Jarosites are residues generated during the purification of zinc and are composed mainly of iron sulfates ((Na, K)Fe₃(SO₄)₂(OH)₆). Due to the large volume of jarosite generated during the process, these residues tend to be deposited in large land areas and are not used. In the present work, jarosite was used without heat treatment (JST) as an adsorbent of hexavalent chromium contained in a sample of wastewater from a chrome plating industry under the following conditions: C₀ = 200 mg/L of Cr, T = 25 °C, and pH = 3. It was only possible to remove 34% of Cr (VI). Subsequently, a thermal treatment of a jarosite sample (JTT) was carried out at 600 °C. The heat-treated sample was later used as an adsorbent in the same conditions as those for JST. The maximum chromium removal was 53%, and the adsorption capacity was 10.99 mg/g. The experimental data were fitted to the Langmuir model and to the pseudo-second-order kinetic model. It was determined that the adsorption process involved electrostatic attractions between the surface of the positively charged adsorbent and the chromium anions contained in industrial wastewater.

Exponential population growth resulted in exponential demands for metals, especially for production of electronic devices, which are mainly sent to landfills at the end of their functional life. This practice poses a significant environmental hazard due to the presence of metals within these discarded materials, termed electronic waste or e-waste, which necessitate appropriate management strategies to avert adverse effects on both the ecosystem and human health. E-waste contains valuable metals often in concentrations rendering their recovery economically viable. Furthermore, the escalating demand for metals, driven by technological progress, has made the recycling of e-waste a crucial element of sustainable resource management. This work provides an overview of hydrometallurgical processing techniques for the recovery of valuable metals from the waste from electrical and electronic equipment, where hydrometallurgy plays a determinant role in the recovery of valuable metals such as copper, gold, and silver. These methodologies employ aqueous chemistry to facilitate the metal extraction, presenting a cost-effective and environmentally sustainable alternative when compared to production of metals by conventional mining practices. However, the economic viability of these alternative processes may fluctuate based on the specific type and concentration of metals present within the waste.

Cobalt has emerged as a strategic critical metal due to its essential role in rechargeable batteries, high-performance alloys, catalysts, and clean energy technologies. However, its supply chain remains heavily dependent on cobalt produced as a by-product of copper and nickel mining and is geographically concentrated, particularly in the Democratic Republic of Congo. This review provides a comprehensive assessment of cobalt geology, mineralogy, global reserves, market trends, primary extraction routes, and emerging secondary recovery strategies. Unlike previous reviews that address these topics separately, this work integrates geological occurrence, mineralogical characteristics, extraction technologies, and resource circularity within a unified framework aimed at evaluating future cobalt supply resilience. The main cobalt-bearing deposit types of sediment-hosted Cu–Co deposits, Ni–Co laterites, and magmatic Ni–Cu–Co sulphide deposits are compared in terms of their mineralogical characteristics and processing requirements. Hydrometallurgy is identified as the dominant industrial route, typically combining high-pressure acid leaching (HPAL) with downstream purification and recovery processes such as solvent extraction and electrowinning (SX–EW). Emphasis is placed on the relationship between ore mineralogy and process selection, as well as on the growing integration of secondary resources, including tailings, slags, and spent batteries, into existing cobalt production chains. Despite promising recovery rates at laboratory scale, challenges remain in impurity control, economic scalability, and integration into established refining infrastructure. This review demonstrates that secondary resources are evolving from supplementary feedstocks to strategically important contributors to cobalt supply. Future supply security will depend on feedstock diversification, more flexible refining systems, improved impurity management, and the implementation of sustainable circular-economy strategies.

Currently, with the rapid growth of the population, the demand for metals has increased, especially for the manufacture of electronic devices such as cell phones, computer equipment, among others. Once these devices stop working, most are sent to landfills, which represents a danger since these wastes contain metals and other materials that must be properly managed to prevent them from having a negative effect on the environment and the human being. On the other hand, e-waste contains valuable metals such as copper, gold, and silver, the concentration of which in these materials makes it cost-effective to recover. This paper presents a review of the extraction and recovery of valuable metals from electronic waste by hydrometallurgical methods, as well as patents and industrial processes related to the management and treatment of this waste.

At present, the toxic effect of synthetic insecticides influences great importance in the development of organic alternatives derived from natural oils. Fig oil (castor) is one of the most important products worldwide, due to the many applications that include uses in medicine, cosmetics, inks, soaps, disinfectants, lubricants, varnishes and enamels. The fig tree is historically native to Africa, however it is common in Latin American countries because it is said that I arrive to this continent from the conquest, it is currently in abundance in the state of Coahuila. It has been shown that fig oil contains compounds with insecticidal activity. Therefore, the toxicity of fig oil (Ricinus communis) was evaluated based on the NOM-098-SEMARNAT-2002 standard, Environmental protection-waste incineration, operation specifications and pollutant emission limits.