Synthesis of zeolite from industrial wastes: a review on characterization and heavy metal and dye removal.

Increasing world population, urbanization, and industrialization have led to an increase in demand in production and consumption, resulting in an increase in industrial solid wastes and pollutant levels in water. These two main consequences have become global problems. The high Si and Al content of solid wastes suggests that they can be used as raw materials for the synthesis of zeolites. In this context, when the literature studies conducted to obtain synthetic zeolites are evaluated, it is seen that hydrothermal synthesis method is generally used. In order to improve the performance of the hydrothermal synthesis method in terms of energy cost, synthesis time, and even product quality, additional methods such as alkaline fusion, ultrasonic effect, and microwave support have been developed. The zeolites synthesized by different techniques exhibit superior properties such as high surface area and well-defined pore sizes, thermal stability, high cation exchange capacity, high regeneration ability, and catalytic activity. Due to these specific properties, zeolites are recognized as one of the most effective methods for the removal of pollutants. The toxic properties of heavy metals and dyes in water and their carcinogenic effects in long-term exposure pose a serious risk to living organisms. Therefore, they should be treated at specified levels before discharge to the environment. In this review study, processes including different methods developed for the production of zeolites from industrial solid wastes were evaluated. Studies using synthetic zeolites for the removal of high levels of health and environmental risks such as heavy metals and dyes are reviewed. In addition, EPMA, SEM, EDX, FTIR, BET, AFM, and 29Si and 27Al NMR techniques, which are characterization methods of synthetic zeolites, are presented and the cation exchange capacity, thermodynamics of adsorption, effect of temperature, and pH are investigated. It is expected that energy consumption can be reduced by large-scale applications of alternative techniques developed for zeolite synthesis and their introduction into the industry. It is envisaged that zeolites synthesized by utilizing wastes will be effective in obtaining a green technology. The use of synthesized zeolites in a wide variety of applications, especially in environmental problems, holds great promise.

Tetracycline (TC) removal from wastewater with activated carbon (AC) obtained from waste grape marc: activated carbon characterization and adsorption mechanism.

In this study, activated carbons were obtained from grape marc for tetracycline removal from wastewater. Activated carbons were obtained by subjecting them to pyrolysis at 300, 500, and 700 °C, respectively, and the effect of pyrolysis temperature on activated carbons was investigated. The physicochemical and surface properties of the activated carbons were evaluated by SEM, FTIR, XRD, elemental analysis, N2 adsorption/desorption isothermal, thermal gravimetric (TG) and derivative thermogravimetric (DTG), and BET surface area analysis. When the BET surface areas were examined, it was found that 4.25 m2/g for activated carbon was produced at 300 °C, 44.23 m2/g for activated carbon obtained at 500 °C and 44.23 m2/g at 700 °C, which showed that the BET surface areas increased with increasing pyrolysis temperatures. The pore volumes of the synthesized activated carbons were 0.0037 cm3/g, 0.023 cm3/g, and 0.305 cm3/g for pyrolysis temperatures of 300, 500, and 700 °C, respectively, while the average pore size was found to be 8.02 nm, 9.45 nm, and 10.29 nm, respectively. A better adsorption capacity was observed due to the decrease in oxygen-rich functional groups with increasing pyrolysis temperature. It was observed that the activated carbon obtained from grape skins can easily treat hazardous wastewater containing tetracycline due to its high carbon content and surface functional groups. It was also shown that the activated carbon synthesized in this study has a higher pore volume despite its low surface area compared to the studies in the literature. Thanks to the high pore volume and surface active groups, a successful tetracycline removal was achieved.

Removal of food dyes using biological materials via adsorption: A review.

