Application of adsorption process for phenolic compounds removal from aqueous environments: A systematic review

Wastewater from various types of industries such as synthetic resins, plywood industries, paper and pulp, gas and coke oven plants, paints, coal gas, tanning, textile, plastic, rubber, pharmaceutical, petroleum and mine discharges, contain different types of phenols. Phenolic compounds are toxic substances and some are known or suspected carcinogens. Therefore it is important to remove phenol and phenolic compounds from contaminated industrial aqueous streams before discharged into any water bodies. Adsorption of phenol and its derivatives from aqueous solution by activated carbon is one of the most investigated of all liquid phase applications of carbon adsorbents. Several adsorbents have been used for treatment of wastewater and removal of phenolic compounds. Literature contains various adsorption processes and adsorbents such as pistachio nut shell ash, Moringa peregrina tree shell ash, agricultural fibers, red mud, low cost clay, olive mill waste, natural zeolites, rubber seed coat, peat, fly ash, bentonite and … which have been used for the removal of phenol and its derivatives. Any of chemical, biological and physical treatment processes has its own advantages and disadvantages. It is worth mentioning that economic aspects of these processes are important, for example biosorption were found to be effective methods with scope for further research in this field in terms of cost effectiveness and regeneration. At present study various adsorbents used by the authors of this article and other researchers for phenol and its derivatives from aqueous environments have been reported and summarized. Additionally, more research is needed to find the practical utility of low-cost adsorbents on commercial scale.