Jurnal Rekayasa Kimia dan Lingkungan Volume 16, Number 2, Page 52 - 67, 2021 ISSN 1412-5064, e-ISSN 2356-1661 https://10.23955/rkl.v16i2.20739 52 Recent Development and Application of TiO 2 Nanotubes Photocatalytic Activity for Degradation Synthetic Dyes – A Review Euis Uswatun Hasanah 1 , Indar Kustiningsih 1,2* , Slamet 3 , Maughal Ahmed Ali Baig 4 1 Master’s Program in Chemical Engineering, Postgraduate Program, Universitas Sultan Ageng Tirtayasa, Cilegon, Banten, Indonesia 2 Department of Chemical Engineering, Faculty of Engineering, Universitas Sultan Ageng Tirtayasa, Cilegon, Indonesia 3 Department of Chemical Engineering, Faculty of Engineering, Universitas Indonesia, Depok, Jawa Barat 4 Department of Mechanical, CMR Technical Campus Kandlakoya, Medchal Road, Hyderabad 501401, India *E-mail: indar.kustiningsih@untirta.ac.id Article History Received: 16 April 2021; Received in Revision: 12 Agustus 2021; Accepted: 19 September 2021 Abstract Synthetic dyes waste from textile industries, produce of the problematic pollutants in wastewater. TiO2 based photocatalysis are materials that exhibit excellent absorption behavior for organic compounds in wastewater due it properties including nontoxicity, high photocatalysis degradation ability, and chemical stabilities. However, several challenges exist regarding TiO2 nanotubes pure applications for dyes degradation such as poor affinity, high band gap energy, and difficulty of recovery and easy to recombination so it would decrease effectiveness of the photocatalysis process. Therefore, more design and optimization testing need to be conducted on the treatment conditions in order to reach higher removal efficiencies with lower costs. The modified physical properties by adding metal dopant, nonmetal, and sensitizer significantly enhanced photocatalysis activity. These parameters, which affect photocatalysis activity on degrade dyes waste pollutants, are discussed in the current review. As a result, the photocatalysis becomes more expected, and encourages to further research development. Keywords: Degradation, dyes, Photocatalytic, synthetic, TiO2 1. Introduction Waste processing is a critical technology for both human life and the environment. Liquid waste is considered a problem, especially waste from the textile industry. The textile industry wastewater contains organic and inorganic materials with a high concentration in every process unit (Kustiningsih et al.,2020). Many textile industries use synthetic dyes because synthetic dyes have advantages such as being more economical, has many variations of colors, and being durable (Wildan et al., 2018). Organic compounds in water will reduce dissolved oxygen levels for aquatic organisms because this oxygen is used as an oxidizer for organic compounds (Widyo et al, 2018). Synthetic dyes are categorized as azo dyes. It has high toxicity, easily absorbed into the skin, and can be carcinogenic (Da et al., 2015). Various synthetic dyes are available, such as methyl orange, rhodamine B, remadzol red, and methylene blue. About 60%-70% of the dyes used in textile dyeing are synthetic dyes of the azo group (Bethi et al., 2016). Azo dyes are widely used in dyeing fabrics, especially for made of cellulose, rayon, and wool fibers. Azo dyes are difficult to degrade because it will be environmental pollution. And then, dye pollutants have a more serious environmental impact because it were contain mutagenic harmful chemicals and contained more metal components, such as Cu, Ni, Cr, High, and Co (Haryono et al., 2018). Various conventional wastewater treatment options are proposed, such as biological (Pavithra et al., 2019), chemical oxidation (Hartanto et al., 2019), adsorption methods (Thahir et al., 2019), and membrane filtration (Kiswanto.,2019). However, this method has some weaknesses, such as pollutants that are not always feasible and effective. Table 1 shows a list of weaknesses and strengths of different methods. The biological measures implemented by the bacterial strain are referred to as biodegradation methods (Sari et al., 2019).