It is alarming that synthetic food dyes (FD) are widely used in various industries and that these facilities discharge their wastewater into the environment without treating it. FDs mixed into industrial wastewater pose a threat to the environment and human health. Therefore, removing FDs from wastewater is very important. This review explores the burgeoning field of FD removal from wastewater through adsorption using biological materials (BMs). By synthesizing a wealth of research findings, this comprehensive review elucidates the diverse array of BMs employed, ranging from algae and fungi to agricultural residues and microbial biomass. Furthermore, this review investigates challenges in practical applications, such as process optimization and scalability, offering insights into bridging the gap between laboratory successes and real-world implementations. Harnessing the remarkable adsorptive potential of BMs, this review presents a roadmap toward transformative solutions for FD removal, promising cleaner and safer production practices in the food and beverage industry.

Electrochemical Detection of Uric Acid Based on a Carbon Paste Electrode Modified with Ta2O5 Recovered from Ore by a Novel Method.

Except for well-known commercial production procedures, this study demonstrates that Ta2O5 particles can be produced. Through a series of steps, highly pure Ta2O5 particles (99.45%) were produced from the raw ore. We have electrochemically detected one of the important nitrogenous compounds present in urine, "uric acid", by a Ta2O5 particle-modified carbon paste electrode (Ta2O5-MCPE) using cyclic voltammetry. The prepared electrode has shown excellent current sensitivity at a pH of 6.0 phosphate-buffered solution. We have found that 4 mg Ta2O5-MCPE has recorded the highest current sensitivity of 75.75 µA. The oxidation peak current was varied with the uric acid concentration in the range from 1 to 5 mM at 4 mg Ta2O5-MCPE. We have calculated the electrode-active surface area for a bare carbon paste electrode and 4 mg Ta2O5-MCPE using the Randles-Sevcik equation, and the values were found to be 0.0202 and 0.0450 cm2, respectively. On the other hand, the calculated values of limit of detection and limit of quantification were reported as 0.5937 × 10-8 M and 1.9791 × 10-8 M, respectively, for the prepared 4 mg Ta2O5-MCPE. The interfere studies revealed that the variation in the electrochemical signal of uric acid in the presence of different metal ions was found to be less than ±5%.

Cleaner production of polyurethane (PU) foams through use of hydrodesulfurization (HDS) spent catalyst.

Due to the increased population in the urbanized areas, considerable attention is being paid on the development of energy-efficient buildings. In construction, the use of insulating foams has grabbed considerable attention in recent decades due to their porous structure that can reduce thermo-acoustic conductivity leading to higher energy efficiency. Nonetheless, the production of certain foams (e.g., polymer foams) is based on harmful chemical substances, such as isocyanate, as well as having difficulty being recycled. In this regard, this study adopted the use of hydrodesulfurization (HDS) spent catalyst, which is a byproduct of petroleum industry and is known to be a hazardous solid waste material, to produce a more environmentally friendly composite foam with lower thermal conductivity. In this sense, a series of material property tests, as well as thermal conductivity test, have been conducted. In addition, to further confirm the impact of HDS inclusion in the produced foams, energy cost savings and CO2 emission reduction based on their actual application in four different environments and four different fuel types for heating have been evaluated. The results are found to be highly promising and point to the great potential of utilizing HDS spent catalyst as a hazardous waste to enhance the efficiency of foams leading to CO2 emission and energy use reduction by up to 68.79 kg/m2 and 8.6 kWh/m2, respectively. Finally, this would reduce the heating cost, up to 0.69 $/m2 in an idealized building. In the end, suggestions for future studies in this area are also provided.

Use of sulfuric acid-carbonization materials from grape pulp for the removal of hexavalent chromium (Cr(VI)): mechanism and characterization.

