Removal of Colour From Dyes in

Water and Wastewater Using Leaves

of Plants as Adsorbents:

A Review of Pre-treatment Methods

Nadirah Ismail

Chemistry Department, Faculty of Science

Universiti Teknologi Malaysia

IWA

Young Water Professionals 2015

William Henry Perkins (1838–1907) Accidently discovered the first

synthetic dye (at 18 y.o)

Aniline purple

From chemicals derived from coal tar

From this grew the highly innovative chemical industry of synthetic dyestuffs

Definition

• Coloured substances that when applied to fibers, give them a permanent colour which is able to resist fading upon exposure to sweat, light, water, chemicals, oxidizing agents and microbial attack.

Characteristics

• Synthetic origin

• Complex aromatic structure

• Stable in the environment

• Metabolites are toxic

• Threat to environment and organisms

The Technologies

Treatment methods for textile effluents

Chemical methods Physical methods Biological methods

oxidation ozonationFiltration

Coagulation/

flocculation

adsorption

microbes

enzymes

Adsorption

Accumulation of the molecular species at the

surface rather than in the bulk of the solid or liquid is termed as adsorption.

The phenomenon of attracting and retaining the molecules of a substance on the surface of a liquid or a solid resulting into a higher concentration of the molecules on the surface is called adsorption.

A chemical process that takes place when adsorbateaccumulates on the surface of a solid (adsorbent), forming a molecular or atomic film.

It is a surface phenomenon.

Simplest

Low capital and operating costs

Rapid kinetics of adsorption and desorption

No sludge production

Can have good physical properties

Adsorbents are easily available

Activated Carbon

Well

established

Capable to

adsorb various

organics and

metals Porous

structure

High specific

surface area =

Large sorption

capacities*BUT, activated carbon for

commercial scale pollutant removal is

quite expensive!

Alternative adsorbents

“Depleting natural resources, growing environmental awareness and economic considerations are the major driving forces to utilize renewable resources such as biomass for various applications”

(Narendra Reddy & Yiqi Yang, Biofibers from agricultural byproducts for industrial applications, 2005)

Low cost alternative adsorbent

Originated from agricultural / domestic/ industrial waste.

Lignocellulosic wastes: plant biomass wastes that are consisted of cellulose, hemicelluloses and lignin.

Such as sawdust, grasses, stalks, nutshells, bagasse, leaves, and peelings.

Alternative AdsorbentsBanana stalk Peanut hull Plum kernels Mango seed

kernel

Coconut husk Neem leaf powder

Sugarcane dust

Tea waste

Rice hull Corn cob Sago waste Degreased coffee beans

Banana peel Duckweed Sugar beet pulp

Rice bran

Orange peel Apricotstone

Lemon peel Soybean hull

Guava leaf powder

Sunflower stalks

Jute stick Bamboo dust

Almond shell Cotton stalks

Raw barley straw

Hazelnut shell Rattan sawdust

Durian shell

Malachite

green

Crystal

violet

Methylene

blue

Nirgudi leaf,

Kammoni leaf,

Pineapple leaf

Mangifera Indica (Mango)

leaf, Calotropis procera

leaf

Gulmohar leaf,

Posidonia oceanica

leaf, Pineapple leaf

Pineapple

leaf

Mangifera

Indica

Calotropis

procera

Posidonia

oceanica

Application of plant leaf waste as biosorbent

X-ray Diffraction (XRD)

Scanning Electron Microscopy (SEM)

Surface area, pore size distribution

Fourier transform infrared

spectroscopy (FTIR)

Tools

Characterization of lignocellulosic materials

Physical treatment

WASH – DRY – CRUSH - SIEVE

Pre-treatment methods

Chemical pretreatment

FormaldehydeSulphuric

acid

Hydrochloric acid

Nitric acid

Sodium hydroxide

Formaldehyde has

been applied to

Sargassum binderi

to avoid organic

leaching that may

lead to secondary

pollution that might

devastate the

biosorption process

(Pei et al., 2009).

The chemical

treatments

enhanced the

adsorption kinetics

of Reactive Red 228

compared to

untreated Posidonia

oceanica (Ncibi et al.,

2007).

In the case of

Posidonia oceanica,

four types of chemical

treatments were

introduced i.e.

modification with 0.2

M nitric acid, 0.2 M

phosphoric acid,

sodium hypochloride

and 30% (v/v)

hydrogen peroxide

(Ncibi et al., 2007).

With chemical modification, adsorbent will experience good enhancements in pores.

When tea waste being treated with 0.5M NaOH, gap between pores like honeycomb shape was observed under scanning electron microscope (Nasuha and Hameed, 2011).

COVERED WITH MB

Physicochemical pre-treatments Another activation route that could give improved leaves’

pore structure

Involves the chemical agents such as alkali and mechanical actions.

Milling or extrusion of lignocellulosic biomass with the aid of alkali.

Mainly to destroy lignin structure

(d)

Wash

Dry

Grind & Sieve

Chemical treatment of adsorbent

Methanol to remove inorganic and organic matter from the surface of sorbents.

Deionizedwater

Acid treatment

Methanol

Adsorption

experiments

Adsorbent saturated

with dye

(Reactive Red 198)

Untreated leaves has relatively smooth surface while the physico-chemically treated leaves exhibits rougher surfaces.

Therefore, was proved to be a good activating agent to develop high surface area adsorbent

Lignocellulosic materials

Adsorption

pH of adsorbate

Adsorbent Dosage

Contact time

Factors affecting dye

adsorption onto adsorbent

High solution pH solution results in an increase in the percentage of cationic dye removal because the positive charge on the solution interface will decrease and the adsorbent surface appears negatively charged.

At higher solution pH, electrostatic repulsion is found between the negatively charged surface and dye molecules, thus decreasing the adsorption capacity and percentage removal of anionic dyes

pHLow pH solution results in an increase in the percentage of anionic dye removal because of the electrostatic attraction between anionic dye and the positive surface charge of the adsorbent

pH

In general, the dye removal percentage is increasing with the increase of the adsorbent dosage

When excess adsorbent dosage is used, a significant portion of the adsorption sites remain unsaturated. This obviously leads to low specific adsorption capacity.

DosageWhen the adsorbent dosage was lowered, the number of active sites saturated with dyes increased; therefore, specific uptake also increased

Dosage

At higher contact time, the rate of adsorption decreases, gradually leading to equilibrium due to decrease in total adsorbent surface area and less available binding sites

The decrease in dye removal with time may be due to aggregation of the dye molecules around the adsorbent particles.

Time

Plant leaves-based adsorbent offers many attractive features such as outstanding

adsorption capacity for many dyes, low in costing and environmental friendly.

FUTURE RESEARCH: Investigation of these materials with real industrial effluents,

recovery of used plant leaves-based adsorbent, regeneration study and

continuous flow study.

It offers significant advantages over currently available adsorbent and in

addition contribute to agricultural waste minimization strategy.

Conclusions

Thank You