In lower-pH (more acidic) solutions, there is a high enough H+ concentration in the solution to cause the acid to remain in its protonated form.
ɪn lˈoʊɚpˈiː ˈeɪtʃ mˈoːɹ ɐsˈɪdɪk səlˈuːʃənz, ðɛɹ ɪz ɐ hˈaɪ ɪnˈʌf ˈeɪtʃ plˈʌs kˌɑːnsəntɹˈeɪʃən ɪnðə səlˈuːʃən tə kˈɔːz ðɪ ˈæsɪd tə ɹᵻmˈeɪn ɪn ɪts pɹˈoʊtənˌeɪɾᵻd fˈɔːɹm.