This study investigated the reduction of hexavalent chromium (Cr(VI)) with sulfur dioxide (SO2) and adsorption of Cr(VI) onto dried grape pulp carbonized with sulfuric acid. Cr(VI) reduction capacities of SO2 were determined. The filtrate was titrated with NaOH solution after shaking and filtering the carbonized material to retain unreacted sulfuric acid (H2SO4). Simple washing recovered 25-38% of the experimental acid at low concentrations. The carbonized material was washed twice with distilled water and then dried at 105 °C and weighed. The carbonized material had a yield of 56.6% (grape pulp/sulfuric acid ratios of 1:2), and the lower the H2SO4 content, the better the yield, suggesting that the higher the acid content, the lower the Cr(VI) content per unit grape pulp. Cr(VI) reduction capacities were 219.5, 195.3, and 190.9 mg Cr(VI)/g-H2SO4 for the grape pulp/sulfuric acid ratios of 1:1, 1:2, and 1:3, respectively. Novelty statement: A carbonaceous material was obtained from grape pulp by carbonizing with concentrated sulfuric acid. The main objective of this study was to evaluate gas, liquid, and solid products or co-products obtained during carbonization process for hexavalent chromium treatment in aqueous solutions. In this context, (a) hexavalent chromium reduction capability of the gas evolved during carbonization was determined, (b) characterization of unreacted acid recovered by washing the carbonized product left after carbonization step was done, (c) carbonaceous adsorbent obtained was characterized and (d) hexavalent chromium adsorption characteristics of carbonaceous material obtained was determined.HIGHLIGHTSReduction and adsorption mechanisms of hexavalent chromium were investigated.A waste recycling method was proposed.The effects of sulfuric acid on carbonization were assessed.The structures and chemical compositions of a carbonized material were evaluated.The carbonized material is a cost-effective porous adsorbent for a clean environment.

Direct and facile synthesis of highly porous low cost carbon from potassium-rich wine stone and their application for high-performance removal.

Alkaline potassium compounds such as K2CO3 and KOH are chemical activators used to produce activated carbons (ACs). The substance, known as wine stone or cream of tartar and formed in wine fermentation tanks during wine production from grape juice concentrates, consists of potassium hydrogen tartrate (KHC4H4O6). Highly porous carbons with various textural characteristics were obtained from organic wine stone subjected to simple heat-treatment. This procedure is a one-step carbonization treatment performed at different carbonization temperatures (400 and 900 °C) and times (15 and 360 min), and nitrogen flow rates (100 and 600 ml/min). The chemical and physical properties of AC were examined using SEM-EDX, FT-IR analysis, particle size distribution, iodine number, pHpzc, BET surface area, surface functional group analysis by the Boehm's titration. BET surface area, total pore volume, average pore diameter, iodine number, pHzpc and carbon content were 1814.6 m2 g-1, 0.7767 cm3 g-1, 18.2 Å, 1986.4 mg g-1, 6.18 and 92.96%, respectively. Pore size, surface area and pore volume increased with an increase in carbonization temperature, and AC surface had high porosity and acidic functional groups. A promising approach focusing on the use of potassium-enriched properties of wine stone for easy and environmentally friendly production of activated carbons is emphasized.

Adsorption of micronutrient metal ion onto struvite to prepare slow release multielement fertilizer: Copper(II) doped-struvite.

In this study, struvite (MgNH4PO4.6H2O) sample was prepared by precipitation. Synthetic struvite was used as an adsorbent to remove Cu(II) from aqueous solution. Struvite was characterized by X-ray diffraction, FTIR, particle size analysis, SEM-EDX, surface area and true density. Solubility of struvite in water and acid solutions was investigated. Batch adsorption experiments were carried out by changing the initial Cu(II) concentration, contact time, struvite dosage and temperature. Cu(II) adsorption was found to be highly pH-dependent, and maximum adsorption was observed in the basic pH range. Equilibrium data were applied to Langmuir, Freundlich and D-R adsorption isotherms. Kinetic data were also analyzed for pseudo-first, pseudo-second and intraparticle diffusion models. Langmuir adsorption isotherm and pseudo-second kinetic models fit best to the data. Maximum adsorption capacity was found to be 158.73 mg g-1 at 20 °C, pH of 6 and adsorbent dosage of 1 g L-1 for a contact time of 240 min. Activation energy, mean adsorption energy (from D-R isotherm) and thermodynamic parameters were evaluated, and the nature of adsorption was found to be physical, endothermic and spontaneous. On the basis of characterization upon struvite before and after adsorption, it was found that the electrostatic attraction supported the ion sorption on struvite surface, and the transformation of Cu(II) ion into copper phosphate and copper hydroxide occurred on struvite surface. After its adsorption, solubility study was carried out. Release of P, N, Mg and Cu into extracts was studied. Phosphorus, nitrogen, magnesium and copper solubility in pure water was lower than about 1%.

