Functions and the quality of wetlands have adversely been affected by factors such deforestation, fertilizers, and

pesticides. Pollution caused by phosphates and nitrites affect aquatic life as these anions have serious side effects

even at low levels. Wetlands are vital as they play a role to supply water used for domestic and farming. Pollution

in wetlands leads to eutrophication, reduces dissolved oxygen among others. The objective of the study was to

compare adsorption capacities of silica molybdate and diazonium silica with activated carbon. Silica molybdate

was prepared by chlorination of raw silica then aminating using ethylenediamine (EDA) followed by addition

of sodium molybdate to aminated silica. Diazonium silica was prepared by reacting aminated silica with sodium

nitrite. FT-IR spectroscopy was used characterize the prepared adsorbents. The adsorption capacities of the

adsorbents was compared with activated carbon. The adsorbents were used to remove PO

chain azo (N=N) group. Biosorption isotherm fitted well in Freundlich isotherm model for adsorption of

phosphates. Biosorption isotherm model that fitted well for adsorption of nitrites was Langmuir model. For

sorption of phosphates pseudo-first order kinetics model was best obeyed while for adsorption of nitrites pseudo-

second order kinetic model was best obeyed. Adsorption capacity of phosphate was 194.53mg/g and 6.892 mg/g

for nitrites as compared to activated carbon which was 8.241 mg/g for phosphates and 0.07985 mg/g for nitrites.

For adsorption of nitrites biosorption isotherm fitted well in Langmuir model. For sorption of phosphates pseudo-

first order kinetics model was best obeyed while for adsorption of nitrites pseudo-second order kinetic model

was best obeyed. Adsorption efficiency of phosphates and nitrites in wetland waters, were 55.9% for phosphates

and 44.7% for nitrites.Results obtained indicate that silica molybdate and diazonium silica are better adsorbents

water table is usually at or near the surface or the land is covered by shallow water [2]. Wetland was also referred

to as areas of fen marsh, peat land or water whether natural or temporary with water being static or flowing,

brackish, fresh or salt including areas of marine water, the depth of which at low tides does not exceed 6 meters

[3]. Industries target water bodies by discharging industrial effluents to them leading to pollution. Waste water

is harmful not only to aquatic life but also harmful to human life. [4]. Pollution in the environment should be

handled in a special way as it is a serious matter affecting many organisms. Water is the mostly adversely affected

environmental resources [5]. Pollution in the environment is brought by a number of pollutants such as organic

and inorganic pollutants, heavy metals and organic micropollutants (OMPs). Municipal sewage, electroplating

effluent, and breeding wastewater are some of the toxins that are released into the environment

materials which contain carbon such as; coconut shells, bones, pecan, lignite shells, waste water treatment

sludge, petroleum-based materials, pulp mill, sugar, black ash and wood among others. These materials are

processed to improve their adsorption properties. This is achieved by exposing materials at high temperature to

remove solid mass and create pores where removed mass was located initially. The well-developed pore network

is a common property of activated carbons and other types of carbon adsorbents produced in a similar way [7]).

Materials with chemical properties and contain nanoscale features have a great potential for application in water

treatment. Activated carbon is commonly used as point-of-use (POU) devices, where many commercial systems

apply this material at home [8]. More research work has been conducted to improve the efficiency of activated

carbon by modifying their specific properties so that carbon can develop affinity for the specific [9].

phosphates [11]. United State Environmental Protection Agency set the maximum contaminant level for

small fraction of phosphate can be removed by precipitation. Biological treatment involves use of biochemical

process to remove phosphates from waste water. There are more phosphates in water than what biochemical

technology can handle. Primary and secondary waste water treatment can remove about 20-30% of phosphorous.

Preferred water contains phosphorous content high above the regulated standard limits. Therefore, there is need

to come up with an adsorbent which can lower the levels of phosphates in wetland waters [13]. Nitrite ions are

termed as wide spread contaminants established in aqueous environment. Nitrite ions are a significant indicator

of the quality of natural waters. Increase in the levels of nitrite ions in ground or surface waters is caused by

agricultural activities like use of fertilizers. Another source of nitrite ions is from industrial effluents discharged

acceptable concentration of NO

to be 3mg/[15].

