College Papers

Intorduction are separated from oxyhumolite they showed a

                                                 Intorduction

Humic
substances play an vital role in nature. They can bind to heavy metal ions, which
are characterized by high toxicity and the ability to accumulate in the
environment The typical dark coloration
of these substances increases heat retention by soils helping in seed
germination. They also elevate the buffering and cation exchan One of the most
characteristic properties of humic substances is their adsorption ability and
in this way, they can influence the effectiveness of regeneration and
purification processes in soil and aqueous systems. Hence, the immobilization
or removal of toxic metals is a research goal as well as an industrial task ge capacities of soils Humic
substances are popular for their high adsorption efficiency 1–4. Humic substances also interact with oxides,
hydroxides, minerals and organic compounds to form compounds, which are soluble
or insoluble in water, with different chemical and biological stabilities
(Schnitzer, 1986). The formation of metal complexes and chelates with low
solubilities, from the reaction between soil organic matter and metals, reduces
the probability of a toxic metal contaminate the groundwater (Tan, 1992).

 They can make bond with heavy metal ions,
which have the high toxic rates and they have the ability to collect and mix in
the atmosphere. Process starts regeneration in the soil and they can affect the
aqueous ecosystems 5–7. Therefore, the inactivation or excretion of these poisonous
substances is the key work of research as well as an economic task. A
profitable and environmentally-friendly method is the use of technology of
sorption founded on the use of sorbents composed from some bio-material 8,9.

When
humic acids, as the most efficient ingredients are used as an adsorbent for
metal ions, their effect and sorption capacity greatly increased 2. When we
compare the humic acids of different availabilities like natural and
commercial, it shows that the industrial humic acids show a very high sorption
capacity and a low degree of desorption 6, 12. While humic acids are
separated from oxyhumolite they showed a lower sorption capacity in comparison
with humic soil-derivatives of humic acids 13.

Connections between
humic acids and metal ions have a complex nature given by their heterogeneous,
poly-electrolyte, and poly-dispersive character. Metal ions can attach with
humic acids in different methods; due to the Wander Waal’s weak forces, highly
negative anions attraction etc result in the formation of other functional
groups 1, 2, 4, 7, 14–16. Due to the heterogeneous character of humic acids and
their partial solubility in water, there is a possibility of formation of
organic and inorganic mixtures of these metallic ions and other contaminants
4, 17–21. Humic acids of low molecular weight had the highest sorption
capacity than those of high molecular weight or un-fractionated humic material
13. It was found that the binding of metals to humic acids depends on their
character. The sorption capacity of humic acids for some metals is much higher
than their possibilities given by the content of functional groups. Metal ions
are attached to humic acids by different strengths and particular metals can
exist in humic material in various fractions 4, 22–26.

Due to the toxic effects of metal ions their removal
from aqueous ecosystems is necessary. In this regard different methods were
applied including precipitation, evaporation, electro-deposition, ion exchange,
membrane separation, coagulation etc 24-26. But these methods are expensive
and having some disadvantages like secondary pollution. Therefore, we are
applying commercially available humic acid as an adsorbent to remove metal ions
from aqueous solutions.