergo any
Congo red
dye (CR)
2-7 30 120 15 75-
80% dye
bones (CBB)
Pyrolysis at
500oC for 2
Powdered CBB
subjected to co-
precipitation with a
mixture of Fe3+ and
Fe2+ salts. The CBB
was added into a
solution containing
FeSO47H2O and
Modification goals:
biochar with
properties f
or rapid
sorption and a
e-B (RB)
(basic dye)
10 50 150 120 88.5% dye
removal for
40mgL-1. (36.2
96.5 mg/g of
RB was
adsorbed at pH
10 within 180
min and
reduced to
68.5 mg/g in
the presen
ce of
0.5 g NaCl.
Pulp and
sludge (PPS)
Pyrolysis at
108oC for 2
PPS soaked in a
O solution
and dried before
being pyrolyzed.
Modification goals:
Reduce porosity
and decrease in
pore volume as a
result of
impregnation that
will lead to a rapid
dye diffusion into
the active sites
when the particles
organically detach
from the biochar
into the solution
blue (MB)
12 - - 40 Impregnating
PPS with Fe2O3
sorbent by
g/L adsorbent
BC and NC
Pyrolysis at
500oC for 1
The biochar did not
undergo any
Congo red
violet (CV)
30 150 1400 maximum
Pyrolysis at
oC for 1
Best results
for the 800
oC biochar
The biochar did not
undergo any
7.5 60 10,000
51.89 removal
of dye
mg/L) for SCB
prepared at
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The sustainability of the textile industry should be addressed across all sectors from fashion designers,
manufacturers, product developers and the consumers. The process residuals as waste and wastewater
generated requires innovative and affordable technologies and processes for collection and reuse, recycle and
upcycle of textile waste (clothing and other textiles), for reducing the consumption of water, energy and
chemicals and for treatment of the textile wastewater both in treatment plants and in small dye house industries.
The environmental law for the dyeing effluent is in many cases very stringent and this necessitates the need for
efficient treatment methods that must follow Zero Liquid Discharge (ZLD) either in common or in non-common
treatment plants; however in practice due to the treatment costs it is not always practiced. In addition, even
when plants are set for the ZLD, they are still generating hundred tons of hazardous solid waste per day as sludge
(residual dyes and waste salts). Efforts should be made also on recovery of the dyes, and other organics from the
wastewater before their discharge on to the soil and water bodies, in addition to efficient water treatment by
combining novel hybrid membranes and nanotechnologies.
Tamil Nadu is in southern part of India and is engaged in textile processes especially the cotton textile industry.
Real textile wastewater effluent from dye houses located in Coimbatore, Tamil Nadu, southern India, was
examined for acid-dye removal from wastewater generated when dyeing silk filaments for production of soft silk
sarees. The used dye solution from the dye houses is often discharged to the drainage or into the environment
due to lack of affordable solutions. These dyes can potentially cause serious environmental damage and health.
In our study, optimal conditions were demonstrated for filtration followed by high dye adsorption onto pine
derived biochar (both in batch and column studies), and recommendations were suggested for reuse of the water
back to the dye houses and for recovery of the biochar post use.
Different types of biochar were effective in adsorption of dyes from the textile wastewater effluent. Parameters
that affect the process are temperature, rotation and mixing speed of the biochar with the dye in batch tests,
and reaction time. Another important parameter is the pH of the biochar-dye suspension. Basic environment (pH
higher than 7) was proven to be ideal for cationic dyes, where acidic environment (pH below 7) was proven to
be ideal for anionic and acid dyes, with the optimal pH being between 3-4. Different post-production
modifications to the biochar can increase the efficiency of the adsorption process and thus improve the entire
treatment process; however, the long-term use and reuse of the modified biochar should be monitored.
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... The textile industry is one of the largest consumers of dyes, accounting for 70% of its sector, generating nearly $1 trillion, accounting for 7% of global trade, and employing almost 35 M individuals globally (Mamane et al., 2020;Sonu et al., 2020). The textile industry produces the most wastewater, accounting for nearly half of all dye effluent worldwide (Farhana et al., 2022). ...
