Efficient removal of pharmaceutical contaminants from water and wastewater using immobilized laccase on activated carbon derived from pomegranate peels

In this study, pomegranate peels (PPs) as an abundant fruit processing waste was used to produce cost-effective, eco-friendly, and high-quality activated carbon. The produced carbon (fossil free activated carbon) was used for immobilizing laccase to remove a range of emerging pollutants namely diclofenac, amoxicillin, carbamazepine, and ciprofloxacin from water and wastewater. The loaded activated carbon by laccase (LMPPs) and the unloaded one (MPPs) were characterized using advanced surface chemistry analysis techniques. MPPs was found to have a porous structure with a large surface area and an abundance of acidic functional groups. Laccase immobilization reduced surface area but added active degradation sites. The optimal immobilization parameters were determined as pH 4, 35 °C, and a laccase concentration of 2.5 mg/mL resulting in a 69.8% immobilization yield. The adsorption of the emerging pollutant onto MPPs is best characterized as a spontaneous endothermic process that adheres to the Langmuir isotherm and first-order kinetics. Using synergistic adsorption and enzymatic degradation, the target pollutants (50 mg/L) were eliminated in 2 h. In both water types, LMPPs outperformed MPPs. This study shows that pomegranate peels can effectively be harnessed as an enzyme carrier and adsorbent for the removal of emerging pollutants even from a complex sample matrix. The removal of contaminants from wastewater lasted five cycles, whereas it continued up to six cycles for water.

Characteristics of Cu(II)-modified aerobic granular sludge biocarbon in removal of doxycycline hydroxide

In this study, the biocarbon derived from aerobic granular sludge with different nutritive proportions was modified by Cu(NO₃)₂•3H₂O (Cu-BC) to improve its adsorption capacity of doxycycline hydrochloride (DOX). The surface area, pores, functional groups, and element composition of biocarbon were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectrometer, X-ray diffraction (XRD), the X-ray photoelectron spectrometer, and Fourier transform infrared spectrometry (FT-IR), respectively. Effects of DOX concentration, initial pH, and background electrolyte on adsorption effects of composite were analyzed. Furthermore, the adsorption kinetics, isotherm, thermodynamics, and diffusion model were investigated. Results demonstrated that biocarbons which were prepared with aerobic granular sludge under different nutritive proportions presented different performances. The BET specific surface area of Cu-NaAC/AGS-BC was 260.1592 m²/g, and the micropore volume was 0.054101 cm³/g. The BET specific surface area of Cu-GLC /AGS-BC was only 10.6821 m²/g, and the micropore volume was 0.008687 cm³/g. Both kinds of modified biochar contain a large number of oxygen-containing functional groups. The highest adsorption efficiency of Cu-BC could reach 99.54%. The adsorption of DOX on two modified biocarbons conforms to the pseudo-second-order dynamic model and Temkin isothermal model.

Synthesis and performance evaluation of adsorbents derived from sewage sludge blended with waste coal for nitrate and methyl red removal

Low-cost adsorbents were synthesized using two types of sewage sludge: D, which was obtained during the dissolved air flotation stage, and S, which was a mixture of primary and secondary sludge from the digestion and dewatering stages. The sewage sludge was mixed with waste coal before being activated with potassium hydroxide (KOH) and oxidized with ammonium persulfate (APS). The nitrate and methyl red removal capacities of the synthesized adsorbents were evaluated and compared to those of industrial activated charcoal. The oxidation surface area of adsorbents derived from sludge S shrank by six fold after modification i.e., from 281.72 (unoxidized) to 46.573 m2/g for the oxidized adsorbent with a solution of 2M ammonium peroxydisulfate, while those derived from D only varied narrowly from 312.72 to 282.22 m2/g, but surface modification had no effect on inorganic composition in either case. The adsorption of nitrate and methyl red (MR) was performed in batch mode, and the removal processes followed the pseudo second order kinetic model and the Langmuir isotherm fairly well. The adsorption capacities of nitrate and MR were higher at pH = 2 and pH = 4, respectively.

Instructive analysis of engineered carbon materials for potential application in water and wastewater treatment

Water remediation is an essential component for sustainable development. Increasing population and rapid industrialization have contributed to the deterioration of water resources. In particular, effluents from chemical, pharmaceutical, petroleum industries, and anthropogenic activities have led to severe ecological degradation. Many of these detrimental pollutants are highly toxic even at low concentrations, acting as carcinogens and inflicting severe long-lasting effects on human health. This review underscores the potential applications of engineered carbon-based materials for effective wastewater treatment. It focuses on the performance as well as efficiency of activated carbon, graphene nanomaterial, and carbon nanotubes, both with and without chemical functionalization. Plausible mechanisms of action between the chemically functionalized adsorbent and pollutants are also discussed. Based on the keywords from the literature published in the recent five years, a statistical practicality-vs-applicability analysis of these three materials is also provided. The review will provide a deep understanding of the physical or chemical interactions of the wastewater pollutants with carbon materials.

