A review on adsorbents for treatment of water and wastewaters containing copper ions

Techno-economic estimation of electroplating wastewater treatment using zero-valent iron nanoparticles: batch optimization, continuous feed, and scaling up studies

Electroplating manufacturing processes release industrial effluents that comprise severe levels of heavy metals into the environment. This study investigated the utilization of nanoparticles of zero-valent iron (nZVI) for the treatment of electroplating wastewater industry containing multiple heavy metal ions. In batch experiments using Cu²⁺ as a single solute, the optimum operating condition was pH 7.3, nZVI dosage 1.6 g/L, time 36 min, temperature 30 °C, and agitation speed 180 rpm, achieving almost 100% Cu²⁺ removal efficiency. The adsorption mechanisms were illustrated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) spectrometer. Moreover, continuous-feed experiments were performed to treat real electroplating wastewater industry via adsorption and sedimentation processes. The system attained removal efficiencies of 91.3% total suspended solids (TSS), 68.3% chemical oxygen demand (COD), 94.2% nitrogen (N), 98.5% phosphorus (P), 66.7% Cr⁶⁺, 91.5% Pb²⁺, 83.3% Ag⁺, 80.8% Cu²⁺, 17.4% Ni²⁺, 47.1% Mn²⁺, 54.6% Zn²⁺, 94.7% Fe³⁺, 100.0% Al³⁺, and 42.1% Co²⁺. The removal mechanisms included reduction of Meⁿ⁺ to Me^(n-x)+/Me⁰ by the Fe⁰ core, adsorption to the oxide shell as Me(OH)_x and Me-Fe-OOH, oxidation of Meⁿ⁺ to Me^(n+z)+, specific surface bonding, and sequential steps of electron transfer and precipitation. The total cost, including amortized and operating expenses for scaling up the adsorption system, was 4.45$ per m³ of electroplating wastewater. Graphical abstract.

Amino-functionalized sewage sludge-derived biochar as sustainable efficient adsorbent for Cu(II) removal

Sludge biochar as promising low-cost adsorbent has increasingly gained interests, but its poor surface functionality severely undermines its adsorption capacity and selectivity. Here a facile amino functionalization strategy was first proposed to enhance the surface functionality of sewage sludge derived biochar (SSDB) via the combination of sol-gel process for mesoporous silica coating and silylation for highly selective removal of Cu(II). The prepared amino-functionalized SSDB showed excellent adsorption capacity of 74.51 mg/g at room temperature, increasing by nearly 118% with regard to the unfunctionalized SSDB, and prominent selectivity (minute separation factor SF_{Co, Ni, Zn/Cu}) toward Cu(II) uptake. Characterizations demonstrated amine groups on the SSDB, the surface density of which reached 1.34 mg/m². The adsorption kinetics of Cu(II) on amino-functionalized SSDB was well described by a pseudo-second order kinetic model while the adsorption isotherm data was well fitted by Sips model. The pH range in which the adsorption preferentially occurred was 3-5. The occurrence of amine group protonation undermined adsorption performance at a pH < 3. These effects of amino-functionalized SSDB toward Cu(II) uptake were a result of the grafted amine groups specifically complexing with Cu(II) in the tetrahedron. Hence, prominent adsorption performance and low-cost feedstock make amino-functionalized SSDB a sustainable adsorbent for Cu(II) removal in water resulting in a cleaner utilization of sewage sludge.

Environmental and social responsibility of companies cross EU countries - Panel data analysis

In recent years, the socio-environmental dimension has become a structural and strategic element of successful companies, where it is usually addressed through the concept of Corporate Social Responsibility. The challenge for business is to draft new paradigms for operational procedures and improve the business conditions towards social and environmental responsibilities. Companies focus on eco-innovations and the production of "green products". Green innovations or technologies can be used by firms of all sizes and organizations have various motives for implementing an environmental friendly strategy or processes. Conversely, consumers tend to move more towards green products, which provide them with a sense that they are protecting the environment. According to the data from the group of International Standards Organization ISO 14000 more organizations from the EU have registered their systems as "eco-friendly" over the last few years. Data in this study was obtained from company-level surveys across EU member states conducted by the World Economic Forum following the thematic research on Global Competitiveness Index. The static panel data regression model was employed to show that there is a strong relationship between innovation and "going green". The results from several models reveal that innovation is significant and positively associated with "going green". Access to green environment increases innovation among competitors to present products that are environmentally friendly. Also, we have found that corporate ethics influence firms to apply environment-friendly business practices.