Rhodamine B is a toxic dye due to its carcinogenic, neurotoxic, and disease-causing properties. Appertaining to the removal of Rhodamine B, the adsorption with biomass residues adsorbent demonstrated positive results. The primary objective was to evaluate the feasibility of various adsorbents used throughout recent years to remove Rhodamine B dye from wastewater. Biomass residues and adsorbents as an alternative to activation have garnered considerable interest among researchers. Microbial enzymes and biomass eliminated Rhodamine B at approximately 76% and 90.1%. In contrast, the adsorption of white sugar using biomass residues, especially AC, achieved 98% in 12 min. Due to the zwitterionic forms of Rhodamine B, the adsorption process has a broad pH range (3–10). Gamhar leaves AC is one of the agriculture waste absorbents with an adsorption capacity of 1000 mg g⁻¹. The biomass residue adsorbents appeared to have a high potential for removing Rhodamine B from wastewater.
... Table 3 provides instances of biochar formation using activation and modification techniques. These procedures involve treating steam, bases, acids, carbonaceous materials, metal oxides, organic compounds, clay minerals, and microorganisms (Ahmad et al., 2019;Mamane et al., 2020;Mishra et al., 2021) . ...
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Biochar is a carbon-rich product obtained from the thermochemical conversion of biomass. Utilizing biochar is essential for enhancing economic viability and maintaining the ecology effectively. This work reviews the techniques for producing biochar from various lignocellulosic biomass sources. Pyrolysis technology for converting lignocellulosic biomass into biochar has emerged as a frontier research domain for pollutants removal. The effects of biomass feedstock parameters, production techniques, reaction conditions (temperature, heating rate, etc.), activation, and functional group modification are compared on biochar's physical and chemical properties. This review also focused on environmental applications in several domains, such as agriculture and wastewater treatment. Considering the extensive availability of feedstock, excellent physical/chemical surface properties, and inexpensive cost, biochar has a remarkable potential for removing water pollutants efficiently. Studying the evolution properties of biochar by in-situ or post-modification is of great significance for improving the utilization value of lignocellulosic biomass. Biochar is a valuable resource, yet its application necessitates additional research into its properties and structure, as well as the development of techniques to modify those factors.
... These colours have the potential to harm the environment and human health [52]. Effective filtration conditions were proven to remove the hazardous dyes followed by high dye adsorption onto pinederived biochar (both in batch and column tests), and recommendations for water reuse were made [53]. ...
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This review comprehensively describes biochar, the term which is gaining exponential attention nowadays. The technologies to convert the agriculture waste to biochar include slow pyrolysis, flash pyrolysis, and hydrothermal carbonization. Biochar production methods are based on batch processes and continuous processes. Biochar production processes and steps involved are also discussed. Different biochar reactors are also revived, including the continuous type of biochar reactor and microwave pyrolysis reactors. Kinetics of biochar, bio-oil, and syngas production is also revived briefly with kinetic equations. Uses of biochar are comprehensively revived and discussed, including advanced applications such as catalyst production, activated Carbon production, water treatment, soil amendment, etc. All biochar characterization methods are briefly described, including proximate analysis, ultimate analysis, physiochemical analysis, surface analysis, and molecular structure analysis. Factors affecting biochar production are revived in this article. Biochar yield from different crop waste s is tabulated with temperatures involved. Post-production processing methods of biochar are included in this review. The global biochar market and current status and opportunities are also revived, the data of biochar manufacturers in India are compiled. The utilization of biochar in agriculture is revived in two subcategories: the effect of biochar application on soil health and the effect of biochar application on crop yield. At last engineered or designed biochar concept is revived.
... Various methods for organic contaminant removal from wastewater have been investigated and reported in the literature. These include froth flotation, precipitation, flocculation-coagulation, reverse osmosis, membrane filtration, photodegradation, electrochemical destruction, irradiation-ozonization, Zn-Ferrite inorganic catalyst-assisted photo Fenton degradation, adsorption using nanoparticles and adsorption using commercial grade activated charcoal ( Bapat, 2020 ;Cuerda-Correa et al., 2020 ;Mamane et al., 2020 ). ...
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Water hyacinth (WH) is well-known as an invasive species that threatens aquatic biodiversity worldwide. Manual or physical removal of this substance from water is necessary to avoid secondary water pollution caused using chemically synthesized herbicides by its control, resulting in organic waste generation. Researchers recently recommended, among other things, this waste might be converted into adsorbents that can be used for the remediation of water resources, as well as other applications. This is critically important since clean water is still required in all aspects of life, regardless of its quality. The remediation approaches presented for the treatment of water supplies through the remediation of organic contaminants utilizing WH are discussed in this study. Research into the use of WH for phytoremediation and the removal of organic contaminants has been conducted in detail. It can be seen from this review that the overview of various works was more concerned with the removal of organic dyes from water than with any other topic. A study of the underlying mechanisms in the adsorption processes is presented in this context. Towards the end of the paper, it is suggested that future research into the use of WH to remediate water resources will aid in the water resource environmental management.