The sludge-based adsorbent from oily sludge and sawdust: preparation and optimization

Sludge-based adsorbent (S-AB) converted by oily sludge can make full use of the precious resource. In this paper, oily sludge and discarded sawdust are used to prepare adsorbent through chemical activation. The adsorbent prepared is used to adsorb raw petroleum. Firstly, the most reasonable chemical activator ZnCl₂ is ascertained through parallel comparative experiments. The characterization results of N₂-adsorption are consistent with adsorption experiment results, which shows that higher mesopore surface area and volume are benefitted by the adsorption process. Secondly, the optimization of preparation technology is investigated through orthogonal experiments after parallel comparative experiments. The adsorption capacity of S-AB-ZnCl₂ is stronger when the preparation conditions are as follows: an activation temperature of 550°C, an activation time of 3.5 h, a solid-liquid ratio of 1:1.5, a sludge-sawdust ratio of 1:0.5 and the heating rate of 15°C/min. The maximum quantity adsorbed Q₀ = 434.78 mg/g, calculated through the Langmuir adsorption isothermal models, of S-AB-ZnCl₂ prepared under optimized condition is higher than that before optimization. In addition, the most reasonable kinetics fits were of the second-order model.

Highly Efficient Removal of Methylene Blue Dye from an Aqueous Solution Using Cellulose Acetate Nanofibrous Membranes Modified by Polydopamine

A new type of deacetylated cellulose acetate (DA)@polydopamine (PDA) composite nanofiber membrane was fabricated by electrospinning and surface modification. The membrane was applied as a highly efficient adsorbent for removing methylene blue (MB) from an aqueous solution. The morphology, surface chemistry, surface wettability, and effects of operating conditions on MB adsorption ability, as well as the equilibrium, kinetics, thermodynamics, and mechanism of adsorption, were systematically studied. The results demonstrated that a uniform PDA coating layer was successfully developed on the surface of DA nanofibers. The adsorption capacity of the DA@PDA nanofiber membrane reached up to 88.2 mg/g at a temperature of 25 °C and a pH of 6.5 after adsorption for 30 h, which is about 8.6 times higher than that of DA nanofibers. The experimental results showed that the adsorption behavior of DA@PDA composite nanofibers followed the Weber's intraparticle diffusion model, pseudo-second-order model, and Langmuir isothermal model. A thermodynamic analysis indicated that endothermic, spontaneous, and physisorption processes occurred. Based on the experimental results, the adsorption mechanism of DA@PDA composite nanofibers was also demonstrated.

ZnCl2 modified biochar derived from aerobic granular sludge for developed microporosity and enhanced adsorption to tetracycline

In this study, biochar derived from aerobic granular sludge was modified by ZnCl₂ (Zn-BC) to improve the adsorption performance of tetracycline (TC). The surface area, pores, and functional groups of Zn-BC were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) and the effects of initial pH, TC concentration, and temperature on TC adsorption performance were analyzed. At the same time, the adsorption kinetics, isotherms, thermodynamics and diffusion models were studied. The results showed that the BET surface area and micropore volume of Zn-BC were 852.41 m²·g^-1 and 0.086 cm³·g^-1, respectively. The maximum adsorption performance of TC was 93.44 mg·g^-1, and it was less influenced by pH. The adsorption of TC on Zn-BC agreed well with the pseudo-second-order model and the Langmuir isotherm. The thermodynamic parameters indicated that the adsorption process was a spontaneously endothermic reaction.

Synthesis of amino-functionalized magnetic aerobic granular sludge-biochar for Pb(II) removal: Adsorption performance and mechanism studies

In the present study, a novel amino-functionalized magnetic aerobic granular sludge-biochar (NH₂-M-AGS) was successfully fabricated through magnetization and functional modification and applied for Pb(II) sorption. The composite was characterized by using scanning electron microscopy (SEM), energy dispersive spectrum (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential analysis, vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). The effects of adsorbent dosage, pH value, contact time and initial metal concentration on the adsorption of Pb(II) were investigated by using batch equilibrium experiments. It was concluded that the pseudo-second-order model was better to describe adsorption kinetic of Pb(II) onto NH₂-M-AGS. The Langmuir model was more accorded with the experimental data, and the maximum adsorption capacity of Pb(II) was 127.0 mg/g. A possible adsorption mechanism could be mainly caused by surface complexation, electrostatic attraction and precipitation. In five adsorption-desorption cycles, the desorption efficiency of Pb(II) exhibited a slight decline and still reached at 88.14%. Furthermore, the good reproducibility indicated that NH₂-M-AGS could be used a desirable, economic and recyclable adsorbent in practical metal-contaminated wastewater treatment.