A variety of functional groups such as thiols, propyl groups, phenyl groups, vinyl and amines have been

introduced into silica matrices. The mesoporous materials functionalized by these groups are applied mostly in

heavy metal adsorption. [16].The most explored functional group to increase adsorption capacity is the amino

group. High binding affinity for metal ions and anions by diethylenetriamine (DETA) is caused by the

availability of primary and secondary amine groups in its structure. Grafting various substrates using DETA has

improved their chemical and physical properties [17].

stirring with magnetic stirrer. 1.5g of phosphorous pentachloride (PCl

) was added dropwise to the raw silica

suspended in DMF. The mixture was refluxed for 2hrs, filtered and washed with deionized water then dried

under vacuum at 70℃ for 24hrs. The second step involved the amination of chlorinated silica. 5.0g of chlorinated

silica was reacted directly with 25ml ethylenediamine. The resulting mixture was filtered, washed and dried in

a desiccator for 48hrs. The last step involved grafting of molybdate to the aminated silica. 1.0g of aminated silica

was mixed with 1.0g of sodium molybdate suspended in 25ml DMF. The resulting solution was refluxed for

3hrs at 80℃. The resulting mixture was filtered by vacuum filtration, washed and dried in the desiccator for

48hrs.

immediately. The precipitate was allowed to stand for 20 minutes with frequent shaking ensuring that the

temperature did not exceed 20℃. Yellow diazonium silica was filtered on a Buchner funnel. The residue was

washed with 100ml deionized water and dried at room temperature.

Characterization was done for raw silica (RS), chlorinated silica (CS), aminated silica (AS), silica molybdate

(SM) and diazonium silica (DS) using FT-IR spectroscopy. The interactions involving electromagnetic (EM)

fields in the infrared region (IR) and matter were studied using FT-IR spectroscopy [19]. A mass of 1.0 mg of

32 each sample of RS, CS, AS, SM and DS was mixed thoroughly with 50.0mg of potassium bromide (KBr).

Pellets were formed by grinding the mixture at vacuum. Obtained pellets were placed into FT-IR analysis

machine. Adsorption spectra of the adsorbent s were determined in a wavelength range 4000cm

to 400cm

[20].

throughout the experimental test. Preparation of phosphates solutions was done daily to avoid possible

precipitation of phosphate species. HCl and NaOH solutions 5%v/v were used to regulate the pH. The absorbance

of each phosphate solution was measured using UV-Vis spectrophotometer at maximum wavelength of 542 nm.

A calibration curve was plotted between absorbance against concentration of phosphates. Beer lambert law

equation was used to determine the molar absorptivity.

A = Σlc Equation 2.1

Where absorbance is represented by A, molar absorptivity is given by Σ (mol

that contains the sample L (cm) and the concentration of phosphate ions in the solution is given by c (mg/l) [21]

verses ce as shown in figure 3.1 of silica molybdate showed that the adsorption process obeyed the Langmuir

isotherm model according to the correlation coefficient value R

, Qmax and b which were obtained from the

slope and the intercept respectively. The essential features of Langmuir isotherm is expressed in terms of a

dimensionless constant separation factor or equilibrium parameter Rl expressed as Rl = 1/ (1+b.co) [33]. The

expression of Freundlich isotherm encompasses the exponential distribution of active sites and the surface

heterogeneity. The constant Kf and nf numerical values were determined from the intercept and slopes of

respective plots. Relative adsorption capacity of the adsorbent is indicated by the constant Kf relating to the

bonding energy referred to as adsorption distribution coefficient. This value represents the quantity of the metal

ions adsorbed in the adsorbent at equilibrium (Muhammad et al., 2012). Heterogeity factor is known as nf.

The sorption equilibrium is frequently described using the Langmuir equation. The Langmuir isotherm model

assumes that the uptake of metal anions takes place on the homogeneous surface using monolayer adsorption

where there is no interaction between the adsorbed ions. The model also assumes that all the surface sites are

alike and can accommodate one adsorbed molecule. Another assumption is that the adsorption process is

reversible and the adsorbed molecule cannot migrate across the surface or interact with the neighboring

molecule. In order to get the equilibrium data, the initial concentrations of nitrites ions were varied keeping the

0.97029 as illustrated in table 3.2. shows that there is a linear relationship or correlation [34].

Freundlich model is interpreted as the sorption of heterogeneous surface. It is assumed that the stronger binding

sites are occupied first and the binding strength decreases as the degree of occupation site increases. Freundlich

capacity and 1/n was found to be 0.2676 for intensity of adsorption. The correlation coefficient of Freundlich

model was 0.89511 as illustrated in table 3.1 In this study Langmuir model was best fit isotherm for adsorption

of nitrites ions on diazonium silica.

Table 3.1 shows the results of Langmuir and Freundlich isotherms for phosphates and nitrites adsorption

capacities