Fixed-bed adsorption of pesticide agricultural waste using cross-linked adsorptive hydrogel composite beads.

Adsorption column blockage due to solid adsorbent material is prevalent in laboratory-scale applications. Creating composite materials with stable geometries offers a viable solution. By crafting hydrogel beads using sodium alginate (Alg) and a bio-source like activated carbon (RMCA-P), it becomes possible to effectively eliminate agricultural pollutants, including the pesticide 2,4-D, from aqueous solutions. To evaluate the performance of these beads, a range of structural and textural analyses such as DRX, FTIR, SEM/EDX, BET, Zeta potential, Boehm titration, and iodine number were employed. Moreover, the study found that optimizing certain parameters greatly enhanced adsorption column efficiency. Specifically, increasing the bed height while reducing the flow rate of the adsorbate and the initial concentration in the inlet proved beneficial. The column demonstrated peak performance at a flow rate of 0.5 mL/min, a bed height of 35 cm, and an inlet adsorbate concentration of 50 mg/L. Under these conditions, the highest recorded removal rate for 2,4-D was 95.49%, which was subsequently confirmed experimentally at 95.05%. Both the Thomas and Yoon-Nelson models exhibited a good fit with the breakthrough curves. After undergoing three cycles of reuse, the RMCA-P/Alg hydrogel composite maintained a 2,4-D removal percentage of 74.21%. Notably, the RMCA-P/Alg beads exhibited effective removal of 2,4-D from herbicidal field waters in a continuous operational mode.

Continuous treatment of highly concentrated tannery wastewater using novel porous composite beads: Central composite design optimization study.

This present study depicts the successful employment of fixed-bed column for total chromium removal from tannery wastewater in dynamic mode using sodium alginate-powdered marble beads (SA-Marble) as adsorbent. The SA-Marble composite beads prepared were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Brunauer, Emmett and Teller (BET) method. The adsorption process performance of this bio-sorbent was examined in batches and columns for real effluent (tannery wastewater). After 90 min, the total chromium removal efficiency could be kept above 90% in the batch experiment. The adsorption kinetics fit better with the pseudo-second-order model, indicating the chemisorption process and the adsorption capacity of about 67.74 mg g-1 at 293 K (C0 = 7100 mg L-1) was obtained. Additionally, dynamic experiments indicate that the total chromium removal efficiency could be maintained above 90% after 120 min at 293 K and 60 min at 318 and 333 K; it's an endothermic but rapid process. The effects of two adsorption variables (Temperature and time) were investigated using central composite design (CCD), which is a subset of response surface methodology (total Cr, COD, sulfate, and total phosphorus percentage removal). This work paves a new avenue for synthesizing SA-Marble composite beads and provides an adsorption efficiency of total chromium removal from tannery wastewater.

Phenolic compounds removal in table olive processing wastewater by column adsorption: conditions' optimization.

The annual production of wastewater from the olive table industry poses a serious problem owing to its high organic matter load, which is highly concentrated in phenolic compounds (PCs) and inorganic materials. This research used adsorption to recover PCs from table olive wastewater (TOWW). Activated carbon was employed as a novel adsorbent. The activated carbon was obtained from olive pomace (OP) and activated using a chemical agent (ZnCl2). Fourier transform infrared spectroscopy analysis (FTIR), Brunauer-Emmett-Teller analysis (BET), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were applied to characterize the activated carbon sample. To optimize the biosorption conditions of PCs (adsorbent dose (A), temperature (B), and time (C)), a central composite design (CCD) model was used. An adsorption capacity was 1952.34 mg g-1 for optimal conditions with an activated carbon dose of 0.569 g L-1, a temperature of 39 °C, and a contact time of 239 min. The pseudo-second-order and Langmuir models as kinetic and isothermal mathematical models were proved to be more appropriate for the interpretation of the adsorption phenomenon of PCs. PC recovery was performed in fixed-bed reactors. The results of the adsorption of PCs from TOWW by activated carbon could be an effective process at a low cost.

Optimization of preparation conditions of a novel low-cost natural bio-sorbent from olive pomace and column adsorption processes on the removal of phenolic compounds from olive oil mill wastewater.

Olive oil mill wastewater (OMWW) poses an undeniable environmental problem due to its high organic loads and phenolic compound (PC) content. This study determined the optimal conditions for preparing a new bio-sorbent from olive pomace (OP) and the adsorptive treatment of OMWW by this bio-sorbent. The activation reaction was performed with hydrogen peroxide. The results of the combination effect optimization of the three preparation variables, the activation temperature (°C) X1, the activation time (min) X2, and the impregnation ratio X3, are presented by the response surface methodology (RSM). The maximum adsorption capacity was obtained at an activation time of 240 min, a temperature of 80 °C, and a ratio equal to 6.2:1. The bio-sorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD). The adsorption process performance of this bio-sorbent was examined in batch (phenol solution) and fixed-bed columns (real effluent of OMWW). An adsorption capacity of 789.28 mg g-1 and 643.92 mg g-1 has been achieved for 4000 mg L-1 concentration of PCs, respectively, for batch and fixed-bed column essays. The adsorption isotherm and kinetics were consistent with the Langmuir and pseudo-second-order models. Therefore, the Thomas model best fits the fixed-bed column experimental data. The bio-sorbent gave a high desorption percentage of PCs, which was above 60% using HCl (0.1M).