Ion-exchange processes have been wi

Ion-exchange processes have been widely used to remove heavy
metals from wastewater due to their many advantages, such as high
treatment capacity, high removal efficiency and fast kinetics (Kang
et al., 2004). Ion-exchange resin, either synthetic or natural solid
resin, has the specific ability to exchange its cations with the metals
in the wastewater. Among the materials used in ion-exchange
processes, synthetic resins are commonly preferred as they are
effective to nearly remove the heavy metals from the solution
(Alyüz and Veli, 2009).
The most common cation exchangers are strongly acidic resins
with sulfonic acid groups (eSO3H) and weakly acid resins with
carboxylic acid groups (eCOOH). Hydrogen ions in the sulfonic
group or carboxylic group of the resin can serve as exchangeable
ions with metal cations. As the solution containing heavy metal
passes through the cations column, metal ions are exchanged for
the hydrogen ions on the resin with the following ion-exchange
process:
nReSO3H þ Mnþ/


ReSO
3

n
Mnþ þ nHþ (4)
nR COOH þ Mnþ/


R COO

n
Mnþ þ nHþ (5)
The uptake of heavy metal ions by ion-exchange resins is rather
affected by certain variables such as pH, temperature, initial metal
concentration and contact time (Gode and Pehlivan, 2006). Ionic
charge also plays an important role in ion-exchange process. The
influence of ionic charge on the removal of Ce4þ, Fe3þ and Pb2þ
from aqueous systems by cation-exchange resin purolite C100 was
tested by Abo-Farha et al. (2009). They found that the metal ions
adsorption sequence can be given as Ce4þ > Fe3þ > Pb2þ. Similar
results for Co2þ, Ni2þ and Cr3þ on an Amberlite IRN-77 cationexchange
resin were previously obtained by Kang et al. (2004).
Besides synthetic resins, natural zeolites, naturally occurring
silicate minerals, have been widely used to remove heavy metal
from aqueous solutions due to their low cost and high abundance.
Many researchers have demonstrated that zeolites
exhibit good cation-exchange capacities for heavy metal ions
under different experimental conditions (Motsi et al., 2009;
Ostroski et al., 2009; Taffarel and Rubio, 2009). Clinoptilolite is
one of the most frequently studied natural zeolites that have
received extensive attention due to its selectivity for heavy
metals. Table 2 shows the efficiency of clinoptilolite for
removing heavy metal ions.
Recently, some researchers reported that the surface of clinoptilolite
loaded with amorphous Fe-oxide species would significantly
improve the exchange capacity of clinoptilolite (Doula and
Dimirkou, 2008; Doula, 2009). Doula (2009) employed
clinoptiloliteeFe system to simultaneously remove Cu, Mn and Zn
from drinking water. He found that the system has very large metal
adsorption capacity and for most of the cases the treated water
samples were suitable for human consumption or agricultural use.
Though there are many reports on the use of zeolites and
montmorillonites as ion-exchange resin to remove heavy metal,
they are limited at present compared with the synthetic resins. And
the application of zeolites is on the laboratory experiments scale.
More work is needed for the application of zeolites at an industrial
scale.
2.3.

ผลลัพธ์ (แอฟริกา) 1:

Ione prosesse is wyd gebruik word om te verwyder Heavy
Metals uit afvalwater Weens hul baie voordele, soos High
Behandeling kapasiteit, doeltreffendheid en 'n vinnige High Verwydering Kinetics (Kang
et al., 2 004). Ione hars, óf sintetiese of natuurlike Solid
hars, het die spesifieke vermoë om sy katione te ruil met die Metals
in die afvalwater. Onder die materiaal gebruik in ione
prosesse, is sintetiese harse algemeen Voorkeur soos hulle is
effektief tot byna Verwyder die Heavy Metals uit die oplossing
(Alyüz en Veli, 2009).
Die mees algemene katioonuitruilers is sterk suur harsen
met sulfonic suur groepe (. ESO3H) en swak suur harsen met
karboksielsuurgroep (ECOOH). Waterstofione in die sulfonic
of karboksielgroep Groep van die hars kan dien as uitruilbare
katione ione met Metal. As die oplossing wat Heavy Metal
gaan deur die kolom katione word metaalione verruil vir
die waterstofione op die hars met die volgende ione
Proses:
NReSO3H Þ maand verdien
/?
Lok
3 N maand verdien Þ NHþ (4) nR COOH Þ maand verdien /. ? R COO N maand verdien Þ NHþ (5) Die opname van Heavy Metal ione deur ioonuitruiling harsen is eerder wat geraak word deur sekere veranderlikes soos pH, temperatuur, Aanvanklike Metal en konsentrasie Kontaktyd (Gode en Pehlivan, 2006). Ioniese lading speel ook 'n belangrike rol in die ione te verwerk. Die invloed van Ioniese lading op die opheffing van die Ce4þ, Fe3þ en Pb2þ van waterige stelsels deur katioon-Exchange Purolite C100 hars is getoets deur Abo-Farha et al. (2009). Metaalione Hulle het bevind dat die adsorpsie Volgorde gegee kan word as Ce4þ> Fe3þ> Pb2þ. Soortgelyke resultate vir Co2þ, Ni2þ en Cr3þ op 'n Amberlite IRN-77 Cationexchange hars verkry deur Kang et al voorheen. (2004). Behalwe sintetiese harse, Natuurlike zeoliete, wat natuurlik voorkom silikaatminerale, is wyd gebruik word om te verwyder Heavy Metal van waterige oplossings gevolg van hul lae koste en hoë oorvloed. Baie navorsers het getoon dat zeoliete toon goeie katioon-Exchange vermoëns vir swaar. metaalione onder verskillende toestande eksperimentele (Motsi et al, die 2009;.. Ostroski et al, die 2009; Taffarel en Rubio, die 2009). Clinoptiloliet is een van die mees algemene bestudeer Natuurlike zeoliete wat intensiewe aandag ontvang Weens sy selektiwiteit vir Heavy Metals. Table 2 toon die doeltreffendheid van clinoptiloliet vir die verwydering van Heavy Metal ione. Onlangs het navorsers berig dat die oppervlak van clinoptiloliet Sommige Loaded met amorfe Fe-oksied spesies aansienlik sal verbeter die vermoë van clinoptiloliet Exchange (doula en Dimirkou, die 2008; doula, 2009). Doula (2 009) in diens gelyktydig ClinoptiloliteeFe System te verwyder Cu, Mn en Zn van drinkwater. Hy het gevind dat die stelsel het 'n baie groot Metal adsorpsie kapasiteit en vir die meeste van die gevalle is die behandelde water monsters geskik vir menslike verbruik of Agricultural gebruik. Hoewel daar is baie verslae oor die gebruik van zeoliete en Montmorillonites as ione hars te verwyder swaar. metaal, is hulle op die oomblik beperk in vergelyking met die sintetiese harse. En die Aansoek Laboratory eksperimente van zeoliete is op die skaal. Meer werk is nodig vir die toepassing van zeoliete op 'n Industrial skaal. 2.3.