Investigation of the elimination of Acid Red 74 from wastewater by the rounded cones of Cupressus arizonica

Water is one of the most important factors for the survival of human life and living creatures. Water pollution is a big threat and a worldwide concern. Some of the most hazardous pollutants of water are different dyes which enter water sources from various industries like textile and leather. Researchers are trying to prevent this from happening as far as possible. Organic colors are an important group of dyes. Because in addition to contamination, they reduce the penetration of sunlight into the water and threaten the life of aquatic plants by disrupting photosynthesis. Organic colors are almost strong and resistant to biological degradation [1]. When entering the human body, they can be regarded as a potential or probable carcinogen and totally endangers human life and environment [2]. The common decolorization methods for synthetic dyes are adsorption, coagulation, flocculation, microbiological or enzymatic decomposition, membrane filtration, ion-exchange, oxidation and advanced oxidation [3]. Among all these methods, adsorption has its own advantages and can be effective for wastewater treatment [4]. Some of the agricultural products which have few or no special usage can be utilized as cheap adsorbents for removal of dyes from water. They are inexpensive, freely available, abundant, having a simple application, high efficiency and green chemistry. [5] Cupressus arizonica is widely cultivated as an ornamental tree. It is native to the southwestern United States but the seeds are sown in different countries such as Iran. In the present study, the ability of the rounded cones of Cupressus arizonica in adsorption and elimination of the acidic red color from the aqueous solution has been investigated. For preparing absorbent, rounded cones were picked up and ground properly. Then the powder was boiled in deionized water for 3 times and then immersed in acidic solution in order to be eliminated from some contaminants. In the next step, it was immersed in deionized water for several times until the solution pH became neutral. Finally, it was dried in an oven in 95°C for 24 hours. After all, the powder was ready to be used in wastewater treatment process. To optimize the treatment efficiency, different parameters like the amount of adsorbent, the concentration of dye solution, pH and adsorption time were studied. The results showed that, as the amount of adsorbent and adsorption time increases, the removal efficiency is enhanced. Furthermore, the obtained data revealed that, as the pH and concentration of dye solution decreases, the elimination efficiency of color from the aquatic solution is increased. As a conclusion, the outcome of the wastewater treatment experiments in the optimum conditions demonstrated that the adsorbent can eliminate the pollutant up to 99% from the contaminated water.