Furfural Removal from Refinery Wastewater by Adsorption on Commercial Activated Carbon

Furfural is a toxic aromatic aldehyde that can cause severe environmental problems, especially the wastewater discharge from petroleum refinery units. The effect of adsorption variables, which include time (30-240) min, initial concentration of furfural (40-5080) mg/l, and amount of adsorbent material (10, 15, and 20 g\250 ml). The commercial activated carbon was investigated in a batch process in order to obtain the maximum furfural removal from wastewater. The results obtained from the experimental investigations showed that furfural removal increases with the increasing adsorbent material and decreases with increasing furfural concentration. Best Furfural removal efficiency was obtained at pH value equal 7.0, agitation speed 150 rpm, contact time 240 minutes. Chemical adsorption takes place when increasing temperature adsorption capacity increases. The best solvent used to regenerate activated carbon was ethanol 50 wt%. Ethanol has been used in industrial applications due to its low cost and relatively eco-friendly solvent. The laboratory experiments were done, and the sump drum O3D4, D-303 site was chosen to execute the project. The maximum contamination in the furfural was 100 ppm. The dimension of the polluted area in the sump drum (O3D4, D-303) was 20.3, 45 m2. The amount of activated carbon used 327, 726.3 kg


Introduction
Petroleum refineries are confrontation pollution problems linked with the accidental losses of furfural. This forms an economical loss as well as environmental hazards. Furfural is a toxic aromatic aldehyde with the chemical formula C 4 H 3 OCHO [1]. It is pale yellow or colorless oily liquid and turns into brown or red in the presence of air or light. Human exposure has been classified as a hazardous material that can damage the lungs, liver, kidneys and spleen. The permissible exposure limit (PEL) for the furfural is 5 ppm [2].
Furfural is an ideal solvent used to separate desired and unwanted components in petroleum derivatives. It has the following basic properties: Good solvent for extracting undesirable components as well as highly selective for desirable components, easy to be recovered does not react chemically with the components of oil, and it is not toxic industrial, when used has a high degree of stability [3].
Furfural has got main applications like in lube oil refining, in pharmaceuticals, and in the manufacture of phenolic resins. It is widely used in the solvent extraction processes of the petroleum refineries as a solvent extracting. It is also used as a chemical intermediate, weed killer, fungicide, and also as a flavoring agent. Sulfite pulping processes used in the pulp and paper industry are a major source of furfural contamination. Synthetic rubber plant wastewater has been found to have 1.7 g/l furfural. Leakage of furfural not only causes a pollution problem but also constitutes a sizable economic loss [4].
Activated carbons are among the best adsorbents utilized for adsorption processes. Activated carbons possess high surface area per unit mass and exhibit high adsorption capacities for many adsorbates. Essentially, the structure of Activated carbons contains pores which are arranged by the International Union of Pure and Applied Chemistry (IUPAC, 1972) order into three groups: micropores (pore measure < 2nm), mesopores (pore estimate 2-50 nm) and macropores (pore estimate > 50 nm) [5]. . Concept of Adsorption, in adsorption theory, The solid material that provides the surface for adsorption is referred to as adsorbent; the species that will be adsorbed are named adsorbate [6]. Adsorption occurs due to unsaturated and unbalanced molecular forces on the surface of the solid [7]. When molecules move from the liquid phase to the solid surface. Adsorbed species can be released from the surface and transferred back into the liquid phase. This reverse process is referred to as desorption [8].
The aim of present work removal of furfural from petroleum refinery wastewater by commercial activated carbon and Make regeneration for activated carbon and recovery of furfural.

Material and methods
-Materials: Adsorbent commercial activated carbon supplied by (Unicarbo, Italian, Lmt. Co.) Adsorbate Furfural was used as an adsorbate; it has synonyms of (2furaldehycle, Furyl and 2 Furyl methanol), Tables (1,2) show the chemical and physical properties of furfural and ethanol respectively [9].  These experiments were summarized in Table (3) including the following variables (initial furfural concentrations, amount of adsorbent (dose) and temperature) with constant PH, agitation speed and particle size.

Theory/Calculation
The variation of furfural concentration in the aqueous solution due to adsorb by commercial activated carbon was determined calorimetric at wavelength (000nm) by UV-Visible DR5000 Spectrophotometer. The percent removal of furfural (Y R ) due to adsorption process was calculated according the equation: ……………………… (1) ……………………… (2) Where C o and Ce the initial and equipoise concentration of furfural in the aqueous solution.
q e adsorption capacity and V the volume of beaker W the weight of amount activated carbon [10] 3. Results and Discussion: The important properties of activated carbon are surface area and pore volume.

Effect of contact time, the initial concentration of furfural, the amount adsorbent.
The removal percent of furfural at different contact time from 30 to 240 minute. Figure  increasing time until reach to equilibrium [12] .The removal of furfural at different amount of adsorbent shown in Figure (3). Due to increase the amount of adsorbent material the surface area will increase therefore the removal percent increasing [13].

Effect of temperature.
The temperature is the factor that greatly affects the adsorption capacity and the rate of adsorption. During the study for the adsorption of furfural on activated carbon, when increasing the temperature from 35 o C to 50 o C this will led to a increase in adsorption capacity as shown in Figure (5) . That means adsorption is chemical so it is not easy to adsorb furfural ions with pure water [14]. Removal percent increases with increase temperature as shown in Figure (4), but In general the temperature does not affect significant.

Regeneration of activated carbon and recovery furfural
To evaluate the regeneration efficiency, adsorption batch tests were performed with regenerated adsorbents after regeneration, and the adsorption capacity of regenerated adsorbents was compared with the fresh adsorbents [19].

Condition of Desorption Tests
Tables (6) and (7) shows the condition of the desorption tests, in which activated carbon were contacted with pure water at different temperature. The content of furfural desorbed into the regenerates was analyzed by UV-Vis spectrophotometer after desorption tests.

Desorption by Pure Water
DI water was first utilized in the desorption tests to desorb furfural from the activated carbon at different temperature. The results of UV spectra of furfural desorbed from activated carbon into water show the pure water not can adsorb furfural because the type of adsorption is chemical so we cannot use pure water as regenerates [20] as shown in Figure (  wt%. Ethanol has advantages in industry application due to its lower cost and relative ecofriendliness [21].

Oil-2
In a single operation in case maximum pollution (100 ppm) the cost of furfural lost (4519.2 $). We used activated carbon cost (528 $) for three treatment pollution also the cost of ethanol used for regeneration of activated carbon and recovery of furfural is (3060.8 $) after that we can used activated carbon, the equation will become [22]:

Conclusions
According to the results obtained from this study, the following conclusions are obtained: 1-Activated carbon with BET surface area of 950 m 2 ∕ g and iodine number of 850 m 2 \g, so it is having high ability to adsorb furfural.