Cr (VI) enters water resources via wastewaters of pigment, tanning, and plating industries. Cr (VI) in water is a dangerous pollutant and carcinogenic. In this work, turnip peel bioadsorbent was used to remove Cr (VI) from water. The SEM images showed porous structure of turnip peel. The specific surface area of turnip peel was measured 4.436 m2/g. The effects of the operating conditions including Cr (VI) solution initial concentration (5 to 20 mg/L) and pH (2 to 10), bioadsorbent dose (10 to 30 g/L), time (0 to 150 min), and temperature (25 to 85°C) were investigated. Adsorption isotherm corresponded to Langmuir model and maximum adsorption capacity was 14.45 mg/g at pH of 5. Cr (VI) removal of 78.36% was obtained in the operating conditions of initial Cr (VI) concentration of 10 mg/L, pH of 5, time of 60 min, and temperature of 25°C. Complete removal of Cr (VI) was reached with increase of temperature (to 85°C) or decrease of pH (to pH of 2). The main advantages of turnip peel bioadsorbent are the low cost, large adsorption capacity, and short time to reach equilibrium and shows the ability of bioadsorbents which usually are from agricultural wastes to remove Cr (VI) from water.

Removing metal pollutants from water sources has become a critical environmental concern, demanding ongoing research and innovation in remediation technologies. Among the treatment methods, adsorption, using organic materials derived from agro-industrial wastes, stands out. The use of bioadsorbents derived from agro-industrial wastes, such as aloe vera, can be an effective and environmentally friendly solution for removing aluminum or other pollutants in irrigation water. This study aims to evaluate the aluminum removal capacity of a bioadsorbent developed from aloe vera processing wastes, using an adsorption column at a laboratory scale. For this purpose, tests were carried out with different doses of bioadsorbent and at different influent pH, using a two-factor, three-level factorial design. FT-IR, RAMAN and SEM analyses were performed to characterize the adsorption mechanism between aluminum and the bioadsorbent, which is quite complex. The present study demonstrated that the developed bioadsorbent has an adsorption capacity between 1.14-0.64 mg/g and achieved aluminum removal rates above 73% in all experiments, with the maximum removal (about 98%) observed at pH 4.5. This high efficiency in aluminum removal, combined with the use of agro-industrial waste as a bioadsorbent source, makes it a cost-effective and environmentally friendly solution. This suggests a promising potential for real-world water treatment applications, particularly in irrigation systems. Such an approach offers a sustainable and efficient solution for contaminant removal, in line with the increasing focus on environmental responsibility in water management.

Removal of the basic fuchsin dye from the fabric manufacturing wastewater was studied using the batch method. The adsorbent was the rice husk, which is an inexpensive agricultural residue. Effects of pH, temperature, solution volume and duration of the reactions in the dye removal were investigated. The adsorbent, which was treated with a 3M sulphuric acid for 60 minutes, gave the best results. The best fitted isotherm of the process resembled that of Longmuir. The maximum adsorbent efficiency was 100 mg of fuchsin per 1 g of the acid- treated rice husk.

In this paper removal of methylene blue dye from wastewater was studied. Separation was studied by adsorption batch method. Adsorbent is tassel that is an agricultural waste. The effect of temperature, time, pH and solution volume on adsorption was investigated. This adsorbent was eluted and treated by Ethylenediamine 1M for 60 min. The best fitted isotherm model was Langmuir and maximum capacity was obtained 166 mg dye on 1g adsorbent. The best kinetic model was pseudo second order model.