Petai (Parkia speciosa) pod as adsorbent for removal of malachite green dye

Vegetable and fruit wastes produced in huge amounts from agricultural and food industries normally become the problem for municipal landfills because they are highly biodegradable. These waste that are disposed by incineration and landfilling are unsightly, unhygienic and are hazardous to the environment. Adsorption using agricultural waste is evolving to be more economical and are widely used as an alternative to replace many other method of dye removal. The use of adsorption technique is preferable in waste water treatment since they are cost effective and environmentally friendly. Lately, the discharge of dye effluents into water systems have become a major environmental issue. Some of these dye discharge is carcinogenic and toxic to both humans and aquatic organisms. The aim of this study is to investigate the potential of utilising petai (Parkia speciosa) pod waste as an adsorbent for removal of Malachite Green dye. Various parameters were studied such as, adsorbent size (0.125, 0.300 and 0.710 mm), adsorbent dosage (0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 gram), initial dye concentration (20, 50, 100, 200, 300 and 400 mg/L), contact time (0.01, 0.02, 0.05, 0.10, 0.50, 1, 4, 8,12, 16, 20 and 24 hours) and pH (3, 4, 5, 6, 7, 8, 9 and 10). From the study conducted, it was observed that a percentage of removal of 99.74% can be achieved under optimum conditions (adsorbent size:0.125 mm, adsorbent dosage: 0.3 g, initial dye concentration: 100 mg/L, contact time: 30 minutes, and pH: 6). The equilibrium data was studied using Langmuir and Freundlich isotherms to reveal the degree of adsorption favourability. The best fitted model was obtained using Langmuir model with a maximum adsorption capacity of 26.81 mg/g. Thus, these results conclude that petai pod have the potential to be utilised as a low-cost adsorbent for the removal of Malachite green dye.