The fashion industry is now in the eye of the storm for what concerns sustainability because of the enormous impact that such a business area has on the environment. To exploit the full potential for circular economy implementation, the fashion industry requires urgent changes adapting much more conscientious business practices, driving consumers to change their perceptions and behaviours towards circular products and services. The renunciation of greenwashing practices and the use of strategy focused on regaining consumer’s trust will increase the positive sentiment towards the fashion brands. This work demonstrates to what extent greenwashing may jeopardise the fashion industry in addressing challenges related to the implementation of more sustainable circular economy in the context of designing with intention of recycle, reduction of by-products, lower energy consumption and wise purchase habits. This study provides guides for the fashion brands about the risks and gains related to the greenwashing practices and sustainable fashion industry. This study sketches also future research opportunities in more sustainable holistic approach of a products’ life cycle and how this can be translated into clear, transparent, or reliable certification schemes to prevent the misleading and dishonest marketing strategies helping the consumers to make a responsible choice.
The response surface methodology (RSM) is applied for predictive estimation and optimization of decolourization of safranine, a phenazine dye by a chemical oxidation process using iron(II) as homogeneous catalyst and chloramine B (CAB) as an oxidant in acid medium. All experiments were based on the statistical designs in order to develop the predictive regression models and for optimization. Four independent variables (temperature, catalyst, CAB and acid concentration) were chosen to optimize the decolourization of safranine. When variance was analyzed (ANOVA), values of R2 and adjusted R2 were 0.9618 and 0.9262, respectively. The data derived from the experiments were in alignment with a second order regression model. In order to achieve a maximum decolourization, the optimal settings were found to be 0.0178 M HClO4, 0.004 M CAB, 0.0016 M iron(II) and 43.1 ºC, respectively. Under optimal reaction conditions, effect of temperature (15, 25, 35, 45 ºC) on decolourization rate was studied. Data received were in congruence with the second order kinetics. Thermodynamic parameters were also computed for the decolourization process. Maximum percentage of decolourization of safranine was predicted and experimentally validated.
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In this study, we explored the adsorption potential of biochar derived from palm kernel shell (BC-PKS) as an affordable adsorbent for the removal of crystal violet from wastewater. Kinetics, equilibrium, and thermodynamics studies were carried out to evaluate the adsorption of crystal violet onto BC-PKS. The kinetics adsorption process followed the pseudo-second-order model, indicating that the rate of adsorption is principally controlled by chemisorption. The adsorption equilibrium data were better fitted by the Langmuir isotherm model with a determination coefficient of 0.954 and a maximum adsorption of 24.45 mg/g. Thermodynamics studies found the adsorption of crystal violet by BC-PKS to be endothermic with increasing randomness at the BC-PKS/crystal violet interface. The percentage removal and adsorption capacity increased with the pH of the solution, as the negative charges on the biochar surface at high pH enhance the electrostatic attraction between crystal violet molecules and BC-PKS. Increasing the BC-PKS dosage from 0.1 to 1.0 g increased percent removal and decreased the adsorption capacity of crystal violet onto BC-PKS. Therefore, biochar from agricultural by-products, i.e., palm kernel shell, can be cost-effective adsorbents for the removal of crystal violet from textile wastewater.
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The prospective utilization of bael shell (Aegle marmelos) as an agro-waste for the production of biochar was investigated along with its characterization and application for the abatement of hazardous aqueous Patent Blue (PB) dye solution. The sorptive removal of PB on bael shell biochar (BSB) was investigated under the following operational conditions: (pH, 2.7-10.4; biochar dosage, 2-12 g/L; and contact time, 0-60 min). The removal efficiency of PB by BSB in a batch adsorption experiment was 74% (pH 2.7 and 30 ± 5 • C). In addition, a clear relationship between the adsorption and pH of the solution was noticed and the proposed material recorded a maximum sorption capacity of 3.7 mg/g at a pH of 2.7. The adsorption of PB onto BSB was best explained by the pseudo-second order kinetic model (R 2 = 0.972), thereby asserting the predominant role of chemisorption. The active role of multiple surface-active functionalities present on BSB during PB sorption was elucidated with the help of Freundlich isotherm (R 2 = 0.968). Further, an adsorption mechanism was proposed by utilizing Fourier transform infrared spectroscopy (FTIR).