Enhanced Capture Ability of Sludge-Derived Mesoporous Biochar with a Template-like Method

Sewage sludge-derived mesoporous biochars (SS-MBCs) were prepared by using cationic polyacrylamide (PAM⁺) as a template agent through a template-like method under high temperature and employed for getting rid of methylene blue (MB) from water. Textural evolution, mesostructured morphology, thermodynamic properties, and surface chemical groups of SS-MBCs were analyzed. It showed that PAM⁺ not only played an important role in good nucleation that brought well-developed texture and novel pore size distribution to SS-MBCs but also improved the MB adsorption capacities of SS-MBCs by increasing the specific surface area and the content of oxygen functional groups, especially the lactone. Preparation factor analysis indicated that PAM⁺ concentration, dosage of additive sludge, and carbonization temperature had distinct effects on material structure and adsorption performance especially above the pyrolytic temperature of 800 °C. The adsorption kinetics and isotherms were analyzed in detail, and it revealed that the kinetics and equilibrium adsorptions of SS-MBCs could be well-described by the Langmuir isotherm model and pseudo-second-order kinetics, respectively. Remarkably, the SS-MBCs showed higher removal efficiency and adsorption capacity than commercial activated carbon and most reported sludge-based adsorbents.

Isotherms and kinetic study of ultrasound-assisted adsorption of malachite green and Pb2+ ions from aqueous samples by copper sulfide nanorods loaded on activated carbon: Experimental design optimization

Copper sulfide nanorods loaded on activated carbon (CuS-NRs-AC) was synthesized and used for simultaneous ultrasound-assisted adsorption of malachite green (MG) and Pb²⁺ ions from aqueous solution. Following characterization of CuS-NRs-AC were investigated by SEM, EDX, TEM and XRD, the effects of pH (2.0-10), amount of adsorbent (0.003-0.011g), MG concentration (5-25mgL^-1), Pb²⁺ concentration (3-15mgL^-1) and sonication time (1.5-7.5min) and their interactions on responses were investigated by central composite design (CCD) and response surface methodology. According to desirability function on the Design Expert optimum removal (99.4%±1.0 for MG and 68.3±1.8 for Pb²⁺ions) was obtained at pH 6.0, 0.009g CuS-NRs-AC, 6.0min mixing by sonication and 15 and 6mgL^-1 for MG and Pb²⁺ ions, respectively. High determination coefficient (R²>0.995), Pred-R²-value (>0.920) and Adju-R²-value (>0.985) all are good indication of best agreement between the experimental and design modelling. The adsorption kinetics follows the pseudo-second order model and adsorption isotherm follows the Langmuir model with maximum adsorption capacity of 145.98 and 47.892mgg^-1 for MG and Pb²⁺ ions, respectively. This adsorbent over short contact time is good choice for simultaneous removal of large content of both MG and Pb²⁺ ions from wastewater sample.

Investigation of the influence of Ni(ii) exposure on the simultaneous nitrification and denitrification of aerobic granules from an internal oxygen penetration perspective

Lab-scale Sequencing Batch Reactors (SBR) were adopted to study the effects of Ni(ii) exposure on the simultaneous nitrification and denitrification (SND) of the aerobic granular sludge under different concentrations of Ni(ii) (1.0, 5.0 and 10.0 mg L⁻¹).

Ultra-high Rhodamine B adsorption capacities from an aqueous solution by activated carbon derived from Phragmites australis doped with organic acid by phosphoric acid activation

This study shows that oxalic acid (OA) and succinic acid (SA) were employed to modify Phragmites australis (PA)-based activated carbons (ACs) during phosphoric acid activation to improve Rhodamine B (RhB) removal from aqueous solutions.

Selective adsorption and separation of organic dyes from aqueous solution on polydopamine microspheres

Polydopamine (PDA) microspheres, synthesized by a facile oxidation polymerization route, were evaluated as a potential adsorbent for selective adsorption and separation of organic dyes. The adsorption processes towards nine water-soluble dyes (anionic dyes: methyl orange (MO), eosin-Y (EY), eosin-B (EB), acid chrome blue K (ACBK), neutral dye: neutral red (NR), and cationic dyes: rhodamine B (RhB), malachite green (MG), methylene blue (MB), safranine T (ST)) were thoroughly investigated. The adsorption selectivity of organic dyes onto PDA microspheres was successfully applied for the separation of dyes mixtures. Various influential factors such as solution pH, temperature, and contact time were employed to ascertain the optimal condition for adsorption of representative organic dyes including MB, MG and NR. The pseudo-first-order and pseudo-second-order kinetics models were used to fit the adsorption kinetics process. Five isothermal adsorption models (Langmuir, Dubnin-Radushkevich, Temkin, Freundlich and Harkins-Jura) were used to investigate the adsorption thermodynamics properties. The results showed that the PDA microspheres owned good selective adsorption ability towards cationic dyes. The adsorption kinetics process conformed to the pseudo-second-order kinetics model and the Langmuir isotherm model was more appropriate for tracing the adsorption behavior than other isotherm models. Thus, we can conclude PDA microspheres may be a high-efficiency selective adsorbent towards some cationic dyes.

Phosphate functionalized activated carbon as an efficient metal-free electrocatalyst for the oxygen reduction reaction

Phosphate functionalized activated carbon as a metal-free electrocatalyst exhibits excellent electrocatalytic activity for the oxygen reduction reaction in an alkaline medium.