Removal of malachite green from wastewater using date seeds as natural adsorbent; isotherms, kinetics, Thermodynamic, and batch adsorption process design.

This research explores the feasibility of using date seeds (DS), an agricultural waste, for the adsorption of malachite green (MG) dye from synthesized wastewater. The characterization of the DS before and after adsorption was accomplished by FTIR, SEM, BET, and EDX measurements. Batch adsorption experiments were investigated for MG dye adsorption from aqueous solution onto the DS. The effect of different parameters such as solution pH, adsorbent dose, contact time, temperature, and the initial dye concentration were studied. The optimum pH, adsorbent dose, temperature, and contact time for the dye removal were found to be 5, 0.1 g, 25 °C, and 30 min, respectively. The equilibrium studies for the data with Langmuir, Freundlich, and Temkin isotherms showed that Freundlich isotherm is the best model to describe the adsorption of MG onto the DS particles which has a heterogeneous surface. It was found that the adsorption process follows a pseudo-second-order kinetic model which revealed that the intra-particle diffusion stage is the rate-controlling stage for the process. The thermodynamic parameters ΔG, ΔS, and ΔH suggest the possibility of chemisorption and physisorption simultaneously and indicate the exothermic and spontaneous characters of the adsorption of MG dye on DS with negative values of ΔH and ΔG.

This study used agriculture waste (date seeds) which is proved to be an environmentally friendly and low-cost adsorbent. The date seeds were shown to be a promising adsorbent, demonstrating high surface area and well-developed porosity. The prepared adsorbent will have a great impact on wastewater treatment technology and possible applications at a large scale. Thus, widespread and great progress in this area can be expected in the future.

Removal of some heavy metals by CKD leachate.

In this study, Cu(II), Ni(II), and Zn(II) ions were precipitated from synthetic aqueous solutions as hydroxides by using CKD leachate. Precipitation tests were carried out batch wise in agitated flasks with single-metal solutions (each solution contained 100 mg/l of one of the three metals), and a multi-metal solution that contained 50 mg/l of each of the three elements. The results showed that high removal efficiencies, approaching 100%, of these heavy metals were attained and the leachate of the solid waste CKD, therefore, can be used for removing heavy metals from aqueous solutions.