A study on cations and color removal from thin sugar juice by modified sugar beet pulp.

This article describes the use of citric acid modified sugar beet pulp as new ion-exchanger sorbent for the removal of metal cations and colorants from thin juice. The results of batch adsorption runs concerning the effects of contact time, material dosage, temperature and pH drop were presented and discussed. Experimental data on the removal of metal cations showed that the sorption process was rapid and reached equilibrium in 60 min. Modified material in acidic form caused to a significant pH drop in thin juice, which could result with sucrose inversion. Uptake of metal cations increased with temperature whereas that of color decreased. Neutralised type modified product gave more satisfying results. After six successive contacts, 49.7%, 37.5% and 43.7% removals for Ca-Mg, K and color, respectively, were obtained by using neutralised form of modified sugar beet pulp.

Heavy metals binding properties of esterified lemon.

Sorption of Cd(2+), Cr(3+), Cu(2+), Ni(2+), Pb(2+) and Zn(2+) onto a carboxyl groups-rich material prepared from lemon was investigated in batch systems. The results revealed that the sorption is highly pH dependent. Sorption kinetic data indicated that the equilibrium was achieved in the range of 30-240 min for different metal ions and sorption kinetics followed the pseudo-second-order model for all metals studied. Relative sorption rate of various metal cations was found to be in the general order of Ni(2+)>Cd(2+)>Cu(2+)>Pb(2+)>Zn(2+)>Cr(3+). The binding characteristics of the sorbent for heavy metal ions were analyzed under various conditions and isotherm data was accurately fitted to the Langmuir equation. The metal binding capacity order calculated from Langmuir isotherm was Pb(2+)>Cu(2+)>Ni(2+)>Cd(2+)>Zn(2+)>Cr(3+). The mean free energy of metal sorption process calculated from Dubinin-Radushkevich parameter and the Polanyi potential was found to be in the range of 8-11 kJ mol(-1) for the metals studied showing that the main mechanism governing the sorption process seems to be ion exchange. The basic thermodynamic parameters of metals ion sorption process were calculated by using the Langmuir constants obtained from equilibration study. The DeltaG degrees and DeltaH degrees values for metals ion sorption on the lemon sorbent showed the process to be spontaneous and exothermic in nature. Relatively low DeltaH degrees values revealed that physical adsorption significantly contributed to the mechanism.

Preparation of cation exchanger from lemon and sorption of divalent heavy metals.

A cation exchanging material was developed from lemon by modifying the pectic-cellulosic substances in the lemon peel by lemon juice having citric acid. For this purpose, chopped lemon removed from seeds and yellow skin was heated in two stages, firstly at 50 degrees C for 24h and subsequently at 120 degrees C for 2h. The material obtained was ground, repeatedly washed with water and dried. Lemon peel and lemon resin obtained were characterized through physicochemical analyses and FTIR spectroscopy. Heavy metal binding performance of this material was determined by removal tests conducted by using 10mM solutions of divalent metals. Experimental results show that the resin prepared from lemon is effective especially for Pb and Cu removals. For a lemon resin dosage of 10 g l(-1), sorption affinity of divalent metal ions is found to be in an order of Pb>Cu>Ni>Fe>Cd>Zn>Co>Mn. Typically, sorption capacities are about 0.87 and 0.43 mmol g(-1) for Pb and Mn, respectively.