In this work, the occurrence of contaminants in drinking water sources was described in relation to their treatment options based on both conventional (e.g., coagulation-flocculation, sedimentation filtration, and chlorination) and advanced treatment techniques (e.g., membrane filtration, ozonation, and biofiltration). However, due to apparent drawbacks of these methods (e.g., formation of disinfection by-products (DBPs)), it is desirable to develop an alternative option for safe drinking water. In this respect, biochar is recognized as an effective candidate to resolve the limitations in treating common pollutants typically occurring in drinking water such as microbial contaminants, inorganic contaminants, heavy metals, volatile organic compounds (VOCs), pharmaceuticals and personal care products (PPCPs), and endocrine disrupting chemicals (EDCs). As biochar can exhibit different types of interactions with adsorbates, its sorption processes can be explained by diverse mechanisms, e.g., π-π electron donor-acceptor interactions, complexation, precipitation, H-bonding, and electrostatic attraction. In light of the attractive features of biochar (e.g., enhanced sorption properties, cost-effectiveness, and environmentally friendly nature), we offer in-depth discussion on biochar-based water treatment technologies for large-scale water purification operation. • Highlights • Occurrence of various contaminants in drinking water sources are discussed. • Human health impacts of exposure to drinking water contaminants are highlighted. • Performances and limitations of conventional and advanced water treatment technologies are discussed. • Potentials of pristine and modified biochars for drinking water purification are emphasized. • Feasibility and importance of biochar-based large-scale water treatment technologies are highlighted.
Synthetic dyes or colorants are key chemicals for various industries producing textiles, food, cosmetics, pharmaceutics, printer inks, leather, and plastics. Nowadays, the textile industry is the major consumer of dyes. The mass of synthetic colorants used by this industry is estimated at the level of 1 ÷ 3 × 105 tons, in comparison with the total annual consumption of around 7 × 105 tons worldwide. Synthetic dyes are relatively easy to detect but difficult to eliminate from wastewater and surface water ecosystems because of their aromatic chemical structure. It should be highlighted that the relatively high stability of synthetic dyes leads to health and ecological concerns due to their toxic, mutagenic, and carcinogenic nature. Currently, removal of such chemicals from wastewater involves various techniques, including flocculation/coagulation, precipitation, photocatalytic degradation, biological oxidation, ion exchange, adsorption, and membrane filtration. In this review, a number of classical and modern technologies for synthetic dye removal from industry-originated wastewater were summarized and discussed. There is an increasing interest in the application of waste organic materials (e.g., compounds extracted from orange bagasse, fungus biosorbent, or green algal biomasses) as effective, low-cost, and ecologically friendly sorbents. Moreover, a number of dye removal processes are based on newly discovered carbon nanomaterials (carbon nanotubes and graphene as well as their derivatives).
In this work, the biochar adsorbent carboxymethyl cellulose (CMC), was prepared from the pyrolysis (600 °C, 120 min) of chicken manure for the removal of methyl orange (MO) from aqueous solution, and its physicochemical properties were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR). The experimental parameters including agitation speed, initial solution pH, biochar dosage and contact time on the adsorption properties of MO from aqueous solution onto CMC were investigated in batch experiments. The kinetic adsorption of different initial concentration could be accurately described by the pseudo-second-order model and the overall rate process was apparently influenced by external mass transfer and intra-particle diffusion. Furthermore, the Langmuir isotherm model showed a better fit with equilibrium data (R2> 0.99), with the maximum adsorption capacity of 39.47 mg·g-1at 25 °C. Moreover, the thermodynamic parameters indicated that the adsorption of MO onto CMC was a spontaneous and endothermic process. The results of this study indicated that CMC could be used as a promising biomass adsorbent material for aqueous solutions containing MO.
This two-volume work is an effort to provide a common platform to environmental engineers, microbiologists, chemical scientists, plant physiologists and molecular biologists working with a common aim of sustainable solutions to varied environmental contamination issues. Chapters explore biological and non-biological strategies to minimize environmental pollution. Highly readable entries attempt to close the knowledge gap between plant - microbial associations and environmental remediation. Volume 2 focuses on the non-biological/chemical approaches for the cleanup of contaminated soils. Important concepts such as the role of metallic iron in the decontamination of hexavalent chromium polluted waters are highlighted; in addition, nanoscale materials and electrochemical approaches used in water and soil remediation are discussed; and the synthesis and characterization of cation composite exchange material and its application in removing toxic metals are elaborated in detail. Readers will also discover the major advances in the remediation of environmental pollutants by adsorption technologies. © Springer International Publishing AG 2017. All rights reserved.