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The application of sustainable materials for wastewater treatment can provide a better water quality, by eliminating toxic metals and also organic contaminants. In this study, we demonstrate a simple method to synthesize chitosan/diatomaceous earth composed (CSDE) as an adsorbent for simultaneous adsorption of Amido Black 10B (AB10B), Cd(II), and Cu(II) ions from aqueous solution. The synthesis is based on a surface physical modification of diatomaceous earth by chitosan as a binder. The effects of adsorbent dosage, initial ions concentration, contact time, and pH on the AB10B, Cd(II), and Cu(II) adsorption rate were investigated. Fourier transform infrared spectroscopy confirmed the successful preparation of the CSDE. Under optimal conditions, the adsorption isotherm of AB10B, Cd(II), and Cu(II) onto CSDE fitted the Langmuir model and the adsorption kinetics was well-correlated with the pseudo-second-order model. The CSDE composite exhibited excellent adsorption capacity toward AB10B, Cd(II), and Cu(II) in both single and multicomponent system with removal capacity of 132.8 mg/g—single; 115.3 mg/g—multicomponent (pH 2), 108 mg/g—single; 96.9 mg/g—multicomponent (pH 7), and 97 mg/g—single; 88.27 mg/g—multicomponent (pH 7), respectively, suggesting selective binding capacity and high adsorption efficiency of CSDE composite. The prepared adsorbent could be reused at least ten consecutive adsorption–desorption cycles with marginal decrease in the total adsorption capacity of both metals and AB10B. The prepared adsorbents showed a significant potential for AB10B, Cd(II), and Cu(II) ions recovery in industrial applications.

A novel adsorbent for an effective removing of Pb(II) and Ni(II) from aqueous systems in both noncompetitive and competitive modes was prepared by dispersion chitosan onto the diatomaceous earth (CSDE), and then was synthesized into a spherical shape by using a drop-wise method. Its chemical composition, microstructure morphology, and metal-binding mechanism were characterized by dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) techniques. Batch adsorption studies were utilized to evaluate the potential suitability of the prepared CSDE beads and to examine the impact of major adsorption parameters such as solution-pH, initial metal concentration, and contact time on the Pb(II) and Ni(II) adsorption. Under optimal conditions, the maximal adsorption capacities of the CSDE beads based on the Langmuir isotherm model were 175.22 mg/g for Pb(II) and 149.64 mg/g for Ni(II) for noncompetitive adsorption and 234.8 mg/g for both metals in competitive adsorption. The common foreign ions such as Na+, Mg2+, and Ca2+ had insignificant effect on the Pb(II) adsorption while Mg2+ and Ca2+ affected on Ni(II) adsorption. Adsorption kinetics of both metals followed a pseudo-second-order model better than pseudo-first-order model. The prepared CSDE beads could be reused at least ten consecutive adsorption-desorption cycles with marginal decrease in the total adsorption capacity of both metals.

Reverse osmosis is a major process that produces soft water from saline water, and its output represents the majority of the overall desalination plants production. Developing efficient membranes for this process is the aim of many research groups and companies. In this work, we studied the effect of adding cellulose micro crystals (CMCs) and cellulose nano crystals (CNCs) to the support layer and thin film nanocomposite (TFN) membrane on the desalination performance. SEM, TEM, ATR-FTIR, and contact angle measurements were used to characterize the membrane&rsquo, s properties, and membrane&rsquo, s performance were evaluated by water flux and NaCl rejection. Filling 2% of CNCs gel in the support layer improved the water flux by +40%, while salt rejection maintained almost the same, around 95%. However, no remarkable improvement was gained by adding CNCs gel to m-phenylenediamine (MPD) solution, which was used in TFN membrane preparation. Filling CMCs powder in TFN membrane led to a slight improvement in terms of water flux.

In this work, chitosan coated diatomaceous earth (CCDE) beads were synthesized by a drop-wise method and characterized by FTIR, BET, SEM, EDS, and zeta potential for Zn(II) ion removal from aqueous solution in batch and continuous processes. Several parameters have been studied such as solution-pH, initial Zn(II) ion concentration, temperature, flow rate, and contact time to investigate the Zn(II) ion uptake. The maximum adsorption capacity of Zn(II) ion onto CCDE beads was 127.4mg/g in batch studies. The adsorption followed Pseudo second order and was well fitted to Langmuir model, indicating monolayer adsorption behavior. The continuous adsorption studies showed decreasing breakthrough and exhausted time with increasing flow rate of solution. The breakthrough points were 220 and 115min at flow rate 3 and 6mL/min, respectively. Loaded CCDE beads with Zn(II) ions were successfully regenerated by 0.2M NaOH without damaging the adsorbents and up to 87% recovery in the fourth cycle. Anions in the solution had an insignificant effect on Zn(II) ion uptake by CCDE beads. Overall results suggested that the prepared adsorbents could be employed as a low-cost, sustainable, and excellent alternative material for Zn(II) ion removal from wastewater.

In order to obtain a sufficient removal of heavy metal ions from water, new resources should be exploited to design more efficient and eco-friendly adsorbents. In this work, we have demonstrated an efficient, simple, and reusable adsorbent, which can be operated at the water treatment site. The simultaneous adsorption behavior and competitive interactions between As(III) and As(V) from aqueous solution onto chitosan/diatomaceous earth composite (CSD) were investigated at different solution-pH and adsorbent dosages. The adsorption mechanism was interpreted depending on the data of X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy. Results of batch equilibrium experiments indicated that the pH and adsorbent dosages have significantly influenced the adsorption process, and the adsorption of heavy metals was better fitted with Langmuir isotherm and pseudo-second-order models. The binary maximal adsorption capacities of As(III) and As(V), as determined from the Langmuir adsorption isotherms, were 87.81 mg/g and 44.07 mg/g at a pH of 6, respectively. The presence of phosphate (PO43−) as co-existing anions has an obvious impact on the adsorption of arsenic species. Based on the obtained results, the prepared adsorbent showed a great promise to be used in arsenic species adsorption from aqueous solution.